Epidemiology Notecards Flashcards

Terms Definitions
Q: Define health.
-health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity (state of feeling weak, feeble)
-some authors emphasize the importance of the ability to adapt to environmental stressors and the ability to function in society as important dimensions of health
-health is a dynamic tension towards physical, mental, social and spiritual harmony and not only the absence of illness, which gives man the ability to fulfill the meission which has been entrusted to him, according to the state of life in which he finds himself
Q: What are the determinants of heatlh?
-social, economic, environmental, nutritional, behavioral, spiritual, cultural, physical, genetic, and infectious
-some say that appropriate nutrition, adequate shelter, a non-threatening environment and a prudent life contribute far more to health and well-being than does the medical care system
Q: What role does healthcare play in environment?
-healthcare services is a component of an individual’s or population’s living and working conditions and contributes to health through direct patient care and indirectly through development and dissemination of knowledge about disease prevention and treatment
Q: What is Maslow’s Hierarchy of needs?
-is a triangle of five stages that leads to personal growth and fulfillment
-the first stage (base of the triangle) is biological and physiological needs (basic life needs (air, food, drink, shelter, warmth, sex, sleep))
-the next stage is safety needs (protection, security, order, law, limits, stability
-belongingness and love needs (family, affection, relationships, work group)
-esteem needs (achievement, status, responsibility, reputation)
-self-actualisation (personal growth and fulfillment)
Q: Define public health.
-the health status of the public (of a defined population)
-the organized social efforts made to preserve and improve the health of a defined population
-what we as a society do collectively to assure the conditions in which people can be healthy
Q: What is the essence of public health?
-liberty is to the collective body what health is to every individual body, without health, no pleasure can be tasted by man, without liberty, no happiness can be enjoyed by society
Q: Give an operational definition of public health.
-The science and the art of preventing disease, prolonging life, and promoting physical health and efficiency through organized community efforts for the sanitation of the environment, the control of community infections, the education of the individual in principles of personal hygiene, the organization of medical and nursing services for the early diagnosis and preventive treatment of disease, and the development of the social machinery which will ensure to every individual in the community a standard of living adequate for the maintenance of health.
Q: What is the difference between clinical medicine and public health? How is it related to a forest?
-medicine is the trees while PH is the forest
-clinical medicine affects the individual while public health affects the population
-CM emphasizes curing, PH emphasizes prevention
-CM diagnose, treat, surgery, prescribe, give advice, PH assess, intervene, social and environmental change
-CM is science based with an emphasis on medical professionals, PH is also scienced based but is broad and multidisciplinary
-CM’s motto is do no harm, PH’s motto is common good (also prevent. promote. protect)
-CM decisions are paternalistic, PH decisions are political
Q: What are the 3 core functions of PH?
-assessment, policy development, and assurance
Q: Describe the assessment function of PH.
-requires that every public health agency regularly and systematically collect, assemble, analyze, and make available information on the health of the community, including statistics on health status, community health needs and epidemiologic and other studies of health problems
-they function to monitor pulse and vital statistics of the community, includes vital records, hospital data, special surveys, focus groups, surveillance, environmental data and community input
Q: What is the purpose of assessment in PH?
-collect data, analyze data, disseminate data, and manage data
Q: Describe the policy development function of PH.
-requires that every public health agency exercise its responsibility to serve the public interest in the development of comprehensive public health policies by promoting the use of the scientific knowledge base in decision-making about public health
-requires familiarity with the landscape and community, adapts to climate changes such as politics, norms, and economic forces
Q: What is the purpose of policy development?
-plan healthy communities, formulate, analyze and implement effective health policy, establish legal authority, assess impact of policy decisions
Q: Describe the assurance function of PH.
-requires that public health agencies assure their constituents that services necessary to achieve agreed upon goals are provided, either by encouraging action by other entitites (private or public sector), by requiring such action through regulation, or by providing services directly
-provides services not otherwise available or not reaching target population, requires decision making, advocacy, planning and regular review
Q: What is the purpose of assurance in PH?
-provision of services necessary to meet heatlh needs, encourage action, enforce regulations, provide services directly
Q: Describe the essential services of PH.
-they were defined by multi-agency workgroup of PH leaders in Fall 1994, clarified 10 services necessary to fulfill core functions of PH, help focus and guid objective of PH activities
Q: What are the 10 essential PH services and what core function of PH does it fit in?
-Assessment-(1) monitor health, (2) diagnose and investigate
-Policy development-(3) inform, educate and empower, (4) mobilize community partnerships, (5) develop politics
-assurance-(6) enforce laws, (7) link to/provide care, (8) assure competent workforce, (9)evaluate, (10) promote research
Q: Describe the essential PH services in the assessment core.
-Assessment-(1) monitor health status to identify and solve community health problems, (2) diagnose and investigate health problems and health hazards in the community
Q: Describe the essential PH services in the policy development core.
-Policy development-(3) inform, educate and empower people about health issues, (4) mobilize community partnerships and action to identify and solve health problems, (5) develop policies and plans that support individual and community health effors
Q: Describe the essential PH services in the assurance core.
-Assurance-(6) enforce laws and regulations that protect health and ensure safety, (7) link people to needed personal health services and assure the provision of care when otherwise unavailable, (8) assure a competent public health and personal health workforce, (9) evaluate effectiveness, accessibility and quality of personal health services, (10) promote research for new insights and solutions to health problems
Q: What are some public health assessment activites?
-Maintain air quality monitoring network
-Respond and resolve air quality complaints
-Conduct surveillance for communicable diseases to monitor disease burden
-Investigate health problems related to HIV, TB other communicable diseases
-Develop and identify data of chronic disease measures
-Collect data on births and deaths through vital statistics program
-Conduct surveillance of vector borne diseases and vector activity in pesticide applied areas
Q: What are some PH policy development activities?
-Support public information activities and campaigns
-Provide education to community and specialty groups (i.e. day care providers)
-Promote access to health care and prevention activities for groups at risk for health problems (i.e. kids, seniors)
-Provide information on communicable disease reporting requirements
-Support efforts to promote fluoridation of water or tobacco control measures
Q: What are some PH assurance activities?
-Issue ordinance violations and recommends penalties
-Train and certify staff in topical areas (workplace safety, asbestos, computer modeling, inspections and permitting)
-Provide workshops to industry on regulations
-Prepare summary reports on compliance with regulatory issues
-Provide oversight to and ensure compliance with agreements to provide emergency medical response services
-Provide immunizations as mandated
-Refer patients as needed to community providers when identified by clinical staff
-Link chronically ill persons to needed personal health care services
-Maintain link with community partners to promote prevention of chronic diseases
-Ensure fiscal responsibility of the health department to the community and public health partners
Q: Who delivers the essential PH services?
-public health agencies (federal, state, local), health care systems, community organizations, employers, educational institutions
Q: What is the level of authority of federal health?
-leadership -> support -> security
Q: Describe the structure of federal PH.
-there are 4 main administrations led by the secretary and support staff that make up the Department of Health and Human Services (DHHS), DHHS is the major federal department most concerned with health
-the 4 administrations are Administration on Aging (AoA), Administration for children and families (ACF), Center for Medicare/Medicaid services (CMS), and Public Health service (USPHS)
-USPHS is consisted of eight constituent agencies (AHRQ, CDC, ATSDR, FDA, HRSA, HIS, NIH, SAMSHA)
Q: What are the eight constituent agencies of USPHS?
-CDC (centers for disease control and prevention), NIH (National institutes of health), FDA (food and drug administration), IHS (Indian Health Services), SAMHSA (Substance abuse and mental health services administration), AHRQ (agency for healthcare research and quality), ATSDR (agency for toxic substance and disease registry), HRSA (health resources and services administration)
Q: What do the leadership positions take care of and what are its members?
-assesses health, passes legislation, regulates and disseminates recommendations
-include the CDC, NIOSH, SAMHSA, FDA
Q: What do the support positions take care of and what are its members?
