Retrospective Cohort Study - Define and steps

2. Retrospective Cohort Studies P E D 2012 2014 202 Historical / Non concurrent Cohort. . Both exposure & outcome home occured first me go back in time & take only exposure into Consideration then Coo le for development g some dls in both exposed & unexposed Example: effect I Jetal monitoring on neonatal deaths P 3. Combined Cohout Exposent 7: 2012 23/7 2020 2030 Mixed Cohort study R First me go back in time & take only enposure into convicteration lates cohorf is Jolloneed prospectively into Juture for outcome 2ND Steps 1 Selection g stuely subjects Uprant Gen popula . Expenal groups selected group Exposure grips. iii) 2 oblaing date on exposure D n+) d+s personal interview Remiew g records of - is Medual exam 1 Cest 001X IA ,I E mv. surveys show v1) 3. sell g comp. group . 4 M will 1. Int compainen P and STAY 0014 11. ext compainen and 4 Follow up Periodic medical exm Penodic home insit revelues SIST 3 lensons

5. Analyze 2x2 table Hacio DIS Pherent DIS absent alted elb exp a b Not exp. C 1) Incidence rate : among exposed 5 a/atb non export c/c+d barish ii) E stimation g annovation risk (strength g anociation) with a) Relative risk (RR) = Inc. g dls exp Inc I dls nonoxp. measures strength g amocration b/w cause & effect RR=1, RR>I, RR