These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Oral contraceptives and venous thromboembolism: a case-control study designed to minimize detection bias.
    Author: Realini JP, Encarnacion CE, Chintapalli KN, Rees CR.
    Journal: J Am Board Fam Pract; 1997; 10(5):315-21. PubMed ID: 9297655.
    Abstract:
    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. Both case-control and cohort studies have consistently documented an association between oral contraceptive (OC) use and venous thromboembolism risk. However, since OC users undergo closer medical surveillance than non-users, these studies are susceptible to detection bias. To overcome this potential source of bias, the present study used a new case-control study design in which 234 women under 40 years of age with suspected deep vein thrombosis or pulmonary embolism recruited from University Hospital in San Antonio, Texas, during 1983-94 underwent contrast venography, pulmonary angiography, or duplex Doppler ultrasound examination. 127 of these women were subsequently excluded from the study because of predispositions to venous thromboembolism. The 9 women whose test results were positive comprised the case group, while the 48 with negative findings served as controls. 7 of the 9 cases and 17 of the 48 controls were current OC users (odds ratio, 6.38; 95% confidence interval, 1.19-34.2). Although documentation of the OC brands women were using was sparse, 12 of the 13 women for whom these data were available were using OCs containing 35 mcg or less of estrogen. The findings of this analysis indicate that the documented association between OC use and venous thromboembolism is not a result of detection bias. The use of women undergoing diagnostic procedures to form both the case and control groups should be replicated in larger populations and diverse settings. The study design could be further strengthened by collecting data on OC use prospectively and uniformly, before women undergo diagnostic procedures.
    [Abstract] [Full Text] [Related] [New Search]