Unformatted text preview: TYPES OF STUDIES IN DIABETES EPIDEMIOLOGY : TYPES OF STUDIES BASED ON: : Purpose Time Cost Feasibility TYPES OF STUDY Observational ) ) Descriptive Analytical Cross-sectional - Retrospective - Prospective - Experimental A STUDY DESIGN FOR THE OUTCOMES OF DIABETES . Diabetes Morbidity (Complications) )) Mortality (Death) Economics Treatment TIME AND TYPES OF STUDY PAST Retrospective Cross-sectional PRESENT Prospective FUTURE Time CROSS-SECTIONAL STUDY Cross-sectional PRESENT Time ANALYTICAL STUDY A cross-sectional study: Privides a snap shot Is simple Provides associated factor CROSS-SECTIONAL STUDY What is different about: : DM Morbidity (Complications) )) Mortality (Death) How is it different about: CROSS-SECTIONAL STUDY Korea Japan Kuwait Israel England Canada Netheland Denmark Pittsburgh, USA Scotland Sweden Finland 0 Incidence /100,000 10 20 30 RETROSPECTIVE STUDY Determining differences in: : Life style Diet Reproductive on PRESENT Disease Medication PAST Family Hx Genetics Time RETROSPECTIVE STUDY: PROS & CONS
PRO CON Suitable for rare diseases Inexpensive Minimal ethical problems Short study time Small # of subjects Subjects need not volunteer Susceptable to selection & memory bias Inconsistency: definitions of symptoms or diseases may have been modified over time. Can not determine incidence Limitations in data Relative risk approximation : : PROSPECTIVE STUDY Retinopathy+ + PRESENT DM Future Risk factors??? Retinopathy - Time PROSPECTIVE STUDY: PROS & CONS
PRO Less variability to bias No recall necessary Incidence determined Relative risk accurate CON Consistent disease definitions & symptoms. Longer time Common disease only Expensive Ethical concern A high drop-out rate Volunteers needed A large # of subjects needed The Hawthorne-effect : TYPES OF STUDIES AND GOALS CROSS-SECTIONAL RETROSPECTIVE PROSPECTVE Understan d Estimate risk factors Validate risk factors Prevention-Control-Intervention-Education-Management - EXPERIMENTAL STUDY Animal Drug trials Human Randomized Clinical Trial: DPP : EXPERIMENTAL STUDY Exercise Outcome evaluation Random Selection Diet Drug EXPERIMENTAL STUDY Cross-over design CASE Outcome evaluation CONTROL ...
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