Overview

A recent comprehensive study conducted in Denmark has highlighted significant associations between certain hormonal contraceptives and elevated risks of ischemic stroke and heart attack. Published in The BMJ, this research utilizes extensive prescription records to provide clearer estimates of risk linked to various hormonal contraceptive methods.

Findings on Risk Levels

The analysis indicates that estrogen-containing contraceptives, particularly the vaginal ring and skin patch, pose the highest risk. While the overall risk remains relatively low, the researchers emphasize the importance of considering these risks during the prescription process, especially given the widespread use of hormonal contraceptives by an estimated 250 million women globally.

Context of the Study

Prior studies have suggested a potential increase in the risk of ischemic stroke and heart attacks associated with hormonal contraceptive use; however, results have been inconsistent. This study aims to close the knowledge gap regarding the effects of different hormone combinations and delivery methods, including pills, implants, injections, and patches.

Methodology

The researchers meticulously tracked national prescription data for over two million Danish women aged 15 to 49 from 1996 to 2021. They aimed to determine whether the use of hormonal contraceptives heightened the risk of experiencing a first-time ischemic stroke or heart attack compared to women who did not use these methods. The study assessed various contraceptive types, including combined estrogen-progestin pills, vaginal rings, patches, progestin-only pills, intrauterine devices, subcutaneous implants, and intramuscular injections.

Participant Exclusions

Women with pre-existing conditions such as blood clots, cancer, liver disease, kidney disease, polycystic ovary syndrome, endometriosis, infertility treatments, those using psychiatric medications, hormone therapy, or who had undergone hysterectomy were excluded from the study. The researchers documented cases of ischemic stroke and heart attack while controlling for factors like age, educational background, and existing health conditions such as hypertension and diabetes.

Risk Assessment

The findings revealed that the commonly used combined estrogen-progestin pill was associated with a twofold increase in the risk of ischemic stroke and heart attack. Specifically, this translates to an additional stroke occurring for roughly every 4,760 women on the combined pill for one year, and one extra heart attack for every 10,000 women using it annually. Progestin-only contraceptives, while also presenting a slight increase in risk, were found to be less risky than the combined pills.

Moreover, non-oral combined contraceptives such as the vaginal ring and patch exhibited notably higher risks, with the vaginal ring linked to a 2.4-fold increase in ischemic stroke risk and a 3.8-fold increase in heart attack risk. The patch was associated with a 3.4-fold increase in the risk of ischemic stroke. Conversely, the progestin-only intrauterine system emerged as the only hormonal contraceptive not correlated with heightened cardiovascular risks, suggesting it as a safer option for women concerned about such effects.

Implications of the Study

Although this observational study cannot definitively establish causation, the researchers assert that the substantial dataset and consistent results lend credibility to their findings. They recommend that healthcare providers weigh the potential risk of arterial thrombosis when discussing the benefits and drawbacks of hormonal contraceptive options with patients.

Despite these risks being relatively rare, especially among younger women, the implications of the study are profound given the number of women using hormonal contraceptives worldwide. Experts advocate for educational initiatives to empower women in making informed decisions regarding contraceptive options and call for healthcare providers to receive comprehensive training for evidence-based counseling.

Additionally, policymakers are urged to prioritize the availability and affordability of safer alternatives for women with cardiovascular risk factors, particularly in low-resource settings where such risks may often remain undiagnosed and untreated.

Further Reading

For more detailed insights, refer to the publication: Stroke and myocardial infarction with contemporary hormonal contraception: real-world, nationwide, prospective cohort study, available in The BMJ.