-assists state and local public health authorities
-include EPA (for technical assistance and environmental cleanup), HRSA, NIH (for grants for programs and research), and HRSA, CMS (for health care services)
Q: What do the security positions take care of and what are its members?
-protects nation against threats, disease investigation, emergency health powers, quarantine, restriction of imports
-include USPHS
Q: What does the HRSA do?
-the nations agency for improving access to health care services for people who are uninsured, isolated or medically vulnerable
-administrations arm of federally-qualified community health centers (FQHCs)
-contains 6 bureaus and 12 offices
Q: What is the purpose of the state government in PH?
-Principal authorities responsible for PH
-10th Amendment grants power
-Have “police powers” to protect and promote health
-Oversee implementation of PH code
-Delegate authority to local PH authorities
-Oversee licensing to healthcare professionals and medical care institutions
Q: What is the hierarchy of the state PH?
-in each state, there is a state health department to oversee the implementation of the public health code, mental health can be the responsibility of the health department or there is a separate state department for it
-function to ensure health of the public by licensing medical and other health-related practitioners and medical care insititutions like hospitals, nursing homes and home care programs
Q: What is the motto of the Nevada Dept. of Health and Human Services?
-promotes the health and well-being of Nevadans and our visitors through the delivery and facilitation of essential services. Our goal is to strengthen families, protect public health, and assist individuals in achieving the highest level of self-sufficiency.
-Promotes and protects the health of all Nevadans and visitors to the state through its leadership in public health and enforcement of laws and regulations pertaining to public health.
Q: What are the different service division in the Nevada Dept. of Health and Human Services?
-Health (NV State Health Division), Aging, Child and Family, Mental Health and Developmental, Welfare and Supportive, Health Care Financing and Policy (Medicaid), Public Defender
Q: What are the divisions in the NV State health division?
-6 bureaus (community health, family health services, health protection services, early intervention services, health planning and statistics, licensure and certification
-4 offices (minority health, public information, epidemiology, PH preparedness)
Q: What is the purpose of the local section of PH?
-“Hands on” public health responsibility, Full range of PH core functions and essential service delivery, Vary by jurisdiction
Q: What are the Nevada County Health Districts?
-Southern Nevada Health District (Las Vegas and surrounding Clark County), Carson City Health and Human Services (Carson City only), Washoe County District Health Dept (Reno, Sparks, Washoe County), Remainder of state territories under supervision by NV State Health Division
Q: What is the purpose of the Washoe County District Health Dept?
-Protects and enhances the quality of life for all citizens of Washoe County through providing health promotion, disease prevention, public health emergency preparedness, and environmental services.
Q: What are the service divisions Washoe County District Healthy Dept?
-Administrative Health, Air Quality Mgmt, Community and Clinical Health Services, Environmental Health Services, Epi Center, PH Preparedness
Q: What are the state and local health department activities?
-Comprise many facets of public health, Often invisible to the community, Dynamic and fluid, Popular or unpopular, Subject to economic, technical, social and political forces
Q: What are some other partners in Public Health?
-Governmental-OSHA, USAID, DHS
-Non-governmental-APHA, NPHA, APTR, ACS, AAFP, AMA, AAP, business cooperatives on health, coalitions (eg. Nevada Health Care Coalition)
Q: What are the 10 great achievements in PH?
Immunization, Motor-vehicle safety, Safer workplaces, Control of infectious diseases, Decline in deaths from coronary heart disease and stroke, Safer and healthier foods, Healthier mothers and babies, Family planning, Fluoridation of drinking water, Recognition of tobacco use as a health hazard
Q: Define preventive medicine.
-a medical speciality emphasizing practices that help individuals and populations promote and preserve health and avoid injury and illness, it is a recognized speciality by ABMS
-specialists uniquely trained in clinical medicine and public health, have the skills needed to understand and reduce the risks of disease, disability and death in individuals and in population groups
Q: What are the similarities between PH and preventive medicine?
-they both promote general health, prevention of specific diseae and use epidemiology conceptrs and technique
Q: How do PH and PM differ?
-PM may take a more individualized focus but keep the community of the individual in mind, the concept of “Community-oriented Primary Care”
-PH promotes population health through organized community efforts, the concept of “Healthy People in Healthy Communities”
Q: What is the difference between PM and Curative medicine?
-traditional allopathic education (ie. where you are sitting right now) tends to focus on diagnosis and treatment (the cure!) but this is still considered preventive medicine
-preventive medicine focuses on preservation and enhancement of health and limitation of disability
-Dr. C’s recommendation: Regardless of your future specialty, consider yourself a preventive medicine practitioner
Q: What is the natural history of disease?
-start with pre-disease-individuals posses factors that resist or promote disease development (genetics, demographics, environment, nutrition, social, immunological capability, behavioral patterns)
-pre-disease can turn into a latent (hidden) stage-process underway but no clinical symptoms, this stage offers a window of opportunity for screening that may detect a disease allowing treatment and better chance for cure
-latent stage can enter a symptomatic (manifest) stage which produces clinical manifestations
Q: What is Leavell’s levels of prevention?
-three levels of preventive health care (primary, secondary, tertiary) based on the premise that all of the activites of physicians and other health professional have the goal of prevention
-what is to be prevented depends on the stage of health or disease in the individual receiving preventive care
Q: What are the different types of prevention and where do they attack?
-primary prevention attacks at pre-disease
-secondary prevention attacks at latent stage
-tertiary prevention attacks at symptomatic stage
Q: Describe primary prevention.
-Prevents disease process from being established by eliminating causes of disease or increasing resistance to disease
-Methods include Health Promotion and Specific Protection
Q: Describe Health promotion.
-generally nonmedical changes (lifestyle, behavioral, nutritional, environmental, societal)
-may require re-engineering or structural improvements to society (eg. creation of sewage systems or latrines to improve waste management and decrease exposure)
-societal changes must sometimes occur (eg. decrease neighborhood violence, allows increase in outdoor physical activity for kids)
Q: Describe specific protection.
-generally target a specific disease or type of injury (eg. primary example- immunizations, ear protection for airport tarmac workers to decrease high decibel auditory exposure and damage)
Q: Describe secondary prevention.
-interrupts the disease process before it becomes symptomatic, have window of opportunity (when detection and early treatment provides better chance of cure or more effective treatment)
-methods include screening (for populations) and case finding (for individuals in medical care)
Q: What are the criteria for screening?
-normally want to if it is serious disease, if a treatment is available, if a window of opportunity exists, and if it is not too rare or common
-screens should be quick, easy and inexpensive, they should be safe and acceptable to screeners and persons being screened, and the testing parameters are acceptable
Q: Describe tertiary prevention.
-limits the physical and social consequences of symptomatic disease, when disease becomes symptomatic, patients seek healthcare advice and treatment
-Methods include Disability limitation and Rehabilitation
Q: Describe disability limitation.
-Majority of care provided by physicians, Medical and surgical measures aimed to return the symptomatic patient back to, or as closely to, health such as penicillin for strep throat, weight reduction to eliminate hyperlipidemia, appendectomy for acute appendicitis, sudafed for nasal congestion, prosthetic knee replacement to relieve knee pain, narcotic pain medications to relieve cancer-related pain, IV fluids to reverse acute renal failure
-Prevention because meant to halt disease process and limit the impairment from the process
Q: Describe rehabilitation.
-Mitigates the effects of disease and prevents total social and functional disability, it strengthen pt’s remaining functions, help pts learn to function in alternative ways (ex: post-CVA patient re-trained in activities of daily living (ADLs), double amputee trained in wheelchair use)
Q: What percent of the US is obese?
-60 million adults (30% of the adult population) are now obese, which represent a doubling of the rate since 1980
Q: Describe the rising US health care costs.
-spending expected to INC from 2.3 trillion in 2007 to 4 trillion in 2015, annually per person we spend 8500
-It’s happened over the past 40 years – not overnight! More than any other industrialized nation – only one that does not provide health care to all its citizens and does not guarantee the delivery of preventive health measures such as immunizations and screening exams known to catch disease early or head off the chance of more advanced/costly disease. <$5 of every $100 spent on preventive care.
