The association between oral contraceptives and stroke has long been known. The guidelines released by the AHA is an attempt to synthesize the various studies.
The guidelines state that the risk from low-dose oral contraceptives (OCs) is small, perhaps 1.4 -2.0. This is lower than the risk of stroke from pregnancy.
OCs: Summary and Gaps
The relative increase in stroke risk with low-dose OCs is small, approximately 1.4 to 2.0 times that of non-OC users. [sup]144[/sup] On the basis of the longitudinal data from the Danish population-based study, among 10000 women who use the 20-μg dose of desogestrel with ethinyl estradiol for 1 year, 2 women will have arterial thrombosis and 6.8 will have venous thrombosis. [sup]144[/sup] The risk of stroke with OC use also appears to belower than the risk associated with pregnancy (≈3 per 10000 deliveries.) [sup]143[/sup]
Despite the overall low risk of stroke from hormonal contraception, certain subgroups of women, particularly those who are older, smoke cigarettes, or have hypertension, diabetes mellitus, obesity, hypercholesterolemia, or prothrombotic mutations, may be at higher risk for stroke. Estimates are based primarily on case-control studies and a smaller number of cohort studies primarily from northern European countries, which limits generalizability to other populations.
(see page 16)
- OCs may be harmful in women with additional risk factors (eg, cigarette smoking, prior thromboembolic events) (Class III; Level of Evidence B) [sup]224,225[/sup]
- Among OC users, aggressive therapy of stroke risk factors may be reasonable (Class IIb; Level of Evidence C) [sup]224,225,231[/sup]
- Routine screening for prothrombotic mutations before initiation of hormonal contraception is not useful (Class III; Level of Evidence A) [sup]229[/sup]
- Measurement of BP before initiation of hormonal contraception is recommended (Class I; Level of Evidence B) [sup]220,235,236[/sup]
(see page 17)