BACKGROUND: Previous epidemiologic studies of venous thromboembolism and oral contraceptive use are susceptible to bias in the detection of venous thromboembolic events. This case-control study uses a unique design to minimize the influence of detection bias. METHODS: Nonpredisposed women younger than the age of 40 years who underwent pulmonary angiography, lower extremity venography, or lower extremity duplex Doppler sonography at a large urban hospital were classified into a case group or control group based on results of their diagnostic studies. Medical records were reviewed for a history of current oral contraceptive use. RESULTS: Fifty-seven women met the study criteria during the 11-year study period. Seven of 9 women in the case group and 17 of 48 women in the control group were currently using oral contraceptives (odds ratio 6.38; 95 percent confidence limits 1.19, 34.2). CONCLUSIONS: The association previously noted between venous thromboembolism and oral contraceptive use is not due to bias in the detection of venous thromboembolic events.
BACKGROUND: Previous epidemiologic studies of venous thromboembolism and oral contraceptive use are susceptible to bias in the detection of venous thromboembolic events. This case-control study uses a unique design to minimize the influence of detection bias. METHODS: Nonpredisposed women younger than the age of 40 years who underwent pulmonary angiography, lower extremity venography, or lower extremity duplex Doppler sonography at a large urban hospital were classified into a case group or control group based on results of their diagnostic studies. Medical records were reviewed for a history of current oral contraceptive use. RESULTS: Fifty-seven women met the study criteria during the 11-year study period. Seven of 9 women in the case group and 17 of 48 women in the control group were currently using oral contraceptives (odds ratio 6.38; 95 percent confidence limits 1.19, 34.2). CONCLUSIONS: The association previously noted between venous thromboembolism and oral contraceptive use is not due to bias in the detection of venous thromboembolic events.
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Keywords:
Americas; Bias; Biology; Case Control Studies; Contraception; Contraceptive Methods--side effects; Developed Countries; Diseases; Embolism; Error Sources; Evaluation; Family Planning; Measurement; North America; Northern America; Oral Contraceptives, Combined--side effects; Oral Contraceptives--side effects; Research Methodology; Research Report; Risk Assessment; Risk Factors; Studies; Texas; Thromboembolism; United States; Vascular Diseases