The study finds different cardiovascular risks associated with different hormonal contraceptives

The study finds different cardiovascular risks associated with different hormonal contraceptives

Certain hormonal contraceptives are linked to a higher risk of stroke and heart attack, a large study from Denmark finds The BMJToday, this relies on prescription records to provide more precise estimates for different products than previous studies.

The highest risk estimates were for estrogen-containing products, particularly the vaginal ring and skin patches.

The researchers emphasize that the absolute risk remains low, but given the widespread use of these products and the severity of these conditions, clinicians should consider these potential risks when prescribing them.

Almost 250 million women worldwide are estimated to use hormonal contraception. Previous studies have suggested a potential increased risk of ischemic stroke and heart attack with their use, but results have been inconsistent.

There is also a lack of evidence on the effects of different hormone combinations, how they are taken (e.g. pills, implants, injections, vaginal rings, or skin patches) and for how long.

To address this knowledge gap, researchers tracked national prescription records for more than two million Danish women aged 15 to 49 from 1996 to 2021 to find out whether use of contemporary hormonal contraceptives increased the risk of first-time ischemic stroke and heart attack compared to no use.

The different types of contraception they included were combined estrogen-progn pills, vaginal ring, patch, progestin-only pills, intrauterine devices, subcutaneous implant and intramuscular injections.

Women were excluded if they had a history of blood clots, cancer, liver disease, kidney disease, polycystic ovary syndrome, endometriosis or infertility treatment, used psychiatric medications, hormone therapy, or had a hysterectomy.

Cases of ischemic stroke and heart attack were recorded and other potentially influential factors such as age, education level and existing medical conditions such as high blood pressure and diabetes were taken into account.

The most commonly used hormonal contraceptive—the combined estrogen-progestin pill—was associated with twice the risk of ischemic stroke and heart attack, resulting in one additional stroke for every 4,760 women who use the combined pill for one year and one additional heart attack for every 10,000 women per year.

Progestin-only contraceptives, including pills and implants, presented a slightly increased risk, although they are lower than combined pills. Non-oral combination contraceptives such as vaginal ring and patch had a higher associated risk, with the vaginal ring increasing the risk of heart attack by 2.4 times and 3.8 times, while the patch increased the risk of ischemic stroke by 3.4 times.

The progestin-only intrauterine system was the only hormonal contraceptive not associated with increased risk, making this option safer for cardiovascular health. Length of use did not appear to influence risk.

This is an observational study, so no firm conclusions can be drawn about cause and effect, and the researchers cannot rule out that other unmeasured factors may have influenced their results.

However, this was a nationwide study with high-quality enrollment data that allowed for detailed tracking of hormonal contraceptive use, and the results were consistent upon further analysis, suggesting they are robust.

As such, they conclude: "Although the absolute risks were low, clinicians should consider the potential risk of arterial thrombosis when assessing the benefits and risks when prescribing hormonal contraception."

These diseases are rare, especially among young women, notes Therese Johansson at the Swedish Institute of Technology in a linked editorial. Still, these side effects are serious, and given its daily use by approximately 248 million women, the results have important implications.

She calls for educational campaigns to help women make informed decisions, as well as training for healthcare providers to ensure consistent and evidence-based advice.

Policymakers should also prioritize safer alternatives for women with cardiovascular risk factors that are both affordable and accessible, particularly in low-resource settings where cardiovascular risks are often underdiagnosed and untreated, she adds.

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