Q: Describe the INC in health insurance premiums that has occurred.
-annual INC in health insurance premiums have ranged from 6-13% since 2000, chronic diseases account for 75% of health care costs
-How are we paying for that big price tag? With increased premiums. Premiums for employer-sponsored health insurance rose an average 6.1 percent in 2007
Q: How many deaths per 100,000 in the US are from potentially preventable deaths? How does this compare to other countries?
-about 110 deaths are due to potentially preventable deaths
-US ranks last in potentially preventable deaths among 19 industrialized nations. In a Commonwealth Fund-supported study comparing preventable deaths in 19 industrialized countries, researchers found that the United States placed last. compared international rates of “amenable mortality”—that is, deaths from certain causes before age 75 that are potentially preventable with timely and effective health care. While the other nations improved dramatically between the two study periods—1997–98 and 2002–03—the U.S. improved only slightly on the measure. The concept of amenable mortality was developed in the 1970s to assess the quality and performance of health systems and to track changes over time.
-The rate of amenable mortality is a valuable indicator of health care performance, say the authors—one that can point to potential weaknesses in a nation’s health care system
-For this study, the researchers used data from the World Health Organization on deaths from conditions considered amenable to health care, such as treatable cancers, diabetes, and cardio-vascular disease.
Q: Does our health system deliver the recommended preventive services?
-health care system fails to deliver recommended preventive services, according to healthy people 2010 target, our numbers of pap screening, colorectal screening, mammogram, diabetic HbA1c screening, diabetic eye exam, BP test, and cholesterol test are all lower than the target
-despite highest Per Capita Expenditure on Health Care among industrialized nations, we fall short of providing the recommended screening/preventive measures that are well known to prevent disease, cancer or disability.
Q: What are the strategies to manage rising costs of health care?
-Raise deductibles, premium contributions, and co-pays (Employee contribution increased 143% since 2000 and Out-of-pocket costs rose 115%)
-Decrease or eliminate coverage (60% offer coverage
Q: What are the limitations of cost shifting?
-Decreased utilization of preventive services
-Delays in treatment result in complications
-Cases shift to workers compensation claims
-Meanwhile, employee recruitment, training and retention become an emerging concern…as does post-employment benefit liability
Q: What is driving the INC in health care costs?
-Medical innovation (Pharmaceuticals - Specialty/Biotech, New technology and specialized testing)
-Reimbursement and coverage (Increasing numbers of uninsured or under-insured, Cutbacks in Medicare/Medicaid reimbursement)
-System issues (Inefficiencies and fragmented care, Medical errors and quality)
-Practice challenges (Defensive medical practice, Preventive care not valued)
Q: Why is the cost of insurance for those with coverage increasing?
-The cost of insurance for those with coverage is escalating in part because the number of uninsured Americans keeps rising, Families USA determined that the unpaid expenses for the uninsured added an average $922 in 2005 to the premiums for employer-provided family health insurance. That extra cost could rise to $1,502 in 2010, the group found. Eighty percent of people who are uninsured are working and some at more than one job. Robert Wood Johnson Foundation. CT: According to the Office of Health Care Access (OHCA) 2004 Household Survey, an estimated 5.8 percent of the state’s population, or 196,200 Connecticut residents, are uninsured. The state’s uninsured rate has remained fairly stable
Q: What group of the population has the highest likelihood of uninsurance?
-Young adults had the highest likelihood of uninsurance: 16.8% are uninsured. Compared with all other age groups, young adults (age 19 to 29) are nearly four times as likely to be uninsured. 2/3 of these persons are working.
-Hispanics have the greatest likelihood of being uninsured: 21% uninsured. Hispanics are five and a half times more likely to be uninsured as persons from all other ethnic or racial groups.
-Nearly two-thirds of all working age uninsured adults are gainfully employed. Since 2001, the share of working uninsured has declined slightly (-2%).
Q: Why is there an INC in the cost of diabetes?
-the growth in diabetes prevalence
-medical costs rising faster than general inflation
-improvements made in the methods and data sources influencing cost estimates.
Q: What is the monetary burden of diabetes?
-The actual national burden of diabetes likely exceeds the $174 billion estimate because it omits the social cost of intangibles such as pain and suffering, care provided by non-paid caregivers, excess medical costs associated with undiagnosed diabetes, and diabetes-attributed costs for health care expenditures categories not studied. Highest per capita expenditure fails to improve health outcomes
Q: What effect does an aging population have on healthcare costs?
-Currently 1 out of 8 people in the US are over 65
Q: Describe the change in the US population by age gropu.
-Reflects the changing demographics of our population. Flow of persons transitioning from the work force into retirement. By 2025, smaller proportion of younger persons are entering the workforce. get DEC in people in the pre-working age group, INC in people over 65
Q: Describe the worsening health status of the population.
-With the successful control of most infectious diseases over the past 50-60 years, there has been an increasing awareness of the prominent role that chronic diseases play in the morbidity and mortality of citizens in our country. In fact, many people are calling it a chronic disease epidemic. In addition to heart disease, cancer, and stroke, which are the top three causes of death in the United States, the prevalence and incidence of obesity and diabetes steadily increased throughout the 1990s.
Q: Describe how the obesity numbers have changed from 1987 to 2007.
-in 1987, 15 states reported obesity rates from 10-14%, none greater than 14%
-in 2007, 28 states reported obesity rates from 25% to 29% and 3 states > 30%, CO stands alone (weighing in at 19.3% adults obese in 2007)
Q: How many Americans are obese in America?
-43% adults are overweight – up 40% in past 20 years, 31% adults meet criteria for obesity – doubled in 20 years, Among children – 17% kids 6 – 19 years obese – tripled in 30 years
-A 2002 study published in the Journal of the American Medical Association indicated that 9 million American children are overweight, three times the number from two decades earlier. The federal Centers for Disease Control and Prevention in Atlanta found that obesity among children ages 2 to 5 has increased 35 percent in 10 years.
Q: Describe the disparaties between ethnic groups and obesity.
-Mexican American and black (non-Hispanic) adults in the U.S. are considerably more overweight and obese than white (non-Hispanic) adults
-For men, the Mexican American population has the highest prevalence of overweight (74.4 percent) and obesity (29.4 percent).
-For women, the black (non-Hispanic) population has the highest prevalence of overweight (78 percent) and obesity (50.8 percent). – 2/3rds higher than gen’l pop
-American Indian population also has high prevalence rates of overweight/obese – 1/3rd higher than gen’l pop
Q: How has the proportion of obese adults changed in the past 25 years?
-Currently, 2/3 American adults are overweight or obese. The proportion of obese adults has doubled over the past 25 years – from 15% in 1980 to 30% in 2004. Obesity relates to increased rates of diabetes, heart disease, stroke, cancers and musculoskeletal problems – for every $100 in annual health care costs, 38% more on obese compared to non-obese. 1/3 of American Workforce is Obese!
-Increase prevalence in mid-age reflects loss of metabolic activity and decreased activity. However, in >65, proportion decreases – why? Reflects morbidity rate of those with obesity due to related conditions such as heart disease and diabetes.
Q: What are some obesity-related illnesses and diseases?
-Type II Diabetes, Stroke, Cardiovascular Disease (High Blood Pressure, High Cholesterol), Pulmonary Disease (Sleep Apnea, Respiratory Problems), Cancer, Acid Reflux Disease
-Psychological/Social Effects, Gallbladder Disease, Bladder Control Problems, Uric Acid Kidney Stones, Gout and osteoarthritis, Reproductive Issues, (Women–pregnancy complications, irregular menstrual cycles, Men–infertility), and Musculoskeletal problems
Q: Describe the relationship between cancer and obesity.
-Obesity appears to contribute to the higher risk of pancreatic cancer among black Americans than among whites, particularly for women.
Q: Describe the relationship between heart disease and obesity.
-Among African Americans, the high prevalence of obesity and obesity-related conditions such as hypertension and type 2 diabetes, are factors reported to contribute to their high death rate from coronary heart disease. In a study of older Hispanics, with an average age of 80, obesity was found to be a risk factor for developing coronary artery disease.
