Combined pill risks quantified
Wednesday May 27th, 2015
The risk of venous thromboembolism may be more closely linked to new oral contraceptives than second generation pills, researchers warn today.
Oral contraceptives are used by about 9% of women of reproductive age around the world, and 28% in the UK.
The risk of dangerous blood clots is low - but significant numbers of women suffer them.
"Combined oral contraceptives form a substantial proportion of these," write Dr Yana Vinogradova, of Nottingham University, UK, and colleagues in The BMJ.
"Although combined oral contraceptives are generally effective in preventing pregnancy, they have measurable side effects such as venous thromboembolism," write the authors.
Previous studies have shown varying risks for different types of oral contraceptives (such as third generation pills compared with first or second generation pills), but such studies were done some years ago, and tended not to include new preparations containing drospirenone.
The team investigated the problem using figures on 10,562 cases of venous thromboembolism in women aged 15 to 49 years. Each was matched against five similar women who did not suffer the problem.
Women taking combined oral contraceptive faced nearly three times increased risk. The risks for desogestrel, gestodene, drospirenone and cyproterone were significantly higher than those for the second generation contraceptives levonorgestrel and norethisterone.
The highest numbers of extra cases of the illness were for desogestrel and cyproterone - approximately 14 extra cases a year per 10,000 women aged 15 to 49 years.
The experts conclude: "In these population based, case-control studies using two large primary care databases, risks of venous thromboembolism associated with combined oral contraceptives were, with the exception of norgestimate, higher for newer drug preparations than for second generation drugs."
The Royal College of GPs said the combined pill remained an "excellent choice" for women.
Dr Helen Stokes-Lampard, from the college, said: “When starting a woman on oral contraception, prescribers should remember that the second generation combined oral contraceptive pill is associated with a slightly lower risk of complications of thromboembolism than the newer, third generation pills.
“But this must be kept in perspective as the newer pills have some other advantages over second generation pills in terms of fewer side effects, so a decision specific to that patient’s needs and her previous experiences should be made."
Vinogradova, Y. et al. Use of combined oral contraceptives and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ 27 May 2015 doi: 10.1136/bmj.h2135 [abstract]
Tags: Pharmaceuticals | UK News | Women's Health & Gynaecology
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