Cohort Study - Definition, Prospective cohort study and Advantages and Disadvantages of Retrospective Cohort Study

Cohort Study spotinonsA bequest Cohort - group Cohorte are Identified pnior to appearance of the dls is ie : they are Nwong dls study groups are observed over a period g lime (Jollow up) . study proceeds Jonward ( cause Co effect) Time Dirn g enaming Narma D/S Exposed No dls Population PPI. cout dls towmer pls Notexp No Dls. P.riospective study - time formand Magor Longitudinal study - deprided patient Incideme study - c time new career. write Forward looking Study wayag would Cause to effect Exp. to outcome Rf to dls. /ortna) sea) Follow- up. study 211. which i) Types cont EXP dls 1. Prospective Cohorle study 2020 2010 286 - Current cohart Study / Concurrent cohouf study wints Outcome has not yet occured. when the study has is begun, has occured Look for dev. g dls in both exposed & non enposed groups en out structions (NO Eg Frahming harm heart study were \ precerving royer > Hos 3 ww Merative 1.0

Advantage CANDS because this ment relations Incidance & RR calculation Natural history g dls. Done for rare cames. Useful for chr. dls.

Testing multiple effects measures time reln ' No recall bias their bill Disadvantage Not Jan rane dls. Prospective - Example expensive time communing Frahmingham heart study Loss to Jollowsup Example - Retro whort Researches identifies a cohost g individuals who shane common exposure. ie workers is coal mine smoking hot Then enamines past records g individuals (smokers 4 non smokers) to understand the effect g smoking on development I cunt outcome ie lung concerning Begins St only c part records is exposure a indiv to find possible link b/w exp to Rf & the present outcome altristrars stock Researcher Invoice instrust walan Researcher veid First studies yet First studies evt Case control Exposed Non exp (c dls) (Eoutdlis) 10.12 Compans Comp loasta ingon "Luyog Exposure. case contnd Outcome. Reins- which