Q: Describe the relationship between hypertension and obesity.
-The high prevalence of obesity is reported to be a contributing factor to the high prevalence of hypertension in minority populations, especially among African Americans who have an earlier onset and run a more severe course of hypertension.
Q: Do cultural and behavioral factors affect obesity?
-Cultural factors related to dietary choices, physical activity, and acceptance of excess weight among African Americans and other racial-ethnic groups, appear to play a role in interfering with weight loss efforts.
-Sedentary life style, which can contribute to the development of obesity, has been reported by 44 to 60 percent of Native American men and 40 to 65 percent of women.
-African Americans and whites report that they exercise less as they get older, however, African American women of all ages report participating in less regular exercise than white women.
-African American men, age 45 and older, report less regular exercise than white women.
Q: Describe the impact that obesity has on health and productivity costs.
-assocaited with 39 million lost work days, 239 million restricted days, 90 million bed days, 63 million physician visits
-Major contributing factor in workers’ comp injuries, Accounts for >9% of the total costs of work absenteeism, Costs U.S. companies $13 billion/year ($8 billion attributable to health care, $5 billion attributable to sick leave, life insurance, disability insurance, absenteeism, and presenteeism)
Q: How does obesity affect cost the most?
-obesity carries high costs in worker absenteeism
-Obesity and morbid obesity are associated with increased rates of work absenteeism, costing an estimated $4.3 billion per year in the United States, reports a study in the December Journal of Occupational and Environmental Medicine. The journal is published by the American College of Occupational and Environmental Medicine.The new study confirms the strong association between obesity -- especially morbid obesity -- and job absenteeism. The results also show some important differences by sex and occupational group, says a Newswise article on the study. The new cost estimates suggest that obesity accounts for more than 9% of the total costs of work absenteeism. "Quantifying these costs is important because such information will help employers assess the return on investment associated with interventions to reduce obesity," says lead researcher John Cawley, PhD, of Cornell University and the National Bureau of Economic Research in Ithaca, New York. The researchers used nationally representative health data to analyze the rates and costs of obesity-related absenteeism. Overall, 29% of men and women were obese, defined as a body mass index (BMI) of 30 or higher. This included morbid obesity -- BMI 40 or higher -- in 8% of women and 6% of men.
Q: Describe how diagnosis of diabetes has changed over the years.
-From 1980 through 2005, the number of adults aged 18-79 with newly diagnosed diabetes almost tripled from 493,000 in 1980 to 1.4 million in 2005 in the United States.
-Frequency of diabetes and obesity affecting all age groups
Q: What is the annual average cost of diabetes?
-Average annual health care cost for diabetic is $13,243 compared to $2,560 for a non-diabetic
-The total annual economic cost of diabetes in 2007 was estimated to be $174 billion. Medical expenditures totaled $116 billion and were comprised of $27 billion for diabetes care, $58 billion for chronic diabetes-related complications, and $31 billion for excess general medical costs. Indirect costs resulting from increased absenteeism, reduced productivity, disease-related unemployment disability, and loss of productive capacity due to early mortality totaled $58 billion. This is an increase of $42 billion since 2002.
Q: Describe the ethnic bias of diabetes.
-Diabetes has been reported to occur at a rate of 16 to 26 percent in Hispanic Americans and black Americans, aged 45 to 74, compared with 12 percent in whites (non-Hispanic) of the same age.
-Higher BMI predicts the risk for type 2 diabetes in Pima Indians. Type 2 diabetes affects about half of the Pima people.
-Among 15 American Indian tribes studied in Oklahoma, 77 percent of adults screened for diabetes are reported to be obese.
-Among Mexican Americans, obesity and type 2 diabetes are both increasing, unlike other risk factors of cardiovascular disease including smoking and blood pressure, which are declining.
Q: What was the U.S. cost of diabetes in 2007?
-Total annual cost estimated at $174 billion (32% increase from 2002)
-Annual health care cost for diabetic is $13,243 (vs. $2,560 for a non-diabetic)
-One out of every five US health care dollars spent caring for someone with diagnosed diabetes!
-Total annual increase in DM costs is equivalent to >$8 billion more each year since 2002. Average annual health care cost for diabetic is $13,243 compared to $2,560 for a non-diabetic
Q: How has physical activity changed in the past 15 years?
-Walking trips declined 40%, Children walking to school dropped 60%, Workers have more sedentary jobs, Leisure includes more screen time
Q: How have dietary practives changed over the past 20 years?
-Calories rose 22% from 3200 to 3900 per day
-Snacks as portion of daily calories increased >50%
-Proportion of food eaten away from home doubled
-Food processing has replaced complex grains with refined carbohydrates and simple sugars
-Portion sizes grown by 25 – 50%
Q: What effect does the environment that has been build and work-life affect obesity?
-Housing developments far from amenities, Fewer safe or accessible walking trails, Limited access to open space, Long commutes and working hours, Sedentary, high stress jobs, Limited amount of sleep
Q: What effect does advertising have on obesity?
-Unlike restrictions on alcohol and tobacco marketing, Food advertising is basically unrestricted, Lacks information on nutritional value or portion size
-2005 IOM committee on food marketing to children and youth found that $900 billion dollar food beverage and restaurant industries spent $10 billion on marketing to children.
-New products introduced into market from 1994 to 2004 were disproportionately marketed to children and disproportionately high in calories and low in nutrients
Q: What are the top 3 underlying causes of death?
-tobacco use, poor diet and inactivity and excess alcohol use are the top 3
-These behaviors contribute to heart disease, cancer, and stroke – the top three leading causes of death in the US. ½ of health status is due to what we do every day
Q: What has led to our serious economic threat?
-INC in poor lifestyle practices + drives worsening health status + raises health and productivity costs
-Adverse impact on individuals (disability), business (decrease profits/layoffs/closures), economy (decreased purchase of goods and services) and state (decreased tax revenues).
Q: What are some worksite solutions that will work?
-Understanding the Production of Disease: Identify health risks and prevent disease and its complications
-Identifying Persons At Risk: Determine those with factors linked with becoming ill or contracting a disease
-Intervening to Promote Healthy Behaviors: Assist at-risk persons in lowering their risk and disease
-Executing An Effective Engagement Strategy: Communicate health as a priority, build awareness, generate participation and reinforce healthy behaviors
Q: What are some examples of modifiable risk factorsWeight, including obesity?
-High blood glucose, High blood pressure, Abnormal lipid or cholesterol levels, Poor dietary practices, Physical inactivity, Smoking, Sleep problems
Q: What are the three groups that we should view the population in?
-Truly Healthy are in shape, practice healthy lifestyles, and take advantage of your perks, such as gym memberships
-Already Ill require ongoing clinical treatment with medication and disease management in the absence of cure
-Ticking Time Bombs appear healthy, but are not
Q: What is the annual cost of treating hyperlipidemia, hypertension, and diabetes?
-Annual cost of treating hyperlipidemia: $2,640 per patient, Annual cost of treating hypertension: $1,825 per patient, Annual cost of treating diabetes (medical costs only): $6,649 per patient
Q: What percent of people are unaware that they are at risk for hyperlipidemia, hypertension, pre-diabetes and diabetes?
-hyperlipidemia (41%), hypertension (37%), pre-diabetes (50%) and diabetes (29%)
Q: Describe metabolic syndrome.
-simple to test-fasting glucose, triglycerides, waist girth, BP, HDL cholesterol
-simple to determine-persons with unfavorable results in three or more categories have MetS and are at risk for poor health
-simple to implement-easy to understand, non-invasive tests inexpensive to obtain, personalized focus and worksite promotion reduce risk
Q: What percent of the US workforce has MetS?
-~1/3 of the US workforce has Metabolic Syndrome (MetS)
Q: What is the importance of diagnosing MetS?
