Risk of VTE among users of oral contraceptives.

摘要

We have recently reviewed two studies, a cohort study conducted in Denmark, and a case-control study conducted in The Netherlands, in which it was claimed that the risk of venous thromboembolism (VTE) among users of oral contraceptives (OCs) containing desogestrel, gestodene, drospirenone and cyproterone is greater than among users of levonorgestrel-containing OCs. We concluded that in both studies the comparisons among the progestogens were not valid due to methodological limitations. The Danish study linked prescription data recorded in one national registry to hospital discharge diagnoses of VTE recorded in another registry. The investigators stated that in an earlier validation study 10% of the diagnoses documented between 1994 and 1998 "were uncertain". In the study under review they acknowledged that they relied on the "final discharge diagnoses as reported", and that they were unable to "evaluate the validity of each included diagnosis of [VTE]".