[Hormonal contraception and thromboembolic disease--new epidemiologic data].

OBJECTIVE

To sum up the results of studies published between 1996 and 2000 on the venous thromboembolism (VTE) risk at combined oral contraceptives users.

DESIGN

Review of literature.

SETTING

1st Department of Obstetrics and Gynecology, Masaryk University, Brno, Czech Republic.

METHODS

Summary of the results of substantial studies published on this topic. Studies were identified by Medline database search.

RESULTS

Four important epidemiological studies published at 1995 and 1996 (WHO, Spitzer et al., Jick et al., Bloemenkamp et al.) demonstrated two fold increased risk of VTE at users of third generation OCs in comparison with second generation OCs. Publication of these studies was followed by critic based on their possible methodological weaknesses (prescribing bias, "healthy user" effect, refferal bias etc.). Other epidemiologists confirmed results of these studies and excluded the possibility of systematic biases. Pathophysiological mechanisms that could explain the different risks were also found. Jick's analysis of GRPD published in 2000 also confirmed the results from 1995 and 1996.

CONCLUSION

The different risk of VTE at users of oral contraceptives with different progestins probably exists. However, the relative risks of VTE demonstrated in recent studies are low.