POPM 3240 Lecture 18: Cross sectional studies
24 Feb 2019
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Cannot make any conclusions about an association between exposure and outcome. Main types are; case reports, case series and surveys. Compares between groups to explore associations between exposure and outcome. Observing natural occurrences and drawing conclusions based on these observations. Analytical observational studies (differ based on selection of study subjects) Cross-sectional: subjects are selected without regard to exposure or outcome. Usually point in time and prevalence cases. Cohort: subjects are selected based on exposure and followed over time to determine if they develop the disease of interest. Case-control: subjects are selected based on disease status and exposure status is compared between diseased and not diseased. Usually retrospective and may be incidence or prevalence cases. Complete control over allocation of subjects we intervene. Objective: is the exposure related to the outcome (disease status?) Analysis: compare prevalence of disease in exposed and unexposed. Can determine prevalence of exposure and outcome in the population.
