3. Types of epidemiological studies

3.2 Analytic studies

Case-control studies

3.2.1 Observational studies

Example of a case-control study: oral contraceptives and the risk for thrombosis

Case report (19611): In one case, a young woman taking an oral contraceptive (birth control pills) was hospitalized for thrombosis.

Hypothesis: The use of oral contraceptives increases the mortality and the number of hospitalizations for thromboembolism.

Case-control study (19692) : The hypothesis was verified: the use of an oral contraceptive increases the risk of venous thrombosis. Additional studies confirmed this.

1Jordan WM. Pulmonary embolism. Lancet. 1961;1146-7.
2Sartwell PE, Masi AT, Arthes FG et al. Thromboembolism and oral contraceptives: an epidemiologic case-control study. Am J Epidemiol 1969;90:365-80. PubMed