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Lecture 4 PH Epidem - Lecture 4 Epidemiology II Statistics HIV Overview Communicating data Epidemiological principles incidence prevalence Types of

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Lecture 4 Epidemiology II Statistics HIV
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Overview Communicating data Epidemiological principles – incidence, prevalence Types of Studies: retrospective, prospective - Intervention - Cohort - Case Control
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Definition of Epidemiology Epidemiology is the study of the distribution and determinants of disease frequency in human populations – meaning: Define disease Measure frequency Do this through examining data
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Define the Disease Some diseases need blood tests or stool cultures to verify diagnosis Some diseases are hard to define – Flu Sometimes definition changes as more is learned – e.g. AIDS
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Article: Translation Matters in Choices on Data Format in which data is presented can have big impact on health care decisions How doctors present the numbers effects decisions Yet patients are different and respond to different presentations Role also for Journalists and presenting information…
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Article: Translation Matter… continued Ex. Relative risk reduction of 50% can be shown by: Risk goes from 20% to 10% or Risk goes from 4% to 2%. Both statistics say the same thing – 50% reduction but the first sounds much more impressive.
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Understanding the Data: Disease Frequency Count number of people with disease and relate to the population at risk (PAR) PAR (denominator) may be total population or exposed population, or one gender or age group; often comes from census Two ways to measure frequency: Incidence – number of new cases Prevalence – number of existing and new cases Incidence is used for studying causes of disease
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Incidence and Prevalence Incidence and prevalence are related depending upon how long people live with the disease If the disease kills quickly => Incidence increases while prevalence decreases In chronic diseases, prevalence increases while incidence decreases. How about infectious diseases?
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Incidence and Prevalence, cont. If causes or risk factors increase, incidence and prevalence increase If ability to diagnose increases, incidence and prevalence increase Prevalence depends on incidence and prognosis Changes in incidence and prevalence could just mean better reporting/diagnosis
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Incidence Rate Incidence is the number of new cases of a disease or condition during a specific time period # of new cases in a specified time period population at risk during this period
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Prevalence Prevalence is the total number of existing and new cases at a given time. # of existing cases + new cases population at risk
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Kinds of Epidemiologic Studies Human studies only Goal is to determine at least an association between an exposure and a disease or other health outcome – prefer to show causation May be prospective (begin now and follow into future) or retrospective (examines past relations between exposure and disease) Intervention study Cohort study Case-control study
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Intervention Study Closest thing to an experiment
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This note was uploaded on 01/24/2012 for the course 832 232 taught by Professor Marcibergen during the Spring '11 term at Rutgers.

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Lecture 4 PH Epidem - Lecture 4 Epidemiology II Statistics HIV Overview Communicating data Epidemiological principles incidence prevalence Types of

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