Takaisin Tulosta

Oral contraceptives in patients who have experienced one venous thrombosis

Evidence summaries
Editors
Last reviewed as up-to-date 12.11.2020Latest change 12.11.2020

Level of evidence: C

The risk of a recurrent venous thromboembolism after one thrombotic event in users of oral contraceptives may be increased compared with nonusers.

A systematic review «Koster T, Small RA, Rosendaal FR, Helmerhorst FM. ...»1 including 8 case-control studies, 6 follow-up studies and one randomised trial was abstracted in DARE. The unweighted summary relative risk for a new venous thrombosis or thromboembolism (VTE) was 2.9 (95% CI 0.5 to 17)(G test for homogeneity p<0.001). For case-control studies the RR was 4.2 (95% CI 1.3 to 14), and for follow-up studies it was 2.1 (95% CI 0.3 to 16). For the one RCT it was 1.1 (95% CI 0.4 to 2.9). The funnel plot did not reveal evidence of publication bias.

In a prospective cohort study «Le Moigne E, Delluc A, Tromeur C et al. Risk of re...»2 in France the risk of a recurrent VTE in women after a first oestrogen contraception associated VTE episode was assessed. Women under 50 years were consecutively enrolled between 1992 and 2011. Of the 241 women who were followed-up after stopping anticoagulation, there were 180 COC-users and 61 non-users. Median duration of follow-up off-anticoagulants was 66 months (interquartile range: 33-103). There were 14 recurrences in COC-users and 5 cases in non-users. No significant association was found between exposure to COC and the incidence of recurrent VTE after adjustment for age or after restricting the analysis to major unprovoked VTE: incidence rate of recurrence 17.9/1,000/year (95% CI: 9.6-33.2) in women with COC as compared with 17.6/1,000/year (95% CI: 6.6-47) with an incidence ratio of 0.7 (95% CI: 0.2-2.4, p=0.59).

A meta-analysis «...»3 assessed the thrombosis risk in thrombophilic COC-users. 12 case-control and 3 cohort studies were included. A distinction was made between 'mild' (factor V Leiden and prothrombin-G20210A mutation) and 'severe' thrombophilia (antithrombin deficiency, protein C deficiency, protein S deficiency, double heterozygosity or homozygosity of factor V Leiden and prothrombin-G20210A mutation). In COC-users, mild thrombophilia increased the risk of VTE almost 6-fold (rate ratio [RR], 5.89; 95%CI 4.21 to 8.23) and severe 7-fold (RR, 7.15; 95% CI, 2.93 to 17.45). The cohort studies showed that absolute VTE risk was far higher in COC-users with severe thrombophilia than in those with mild thrombophilia (4.3 to 4.6 vs. 0.49 to 2.0 per 100 pill-years, respectively), and these differences in absolute risks were also noted in non-affected women (0.48 to 0.7 vs. 0.19 to 0.0), but with the caveat that absolute risks were estimated in relatives of thrombophilic patients with VTE (i.e. with a positive family history). The investigators concluded that the additive VTE risk of mild thrombophilia is modest.

References

  1. Koster T, Small RA, Rosendaal FR, Helmerhorst FM. Oral contraceptives and venous thromboembolism: a quantitative discussion of the uncertainties. J Intern Med 1995 Jul;238(1):31-7. «PMID: 7608644»PubMed «DARE-11995001917»DARE
  2. Le Moigne E, Delluc A, Tromeur C et al. Risk of recurrent venous thromboembolism among young women after a first event while exposed to combined oral contraception versus not exposed to: a cohort study. Thromb Res 2013;132(1):51-5. «PMID: 23786893»PubMed
  3. van Vlijmen EF, Wiewel-Verschueren S, Monster TB et al. Combined oral contraceptives, thrombophilia and the risk of venous thromboembolism: a systematic review and meta-analysis. J Thromb Haemost 2016;14(7):1393-403. «PMID: 27121914»PubMed