-MetS has a higher probability of adverse health events than those without it
- Reducing MetS can impact costs by lowering the risk for chronic disease such as diabetes and heart disease, Programs that targets Metabolic Syndrome successfully can have an enormous impact on health care costs by helping to lower the risk for chronic disease such as diabetes and its complications.
Q: What is the effect of an integrated strategy that combines a PH approach with traditional health care delivery?
-Promotes health awareness (Encourage interest and sustained participation and Promote practices and policies that improve health)
-Provides primary prevention (Best defense is good offense – Don’t gain & stay active, Recognize health risks and refer to targeted lifestyle support)
-Provides secondary prevention (Timely referral to medical treatment when indicated, Increase adherence and monitor for co-occurring conditions)
Q: What are the goals of an integrated strategy?
Goal #1: Increase personal awareness and accountability for health
Goal #2: To increase the everyday practice of healthy lifestyle behaviors
Goal #3: To increase the proportion of the workforce that remains healthy and disease free
Q: What impact does reducing blood pressure among commercial drivers have?
-Objective: Determine if a health promotion and blood pressure (BP) management program improved outcomes among drivers employed by a self-insured utility company
-Results: Uncontrolled BP reduced 50% (from 40.7% to 17.2%), Improvement consistent across subgroups defined by diabetes, obesity, and use of BP medication
-Conclusions: An education program improved control of BP among commercial drivers, improving their health and safety, and reducing the number at high risk of medical disqualification.
Q: Describe the retail grocer’s health improvement program case study.
-Background: Grocer faced rising health care costs and potential reduction of benefits
-Actions: Implemented health promotion model for their stores , Integrated wellness offerings with benefits, Placed onsite health specialists throughout stores ½ day/wk
-Results: By end of year 2, has recorded annual decreases in costs, 6.5% decline of health care costs in 2007 from 2006, Increased market share by promoting health to patrons
Q: Describe the combined health improvement program and onsite center case study.
-Background: Occupational and non-occupational care provided onsite since 1993. Several wellness programs implemented to address specific health risks
-Action: Stretching program called “Muscles Matter” implemented prior to shift to decrease muscle strains.
-Results: 49% physical improvement in the participants, Overall participant response of 95% when asked “does your body feel stronger and more flexible”
Q: What is the value of the TotalCare Programs?
-Similar programs $3-$6:$1 ROI over 2 to 5 year period
-Requires sufficient intensity, At least one year in duration, 25% savings in absenteeism, disability, group health and workers compensation
-Multi-component programs with best returns, Include health marketing and incentives to engage, Promote skill building and integration with clinical care, Employer policies and environment aligned with health
Q: Why is the ROI significant in these programs?
-Identifies those “at risk” and refers them to lifestyle support, Decreases risk factors that results in decreased disease, Lowers overall medical costs due to timely referral, Creates healthy culture and supports sustainable change, Increases productivity by cutting lost work time, Conveys pledge to employee health that boosts retention, Easy to implement and it works!
Q: What are the different types of variables?
-nominal, dichotomous (binary), ordinal (ranked), continuous (dimensional), ratio
Q: Describe nominal variables.
-naming or categorical variables that have no measurement scales
-examples include blood groups (A, B, O), occupations, food groups or skin color
Q: Describe dichotomous (binary) variables.
-a variable with only two levels (say abnormal and normal skin color), important for interpreting data but not for the statistical analysis
-examples include well/sick, living/dead, and normal abnormal
Q: Describe discrete variables.
-dichotomous variables and nominal variables are examples of discrete variables because the different categories are completely separate from each other
Q: Describe ordinal (ranked) variables.
-variables that can be characterized in terms of three or more qualitative values that have a clearly implied direction from better to worse, these data are not measured on a measurement scale
-it is possible to see the relationship between two ordinal categories and know whether one category is more desirable than another
-examples include satisfaction with care (very satisfied, fairly satisfied, or not satisfied), edema (1+-4+)
Q: Describe continuous (dimensional) variables.
-data measured on continuous measurement scales, contains more info then ordinal because continuous data shows the position of different observations relative to each other but also show the extent to which one observation differs from another
-examples include height, weight, systolic and diastolic blood pressure and serum glucose
Q: Describe ratio variables.
-the variables derived from a continuous scale that has a true 0 point
-examples include K temperature
Q: Describe risks and proportions as variables.
-risk is the conditional probability of an event, both share some characteristics of a discrete variable and some of a continuous variable, both are variables created by the ratio of counts in the numerator to counts in the denominator
Q: What are the different measures of central tendency?
-mode, median and mean
Q: What are the different measures of variability (dispersion)?
-percentiles, range, interquartile range, variance, mean deviation, and standard deviation, can be measured based on percentriles (percentiles, range and IG range) or based on the mean (mean deviation, variance, standard deviation)
Q: Describe percentiles.
-sometimes called quantiles, the percentage of observations below the point indicated when all of the observations are ranked in descending order
Q: Describe interquartile range.
-the distance between the 75th and 25th percentile, because of central clumping, the IQ range si usually considerably smaller than half the size of the overall range of values
Q: What is the advantage of using percentiles?
-they can be applied to any set of continuous data, even if the data do not form any known distribution
Q: Describe mean deviation.
-the average of the absolute value of the deviations from the mean (= sum(abs(Xi-Xbar))/(N)), does not have mathematical properties that enable many statistical tests
Q: Describe variance.
-variance = (sum((Xi – Xbar)^2)/(N-1)),
Q: Define degrees of freedom.
-the number of observations in a data set that are free to vary when the parameters of the data set have been established
Q: How is standard deviation calculated?
-sqrt(variance) = sqrt(sum((Xi – Xbar)^2)/(N-1)), the area under the curve represents the probability of all of the observations in the distribution
Q: What are the different probabilities associated with the different standard deviations for a normal distribution?
-one standard deviation = 68%, two standard deviations = 95.4%, 1.96 standard deviations = 95%
Q: Define sensitivity.
-ability of a test to detect a disease when it is present, calculated as a/(a+c) (TP/(TP + FN))
-if have low sensitivity, then it fails to detect disease and these subjects appear in FN
Q: Describe false-negative error.
-the rate that subjects appear as FN, calculated as c/(a+c), sensitivity + false-negative error = 1
Q: Define specificity.
-ability of a test to indicate nondisease when no disease is present, calculated as d/(b+d) (TN/(FP + TN))
-if a test is not specific, it falsely indicates the presence of disease in nondiseased subjects, placing them in FP
Q: Describe false-positive error.
-rate at which subjects appear in b, calculated as b/(b+d), specificity + false-positive error = 1
Q: Describe positive predictive value (PV+).
-measure indicates what proportion of the subject with + tests results had the disease, calculated by a/(a+b)
Q: Describe negative predicitive value (PV-).
-measures what proportion of the subjects with negative test results did not have the result, calculated by d/(c+d)
Q: What is type I and type II error?
-type I-error that occurs when data lead one to conclude that something is true when it is not true, type I error is called alpha error and false-positive error
-type II-error that occurs when data lead one to conclude that something is false when it is true, type II error is called beta error and false-negative error
Q: How is the probability of an “and” probability calculated?
-P (a and b) = p(a given that b) * p(b)
Q: Define odds.
-is the probability that something will occur divided by the probability that it will not occur (or the number of times it occurs dividied by the number of times it does not occur), only describe a variable that is dichotomous
-can be used to calculate probability (probabilityX = (odds of outcome X)/(1+odds of outcome X)
Q: Define null hypothesis.
-states that there is no real (true) difference between the means (or proportions) of the groups being compared (or that there is no real association between two continuous variables
Q: Why is a null hypothesis used?
-it is easier to disprove an assertion to prove that something is true, if the data is not consistent with the null hypothesis, the hypothesis is rejected and the alternative hypothesis is accepted
Q: How is the null hypothesis tested?
-must first establish the alpha level, which is the highest risk of making a false-positive error that the investigator is willing to accept, usually set the p = 0.05 saying that the investigator is willing to run a 5% risk of being in error when rejecting the null hypothesis
Q: How is the p value for the data calculated?
