By Nadia Arshad, PhD in TREC
A study published in British Medical Journal on the 26th of May 2015 have looked at the association between usage of oral contraceptives, and the risk of developing blood clots, also called venous thromboembolism (VTE), in a large registry-based study conducted in the United Kingdom in 2001-2013.
There is much evidence on the usage of oral contraceptives and the risk of VTE. However, this study used the two largest databases in the United Kingdom (QResearch and Clinical Practice Research Datalink) and investigated the risk of VTE with the use of newer combination oral contraceptives (estrogen and progestin hormones) in women aged 15-49 years.
The researchers gathered 10,562 cases of first-time VTE and 42,034 controls without VTE using both databases and collected information regarding the usage of oral contraceptives in the previous year through their prescription information. 48% of the women had at least one prescription of combined oral contraceptives throughout the study period, and that levonorgestrel was the most commonly prescribed compound.
The results from the study indicates that current use of any combined oral contraceptive is associated with 3 times increased risk of VTE. Current users of new oral contraceptives (except norgestimate) has 4 times higher risk of VTE, whereas levonorgestrel, norethisterone and norgestimate users has 2.5 times increased risk of VTE as compared to non-users.
The study concludes that the risk of VTE associated with combined oral contraceptives is higher for newer (3rd and 4th generation) drug preparations (such as desogestrel, gestodene, drospirenon, cyproterone) than for 2nd generation oral contraceptives (such as levonorgestrel and norethisterone).
References: Vinogradova Y, Coupland C & Hippisley-Cox J. Use of combined oral contraceptives and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ 2015; 350:h2135.