Women taking combined contraceptive pills containing the progestogen drospirenone have about three times the risk of venous thromboembolism (VTE) as women taking levonorgestrel-containing pills, shows UK general practice external published in the British Medical Journal.
Researchers examined data from the General Practice Research Database on VTE risk in women aged 15-44 years who were using a combined oral contraceptive pill. They compared 61 cases of VTE with 215 matched controls. The adjusted VTE risk in women currently taking pills containing the progestogen drospirenone was about three times the VTE risk in women taking levonorgestrel-containing pills.
A further study, published in the same issue of the BMJ, also looked at the relative risk of VTE in women taking drospirenone or levonorgestrel-containing combined pills, based on US claims data. These researchers found about twice the risk of non-fatal VTE in the drospirenone group compared with the levonorgestrel group, after adjustment for potential confounders.
The authors of both studies argue that increasing evidence that drospirenone-containing preparations are associated with a higher risk of venous thromboembolism than preparations containing levonorgestrel mean that more research, and a systematic review, are now needed.
The UK researchers conclude: “In the meantime, as no clear evidence exists to show that the use of the drospirenone pill confers benefits above those of other oral contraceptives in preventing pregnancy, treating acne, alleviating premenstrual syndrome, or avoiding weight gain, prescribing lower risk levonorgestrel preparations as the first line choice in women wishing to take an oral contraceptive would seem prudent.”