-perform a suitable statistical test of significance on the data
-p value gives the probability of obtaining the observed result by chance rather than as a result of a true effect, when the p value is sufficiently remote/small, the null hypothesis is rejected
Q: What can and cannot a p value tell you?
-can reject the null hypothesis or not reject the null hypothesis, does not prove anything nor does it let you accept the hypothesis
Q: What is the difference between a t-test and z-test?
-t-tests compared differences between means whereas a z-test compares proportions
Q: How is standard error calculated?
-SE = SD/sqrt(N)
Q: How is the critical ratio calculated?
-critical ratio = parameter / SE of that parameter = difference between two means/SE of the difference between the two means
Q: When are t-test used?
-used to compare the means of a continuous variable in two research samples, such as a treatment group and a control group, this is done by determining whether the difference between the two observed means exceeds the difference that would be expected by chance from the two random samples
-use student t test if the samples are from two different groups, use paired t-test if the samples are from the same group (but say from different times, before and after treatment)
Q: When are chi-square tests used?
-test for the independence of two variables in a contingency table, seeks to develop a statistical expression that predicts the behavior of a dependent variable on the basis of knowledge of one or more independent variables
-if chi square is large, then reject the null hypothesis
-chi-square = sum[((O-E)^2)/(E)]
Q: How are the degrees of freedom calculated for a table?
-df = (R-1)(C-1)
Q: Define epidemiology.
-The study of factors that influence the occurrence and distribution of disease in human populations
-The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to the control of health problems.
Q: What are the objectives of epidemiology?
-Identify the cause, or etiology, of the disease and its risk factors (ie. factors that increase a person/population’s risk of disease)
-Determine the extent of disease found in the community
-Study the “natural history” and “prognosis” of the disease
-Evaluate existing and new preventive and therapeutic modes of health care delivery
-Provide the foundation for developing public policy and regulatory decisions regarding environmental problems
Q: Define natural history of disease.
-progression of a disease in the absence of medical or public health intervention
Q: Define prognosis.
-prediction of how a disease will progress
Q: What are the risk factors for disease?
-BEINGS model (biological, envrinomental, immunologic, nutritional, genetic, social and spiritual factors)
Q: What are the four factors that are involved in the natural history of a disease?
-host factors, agents of disease, environment, vector
Q: Describe the host factors role in natural history of disease.
-individual’s ability to adapt to stressors of the agent of disease (ie. resistance), includes nutritional status (malnutrition), genotype, immunocompetency, social behaviors
Q: Describe the agents of diseases role in natural history of disease.
-Biological (infectious organisms (bacteria, virus, prions), allergens, foods)
-Chemical (toxins (eg. lead, mercury), dusts (eg. silica, coal))
-Physical (kinetic energy (eg. MVA, gunshot), radiation, heat / cold)
-Social and psychological stressors (participation in or witnessing of traumatic events (eg. 9/11), overcrowding)
Q: Describe the environments role in natural history of disease.
-influences probability and circumstances of contact between host and agent, poor sanitation in restaurant = increase risk of infection with Salmonella by patrons
-may involve social, political, and economic environmental factors
Q: Describe the vectors role in natural history of disease.
-not always involved, considered a transmitter of disease, requires specific relationship to the agent, environment, and host
-examples include insects (eg. mosquito, tse-tse fly), arthropods (eg. ticks), animals (eg. raccoons), groups of humans (eg. vendors of illicit drugs), fomites (ie. inanimate objects – needles, door knobs)
Q: Where do we want to intervene?
-at the mechanism of injury, in the example given in class with skiing and head injuries, want to promote helmet use which has been proposed to DEC number of head injuries, but this may INC number of risky behavior
Q: What is incidence rate?
-is a type of epidemiologic measure of frequency, the number of incident cases over a defined study period, divided by the population at risk at the midpoint of that study period
Q: What is numerator data?
-what is being defined or the outcome of interest, examples include deaths, cases of disease, health events
Q: What are the data sources that can be used to obtain numerator data?
-injury or disease surveillance systems (National Notifiable Disease Surveillance System), disease registries, survey data: (National Center for Health Statistics: NHANES, NHIS, Behavioral Risk Factor Surveillance System (BRFSS)), cross-sectional and observational studies
Q: What is denominator data?
-Defines the population at risk, Often the most difficult part of epidemiology, Sometimes requires creative thinking, Very important to demonstrate methodology of defining the “at risk” population in a study to validate correct population was examined
Q: What characteristics must be met for the denominator?
-all members of the pop must be at risk for the outcome of interest (should be able to be included in the “numerator,” ex: women at risk for cervical cancer must have a cervix)
-pop should be relevant to question asked
-pop described in adequate detail so it is a useful basis for judging to whom it applies
-samples studied should adequately represent the pop from which it is derived
Q: What are the data sources that can be used to obtain denominator data?
-Vital statistics registration systems (International census data (World Health Statistics Annual), US Census, US Vital Statistics System (birth and death certificates), State, regional, and local VS systems) and survey data
Q: What are the three different types of causal relationships?
-sufficient cause, necessary cause, risk factor
Q: Define sufficient cause and give an example.
-always precedes a disease, if present, disease will always occur, very rare in medicine
-ex: homozygous genetic disorders (Tay-Sachs disease)
Q: Define necessary cause.
-always precedes a disease, must be present for a disease to occur, but may be present without the disease occurring, synonym: “prerequisite”
-ex: person must have infection with M. tuberculosis to have TB
Q: Define risk factor as a causal relationship.
-if present and active, clearly increases the probability of a particular disease, neither a necessary or sufficient cause
-examples: smoking and lung cancer, skiing and head injury, obesity and type 2 diabetes mellitus
Q: Define association.
-relationship between two or more events, characteristics, or other variables
-there are different types of association (statistically significant, directly causal, indirectly causal, noncausal)
Q: Describe statisticall significant.
-unlikely due to chance alone
Q: Define directly causal.
-factor exerts its effects without intermediary factors, gunshot to heart leads to death
Q: Define indirectly causal.
-factor exerts effect via intermediary factors, educational level leads to better health via improved health knowledge, increase motivation, and increase financial resources
Q: Define noncausal.
-statistically significant association but temporal relationship is incorrect or another factor is responsible for presumed cause and presumed effect
-baldness associated with risk of CAD, but not causal as may postcede CAD and both baldness and CAD risk are functions of age and gender
Q: How is cause and effect determined?
-risk factor present more often in persons with disease than those without
-large enough assoc to be statistically significant (ie. not by chance alone)
-Investigation of temporal relationship (suspected causal factor must have occurred or been present before the disease developed)
-Elimination of known alternative explanations (proper research design aids in elimination of bias and confounders (eg. randomization, blinding), never able to fully eliminate ALL possible explanations)
Q: What are the criteria that must be true for statistically significant association to be more likely causal?
-Strength of association
-Consistency of association
-Specificity of association (no risk factor present, then no association)
-Biologic plausibility-smoking to lung cancer (smoking leads to epithelial damage)
-Dose-response relationship present (Increase disease risk with greater exposure to risk factors, ex: increase pack-years = increase risk lung CA)
Q: Define prevalence.
-# of persons in a defined population who have a specific outcome of interest (eg. disease, condition) at a point in time, Think of a “snap-shot,” Synonym: “point prevalence”
Q: Define periodic prevalence.
-# of persons with outcome of interest during a specified time interval, PP = prevalent cases + incident cases during specified time interval, not often used
Q: Define prevalence rate.
-PR = (# of existing outcomes of interest at a specific time)/(population at risk at a specific time)
-not a true rate but a proportion, expressed as a percentage, the % of a population that has a defined disease or condition at a point in time, Allows comparison of different diseases within a specific population or comparison of a specific disease between different populations
Q: Define incidence.
-# of new occurrences of the outcome of interest in the study population during the time period examined, Also called “incident cases”
Q: Define incidence rate.
-IR = (# of new events in a specified period)/(population at risk in the time period)
-Provides a sense of how quickly a disease is spreading, Allows comparison over different time periods
Q: Define cumulative incidence.
