Ischaemic stroke and combined oral contraceptives: results of an international, multicentre, case-control study

Background The association between use of oral contraceptives (OCs) and cerebral infarction was established in studies from northern Europe and the USA during the 1960s and 1970s. Since then, the constituents of hormonal OCs have changed and now contain lower doses of oestrogen and progestagen. Current recommendations restrict OC use to younger women who do not have other risk factors for cardiovascular disease, in this international study we assessed the risk of CC-associated first stroke in women from Europe and other countries throughout Vie world.Methods In this hospital-based, case-control study, we assessed the risk of ischaemic stroke in association with current use of combined OCs in 697 cases, aged 20-44 years, and 1962 age-matched hospital controls in 21 centres in Africa, Asia, Europe, and Latin America. The diagnosis of ischaemic stroke was almost exclusively based on computed tomography (CT), magnetic resonance imaging (MRI), or cerebral angiography carried out within 3 weeks of the clinical event. Ail cases and controls were interviewed while in hospital with the same questionnaire, which included information on medical and personal history, details of lifetime contraceptive use, and blood-pressure measurements before the most recent episode of OC use.Findings The overall odds ratio of ischaemic stroke was 2 . 99 (95% CI 1 . 65-5 . 40) in Europe and 2 . 93 (2 . 15-4 . 00) in the non-European (developing) countries, Odds ratios were lower in younger women and those who did not smoke, and less than 2 in women who did not have hypertension and who reported that their blood pressure had been checked before the current episode of OC use. By contrast, among current OC users with a history of hypertension, the odds ratio was 10 . 7 (2 . 04-56 . 6) in Europe and 14 . 5 (5 . 36-39 . 0) in the developing countries. In Europe, the odds ratio associated with current use of low-dose OCs (