![]() Loss to follow-up: When multiple outcomes or specific disease incidence is the outcome of interest, bias can be a serious problemģ. Tend to be expensive (large sample size) and time consuming (long follow-up period)Ģ. Minimizes recall bias Disadvantages of Cohort Studiesġ. Allows for calculation of incidence of diseases in exposed and unexposed individualsĥ. Temporality: Exposure precedes outcome because the cohort is disease free at baselineģ. Study to determine if the Russian Salad was the cause of a food borne illness outbreak Advantages of Cohort Studiesġ.Study to determine if children who receive influenza vaccination miss fewer days of school.Study to determine if smokers have a higher risk of lung cancer.RR is the measure used with cohort studies Cohort Study Examples The relative risk is the risk of disease in the exposed group divided by the risk of disease in the non-exposed group. ![]() It is the “ratio of incidence of disease among exposed to incidence of disease among non- exposed” They assesses exposure at “baseline” and disease status at “follow-up”.Ģ x 2 table is used to summarize counts of disease and exposure in order to perform calculations of association.Ī = number who are exposed and have the outcomeī = number who are exposed and do not have the outcomeĬ = number who are not exposed and have the outcomeĭ = number who are not exposed and do not have the outcomeĪ + c = total number who have the outcomeī + d = total number who do not have the outcomeĪ + b + c + d = total study population Relative Risk (RR) Cohort studies are longitudinal, prospective studies, forward looking studies or incidence studies. ![]() people put into groups based on certain shared traits-there is an inherent lack of randomization.Cohort is an ancient Roman military unit of 300-600 men, a group of soldiers marching forward in battle.
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