-the total number of incident cases in a population over a specified period, incident cases during the study period would be included in the cumulative incidence measure but not in the point prevalence
Q: Define ratio.
-comparison of any two values, range from 0 to infinity, numerator and denominator may be unrelated
Q: Define proportion.
-comparison of a part to a whole, range from 0-1, numerator must be included in the denominator
Q: Define risk.
-a proportion of an initially disease free population that develops disease during a specified period of time, synonyms include attack rate (used in outbreak investigations) or cumulative incidence)
-is (#new cases during specified period)/(size of population at start of period at risk)
Q: Define odds.
-odds in favor of an event = (probability that event will occur)/(probability that event will not occur) = (prob)/(1-prob)
Q: How do odds and odds ratio differ?
-This differs from “odds ratio” which is a comparison, or ratio, of already calculated odds. Do not confuse “odds” with “probability” or “odds ratio.”
Q: What is the use of measuring prevalence?
-useful for chronic diseases or disease of long duration, helps to estimate “disease burden” in a population
Q: When calculating incidence, do you count the cases that are already present?
-NO, do not include the cases that are already present, only new cases in the time period
Q: Define incidence rate.
-what is happening from time period to time period (ie. year to year), how quickly disease occurs in a population (ie. “force of morbidity or mortality”)
Q: Define risk.
-AKA Cumulative Incidence (CI), Incidence Proportion, what happens over an accumulation of time (ie. “cumulative incidence”), What proportion of the population will develop the disease during a defined time period
Q: What does epidemiologic research define?
-New diseases (eg. HIV/AIDS, SARS, West Nile virus, CA-MRSA), Populations at risk for disease, Possible causative agents of disease, Factors/behaviors that increase risk of disease, The relative importance of a factor relative to the disease
-Ruling out factors that may contribute to disease, Evaluation of therapies and interventions, Guide in the development of PH measures and policies/regulations, Guide the development of effective prevention strategies
Q: What is the purpose of the scientific method?
-Describe the phenomena, Explore relationship among phenomena, Explain phenomena and increase understanding, Predict cause of and relationships among phenomena, Control phenomena
Q: What are the steps for studying the scientific method and how does that apply to the clinician and epidemiologist?
-steps-data base -> assessment -> hypothesis testing -> action
-clinician-H&P -> differential diagnosis -> diagnostic studies -> treatment
-epidemiologist-surveillance, descriptive epidemiology -> inference -> analytical epidemiology -> community intervention
Q: What are the two different types of epidemiologic studies?
-descriptive and analytic
Q: What are the steps in descriptive epidemiologic studies?
-case report, case series, incidence, cross-sectional, ecologic
-determines distribution of disease
-look at who was affected, where they were affected and when they were affected and used that information to determine how and why
Q: What are the steps in analytic epidemioligc studies?
-experimental (clinical trial and community) and observational (cohort-prospective or retrospective), case-control, and other
-determines determinants of disease
Q: Compare descriptive and anyltical studies.
-in descriptive, less is known, search for clues and hypothesis generation only, in analytical, more is known, the clues are available and hypothesis can be generated and tested
Q: Describe descriptive studies.
-focus on person, place, time, displays patterns of occurrence
-Use program planning, health policy prioritization, gathering clues, and Hypothesis generation!!!!!!!!
Q: What are the different types of descriptive studies?
-case report/case series, descriptive incidence, cross-sectional (descriptive prevalence), ecological (correlational)
Q: Describe case report/case series.
-Profile of a case or case series (“anecdotes”) (from clinical data), foundation of all epidemiologic means (where medicine and epi come together), Generate new hypotheses, Interface: medicine and epidemiology, Numerator data only, No measure of disease occurrence (frequency)
ex: description of first 100 persons with SARS
Q: Describe descriptive incidence.
-Patterns in occurrence of incident cases (often from surveillance data), Defined population (use denominators, often from census data), Specified period of time, Optionally, distribution of cases stratified by factors of interest
Q: Describe cross-sectional (descriptive prevalence).
-"Snapshot" of well-defined population, Surveys or mass screenings of individuals
-Uses include determination of prevalence of risk factors, determination of frequency of prevalent cases, measuring current health status and planning
-examples include NHANES, BRFSS
Q: What are the advantages and disadvantages of cross-sectional?
-Advantages include Quick, inexpensive, useful
-Disadvantages include Uncertain temporal relationship between risk factors and dz, late look bias (Neyman bias), length bias
Q: Describe late look and length bias.
-Late look bias = mild, slowly progressive cases of disease preferentially detected in survey b/c pts with this form live longer, while severe cases result in death and can go undetected
-Length bias = milder, more indolent cases detected disproportionately in population screening programs since more aggressive cases have already resulted in death or progressed to symptomatic disease phase
Q: Describe ecological (correlational).
-Exposures / risk factors and disease are accumulated at an aggregate level (ie. country) not individual surveys or screenings, Unit of observation is a population
-Types include cross-sectional and longitudinal
Q: What are the advantages and disadvantages of ecological?
-Advantages include Quick, inexpensive, data readily available, worries about the community as a whole and not the individual
-Disadvantage: “ecologic fallacy”
Q: Define ecologic fallacy.
-Ecologic fallacy = use of ecologic (aggregate population) data to draw inferences about causal realtionships in individuals, recall that not all statistically significant associations meet the criteria for causality
-A lot of beer is consumed per capita in the Czech republic. There is a high incidence rate of rectal cancer is the Czech republic. Fallacy would be to state that the high volume of beer consumption causes rectal cancer to a Czech national. Cannot translate ecological data to the individual.
Q: Describe analytical studies.
-Assess determinants of disease, Focus on risk factors, causes, Analyze distribution of exposures and disease
-Uses include Looking for / quantifying associations, Hypothesis generation, and Hypothesis testing!!!!!!!!!
Q: What are some examples of descriptive and analytical studies?
-descriptive-description of 1st 100 persons with SARS, trends in incidence of malignant melanoma, Sweden, prevalence of seat belt use, US, 2007, cigarette sales vs lung cancer death, US Nat’l data, 2007
-analytical-risk factors for SARS, malig melanoma and cumulative sunlight exposure, Sweden, seat belt use by exposure to PSAs, cigarette smoking and lung cancer
Q: What are the different types of analytical studies?
-experimental/interventional-clinical trials, field trials, community trials, outcome-based enrollment (i.e. outcome precedes investigator)
-observational-cohort studies (prospective, retrospective), case-control studies exposure-based enrollment (i.e. investigator precedes outcome)
Q: Describe observational studies.
-Nature prevails (ie. no intervention assigned by researchers), Examines the associations between risk factors and outcomes
-Two main types: Cohort and Case-control, Dimensions are Directionality, timing
Q: What is the difference between cohort and case-control studies.
-cohort study starts before exposure and see if there is a disease associated with that exposure, case-control starts with the disease and see if there is a common exposure
Q: Describe cohort studies.
-“Motion picture study” (Paffenberger, 1988), Follows a cohort (eg. a clearly identified group to be studied who share a common characteristic) through time, Cohorts defined by exposure therefore, “exposure-based enrollment” of subjects
-Most powerful observational study and gold standard for studying the association of risk factors/exposures and outcomes
Q: What are the different types of cohort studies?
-prospective (uses people)-observer begins study prior to subject accumulation, cohorts are identified by exposure and non-exposure when the study begins, ex: Framingham Heart Study
-retrospective (historical data, medical records)-observer begins study after exposure and outcomes have occurred (?), use historical data (eg. medical records) to identify a cohort, then “follows” to outcome based upon data review, exposure must always temporally precede outcome
Q: What are the steps in cohort studies?
1. Identify exposed group of concern or enroll entire pop
2. Identify appropriate unexposed comparison group, if necessary
3. Follow through time and document disease among exposed and unexposed groups
4. Calculate risks or rates of disease
5. Calculate RISK RATIO (RR), also called RELATIVE RISK
Q: For a 2X2 table, what is the convention for the variables of the table?
