Hormonal Contraceptives Linkedin with Stroke and Myocardial Infarction :A Real-World, Nationwide, Prospective Cohort Study

Hormonal contraceptives have transformed family planning by placing women in charge of their reproductive lives. Despite huge benefits, however, some have raised concerns regarding cardiovascular risks, specifically thrombosis-related events, including stroke and myocardial infarction (MI). Evidence from a national prospective cohort study forms the basis of this paper, which examines how the use of modern hormonal contraceptives is associated with risk for these serious cardiovascular events.

Study Overview

In the present study, more than 1.6 million women between the ages of 15-49 years from Denmark were assessed for 14.3 million person-years of follow-up over the 1995-2009 time period. Scientists sought to determine the risk of MI and thrombotic stroke in users of different hormonal contraceptives and non-users. Having a large data set enabled researchers to control for confounding factors like age, education, and pre-existing health conditions.

Incidence of Thrombotic Events

Around 3,311 women had a first thrombotic stroke, and 1,725 had a first MI during the study. Case fatality was 1.0% for stroke and 10.8% for MI. Curiously enough, the risk of the events increased with age, and women aged 45-49 years had a 20-fold (stroke) and a 100-fold (MI) excess risk of the event compared with women aged 15-19 years.

Hormonal Contraception and Arterial Thrombosis

There was enough evidence based on research regarding the interaction of various forms of hormonal contraception and arterial thrombosis:

  • Combined Oral Contraceptives (COCs): COC users taking 30 to 40 µg of ethinyl estradiol experienced an enhancement of relative risk for thrombotic stroke and MI between 1.4 to 2.2 for stroke and 1.3 to 2.3 for MI based on the type of progestin employed. Surprisingly, the least risk was seen in products with norgestimate or cyproterone acetate, and the highest was seen in those with norethindrone or desogestrel.
  • Progestin-Only Contraceptives: The IUD-releasing levonorgestrel and subcutaneous implants, did not reveal an increased risk of thrombotic stroke or MI to any significant extent. This was an indication that progestin-only contraceptives may be safer in women with cardiovascular disease.
  • Non-Oral Combined Means: Risk of exposure to vaginal ring and contraceptive patch. In particular, contraceptive patches revealed a relative risk of 3.2 for thrombotic stroke, whereas vaginal rings provided a relative risk of 2.5. Such increased risks must be assessed with caution in issuing non-oral combined hormonal contraceptives.

Results of Other Studies Compared

Confirmatory evidence in the results of other studies concurs with the findings:

  • Swedish Cohort Study: A Swedish prospective cohort consisting of more than 48,000 women aged 30-49 years did not have an excess risk of MI in oral contraceptives and past users. The cohort was predominantly low-dose estrogen and second- or third-generation progestins, which indicates that products currently available are likely to be associated with a less adverse cardiovascular risk profile.
  • UK Cohort Study: UK studies showed a higher risk of ischemic stroke among users of oral contraceptives at the time of the study, with a relative risk of 2.9. A higher risk of MI was especially noted in heavy smokers who were users of oral contraceptives, as would be expected by the dual risks of smoking and hormonal contraceptive use.

Clinical Implications

Considering the relative increased risk for some hormonal contraceptives, it would be placed in context that the results:

  • Low Absolute Risk: Relative risks may be high while the absolute risk of thrombosis among the users of hormonal contraceptives remains low. For instance, the example given is 21.4 thrombotic strokes and 10.1 MIs per 100,000 person-years in users.
  • Risk Stratification: Other risk factors for women—i.e., advanced age, smoking, hypertension, or history of prior thrombotic events—must be offered close consultation by clinicians in balancing the risks and benefits of particular contraceptive modalities.
  • Alternative Options: In high-risk, progestin-only contraceptive methods, like the levonorgestrel-releasing intrauterine system, it may be a safer option without contributing to thrombotic risk.

Conclusion

The Danish national cohort study has useful comments regarding the cardiovascular risks of the current use of hormonal contraceptives. While some combined hormonal contraceptives have a modestly increased risk of thrombotic stroke and MI, the absolute risk is low. Contraception choice should be based on individual risk profile and preference, with the very important role of medical recommendation based on patient-specificity in family planning.

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