Cardiovascular risk of oral contraceptives. Low, and mainly in women at risk

(1) The precise cardiovascular risk of oral contraceptives is poorly known because of a lack of reliable clinical studies and the numerous potential biases in epidemiological studies. (2) The absolute risk of coronary events is very low in women under 35 who are non smokers, have no history of coronary heart disease and have normal blood pressure. In women over 35, smoking over 10 cigarettes a day and arterial hypertension substantially increase the risk of coronary heart disease. (3) The absolute risk of stroke is low in young women who are not hypertensive and do not smoke. It is higher in the case of arterial hypertension. (4) The absolute risk of deep vein thrombosis is increased but remains moderate. Obesity, a family history of deep vein thrombosis, and hereditary clotting disorders are risk factors. (5) The cardiovascular risks linked to oral contraception seem to disappear after cessation. (6) The use of oral contraceptives with very low doses of oestrogen (less than 50 mug ethinylestradiol) reduces the associated risk of stroke. The risk of deep vein thrombosis is probably higher with combined contraceptives containing a third-generation progestagen (desogestrel or gestoden). (7) The coronary and cerebrovascular risks of progestagen-only contraceptives are poorly documented. Low-dose progestagen-only oral contraceptives have little effect on clotting factors or on carbohydrate and lipid metabolism. There may be a risk of deep vein thrombosis, however, with this type of contraceptive. (8) History, physical examination and simple laboratory tests before prescribing or renewing oral contraceptives are sufficient to detect the main contraindications, i.e. arterial hypertension, a history of coronary or cerebrovascular conditions, deep vein thrombosis, hypercholesterolaemia exceeding 3 g/l, hypertriglyceridaemia exceeding 3 g/l, unusually severe headache on a combined oral contraceptive and prolonged immobilisation. However, a combined oral contraceptive can be considered for some women with cardiovascular risk factors such as moderate hypercholesterolaemia or hypertriglyceridaemia, well-controlled insulin-dependent diabetes, uncomplicated cardiac valve disease, migraine not worsened by a combined oral contraceptive, varicose veins or a family history of deep vein thrombosis. (9) Pharmacists should be aware of these risk factors so that they can advise patients to see a doctor if new health problems arise between visits.