-by convention the exposure + group is on the vertical axis, disease group is on the horizontal axis
Q: What measures of frequency are used for cohort studies?
-Think Incidence!! Allows direct calculation of risk, use risk and incidence rate
Q: What measures of association are used for cohort studies?
-Think relative risk (RR), Risk ratio if cumulative incidence study, Rate ratio if person-time follow-up study
-risk of disease in exposed (Re)/Risk of disease in unexposed (Ro) = relative risk
-“Persons drinking water from the Southwark water source are 14.2 times more likely to develop cholera compared to persons drinking water from the Lambeth water source.”
Q: What are the advantages of a cohort study?
-Allows for complete description of experience after exposure
-Clear temporal sequence of E and D
-Well-suited for RARE EXPOSURES
-Can measure incidence of disease
-Allows direct calculation of risks
-Can study multiple effects (risks and benefits) of an exposure
-Understandable by non-epidemiologists
Q: What are the disadvantages of a cohort study?
-Many subjects needed for rare disease
-Follow-up: logistics, losses
-Exposure can change over time
-Prospective: time-consuming, costly, observation can influence behaviors
-Retrospective: requires suitable records
-Changes in practice, usage, exposures may make findings irrelevant
Q: What are the sources of error for a cohort study?
-Bias (differential error) = any trend in collection, analysis, interpretation, publication, or review of data that can lead to conclusions that are systematically different from the truth
-Confounding = a factor that is associated with the outcome and the exposure that may skew results
Q: What is one of the problems with cohort study?
-loss of follow up, rule of thumb: >30% invalidates study due to lack of internal validity, occurs in many study types but especially in long-term prospective cohorts
Q: What are the best candidates for prospective study?
-licensed professionals (but, MDs notoriously unreliable!!!), workers, entire company, unions, veterans, an entire community (Framingham)
Q: Describe selection bias.
-occurs when allocation to a study or particular study group is influenced by individual characteristics that also influence the probability of the outcome, can negate the internal validity of a study (kill it!!!)
Q: Describe information bias.
-misclassification of exposure or outcome
-ex: person claims to be a “non-smoker,” but actually smokes 5 cigarettes per day (would increase the D+ rate found in the E- group)
-ex: pathologist misses multiple diagnoses of lung CA in a smoking study (would decrease the overall D+ rates)
Q: Describe case-control studies.
-“Flashback studies” (Paffenberger, 1988), Retrospective assessment of differential exposure between 2 comparison groups, Case: (D+) has outcome of interest, Control: (D-) does not have outcome
-Outcomes precedes investigation, therefore outcomes-based enrollment
Q: What are the case-control studies steps?
1. Identify cases of disease of concern
2. Identify appropriate non-diseased comparison group (“controls”)
3. Document exposures among cases and controls
4. Calculate odds ratios (OR’s)
Q: Describe the control group in a case-control study.
-the Critical design issue, Selected from the exact same population as the cases
-Controls provide an estimate of prevalence of exposure in population and an “Expected” prevalence of exposure among cases if no association
Q: Describe the guidelines control selection.
-No optimal group for all situations
-Controls should Not have the disease being studied, Represent population from which cases arose, Represent persons who, if developed disease, would have been a case in the study, Be selected independently of exposure, Matched: demographically, geographically, temporally
-good candidates (hospital-based, neighbors, friends
Q: What is the direction of time and study in a case-control study?
-Direction of study is retrospective, opposite the direction of time
Q: What are the measures of association measured for case control study?
-use odds ratio, odds ratio = odds of exposure among cases/odds of exposure among controls
-A person exposed to L-tryptophan pills manufactured by Showa-Denka Co. is 57.5 times more likely to develop EMS than those exposed to pills manufactured by other companies.
Q: What are the advantages of case control studies?
-Quick and inexpensive
-Well-suited for RARE DISEASES and diseases with long latency
-Can study multiple exposures
-Requires fewer subjects at entry
-Few ethical problems
Q: What are the disadvantages of case control study?
-Unable to directly measure disease risk
-Determination, selection, and enrollment of appropriate control group may be difficult (potential selection bias)
-Relies on recall or records for info on past exposures (potential recall bias)
-May be difficult to determine that ‘cause’ preceded ‘effect’
-Unsuitable for rare exposures
-Less familiar to non-epidemiologists
Q: Desccribe recall bias.
-Major source for potential bias, Cases are more likely to remember and/or report potential exposures than controls, increase E+ cases => increase odds of exposure in cases (numerator of the OR) => increase OR (may be interpreted as an increased association between exposure and disease)
Q: Describe experimental studies.
-Explore the associations between interventions and outcomes, Assign exposure randomly, follow over time and monitor for disease
-Types include Randomized clinical trial, Randomized field trial, Community trial
Q: Why is experimental studies considered the gold standard in alalytical research?
-provide the strongest evidence for disease causation
-design can more effective rule out with greater certainty factors that may confound a cause and effect relationship
-limit bias via blinding and placebo-controlling
Q: Describe community trials.
-Intervention group is a community instead of individual
-appropriate design for diseases originating from social conditions and are amenable to group and individual intervention
Q: Describe RC field trials.
-Study population is at risk, but disease free, study “real world” population
-generally intervention studied is preventive rather than therapeutic (ex: polio vaccination, isoniazid to prevent reactivation of TB)
-administration of intervention with subsequent determination of the rate of disease in each group over time
Q: What are the limitations of the RC field trials?
-Huge undertaking, major logistical and financial considerations, Randomization very difficult in the general population
Q: Describe RCCTs.
-Compares clinical interventions between treatment and control group <NELWINE>-May detect small associations not noted in observational studies
-Generally the final study design in derivation in causal relationships
Q: What are the challenges for RCCTs?
-Equipoise-investigator needs to be ambivalent to the study
Q: For RCCTs, how are populations to be studied selected?
-Internal validity – are treatment and control groups adequately matched (make sure there is no outlier INC in one group)
External validity – how generalizable are the results to the larger population (whether study pop is representative of actualy population)
-Adequate “n” (sample size) to “power” the study to detect an association not related to chance alone
-Loss to follow-up, “Willing and able,” Hawthorne effect (people tend to do things they do not normally do)
Q: Describe compliance for RCCT.
-Better termed “adherence,” Treatment group adhering to the intervention regimen?
-“Intention to treat” (efficacy (does drug give effect) vs. effectiveness (does intention to take drug cause desired effect), affects internal and external validity)
compliance measurement protocols (pill counts, self reporting, biochemical markers)
Q: What is the measure of association used in studying RCCT?
-relative risk = (a/(a+b)) / (c/(c+d))
-risk difference (RD), also called attributable risk (AR), expressed as a number Re – Ro, RD = 0 (no risk), RD > 0 (harmful), RD < 0 (protective)
-= (Re-Ro)/Re = attributable risk % (AR%) = (RR-1) / RR = (OR-1)/OR
-population attributable risk (PAR) and PAR %
Q: Describe AR%.
-Also called “AR% in the exposed,” Based upon the 2x2 table: (% of “a” in which exposure caused the disease)
-“Among those with the exposure (E), what % of the total risk for the disease (D) is due to E?”
-ex: Among smokers, what % of the total risk for fatal lung cancer is due to smoking?
Q: Describe PAR.
-= Risk of total population (Rtotal) – Ro, expressed as a number
-ex: “Among the general population, how much of the total risk for fatal lung cancer is due to smoking?”
Q: Describe PAR%.
-= Rtotal – Ro / Rtotal, Based upon the 2x2 table: (% of a+b for whom exposure caused disease)
-“Of all the people with the disease in a population, that proportion for whom the exposure is the cause of the disease.”
-ex: “Among the general population, what % of the total risk for fatal lung cancer is due to smoking?”
Q: What are some other measures of association?
-Absolute risk reduction (ARR) = Re – Ro
-Relative risk reduction (RRR) = Re – Ro / Re
-Number needed to treat (NNT) = 1 / ARR, “The number of patients who would need to receive a specific type of treatment in order for one patient to benefit from the treatment.”
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