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Cohort Study Overview. Jeanne M. Clark, MD, MPH Division of General Internal Medicine. Defined Population. Exposed. Not Exposed. Non-random selection. Develops Disease. No Disease. Develops Disease. No Disease. Design of Cohort Studies. Examples: JHU Precursors Study
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Cohort Study Overview Jeanne M. Clark, MD, MPH Division of General Internal Medicine
Defined Population Exposed Not Exposed Non-random selection Develops Disease No Disease Develops Disease No Disease Design of Cohort Studies Examples: JHU Precursors Study Framingham Study Identify: Can start here: (less common)
2000 Defined Population Exposed Not Exposed Non-random selection Develops Disease No Disease Develops Disease No Disease 2001 2008 Prospective (Concurrent) Cohort Typically active, scheduled follow-up of some kind
1988 Defined Population Exposed Not Exposed Non-random selection Develops Disease No Disease Develops Disease No Disease 1998 2008 Retrospective (Non-Concurrent) Cohort Generally passive or post-hoc follow-up of some kind
Comparison of 4 Major Study Designs Goal or Feature RCT CS CC X-S • Estimate Prevalence F F F A+ • Estimate Incidence B- A+ F F • Prove Causality A+ B+ B- D • Generalizability B- A- A- A • Feasibility C B A A RCT=Randomized, controlled trial; CS=Cohort study; CC=Case-control study; X-S=Cross-sectional study