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Ischemic stroke risk with oral contraceptives: A meta-analysis
L A Gillum1, S K Mamidipudi, S C Johnston
1Department of Neurology, Box 0114, University of California, San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0114, USA.
JAMA
|June 29, 2000
Summary
Current oral contraceptive (OC) use is linked to a higher risk of ischemic stroke, even with lower estrogen doses. However, the absolute risk increase for stroke remains small in women using OCs.
Area of Science:
- Neurology
- Cardiovascular Health
- Pharmacology
Background:
- The association between oral contraceptive (OC) use and ischemic stroke has been debated for decades.
- Despite extensive research, a definitive consensus on the increased risk of stroke in OC users remains elusive.
Purpose of the Study:
- To systematically review and synthesize existing literature to ascertain if OC use is associated with an elevated risk of ischemic stroke.
- To quantify the risk of ischemic stroke associated with oral contraceptive use.
Main Methods:
- A comprehensive literature search was conducted across multiple databases (MEDLINE, BIOSIS, etc.) for studies published between January 1960 and November 1999.
- Seventy-three studies on ischemic stroke risk and OC use were identified, with 16 meeting strict inclusion criteria for meta-analysis, including adequate sample size and control for confounding factors.
- Data extraction and risk assessment were performed independently by two investigators, with disagreements resolved through discussion.
Main Results:
- Meta-analysis of 16 studies revealed a significantly increased risk of ischemic stroke associated with current OC use (RR, 2.75).
- Risk was elevated across all estrogen dosages, though lower estrogen doses showed a trend towards reduced risk (P=.01).
- Population-based studies controlling for smoking and hypertension reported a summary RR of 1.93 for low-estrogen OCs, translating to a small absolute increase in stroke incidence.
Conclusions:
- Current oral contraceptive use is associated with an increased risk of ischemic stroke, irrespective of estrogen dosage.
- While the relative risk is elevated, the absolute increase in stroke risk among OC users is minimal due to the low incidence of stroke in this demographic.
- The findings underscore the importance of considering individual risk factors and the type of OC preparation when assessing stroke risk.
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