September 10, 2012 | Elena Perez
In June, researchers at the University of Copenhagen published the largest cohort study of hormonal contraceptives and their association with heart attacks and strokes. The study followed more than 1.6 million Danish women, ages 15 to 49, for a 15-year period between 1995 and 2009, allowing researchers to observe more than 14 million person-years, or the total number of years that oral contraceptives were used during this study.
The findings are worth mentioning.
Risk of Heart Attack and Thrombotic Stroke
Though researchers stated the risk of myocardial infarction (heart attack) and thrombotic stroke (stroke from blood clotting) was quite low, the study still showed a link between the two. Overall, 21 strokes and 10 heart attacks occurred for every 100,000 person-years of study.
The Type of Hormone Can Increase Risk
Women who took oral contraceptives with 20 micrograms of ethinyl estradiol increased their risk of heart attack by a factor of 1.7. Using 30 to 40 micrograms of ethinyl estradiol increased strokes by a factor of 1.3 and heart attacks by a factor of 2.3. The type of progestin, however, only changed the risk slightly, according to researchers.
Since the type of hormones used in oral contraceptives can increase the risk of heart attack or thrombotic stroke, women should ask their doctors about the dosage and types of hormones in their oral contraceptives and why the brand was chosen for them. It is important for women to question the prescriptions they are given, because FDA regulations may not be sufficient.
Yasmin is an example of a hormonal contraceptive that uses ethinyl estradiol. AdverseEvents.com has 16,546 adverse reports listed for Yasmin. Of these, 9,847 of the reports suspect that Yasmin is the primary reason for various illnesses, such as pulmonary embolism (blockage of the main artery of the lung), and deep vein thrombosis (blood clot in a deep vein).
In May of 2011, the FDA reported that studies show women using oral contraceptives with drospirenone are two to three times more likely to suffer from venous thromboembolism events (VTE), or blood clotting in the veins. The FDA stated it would evaluate results, but oral contraceptives that contain drospirenone, such as Yasmin, are still on the market.
Understanding the quantity and the type of hormones that are linked to adverse effects can help women determine which oral contraceptives are best for them. Bear in mind that a woman’s choice in oral contraceptives may change over time, depending on factors such as age.
Age Increases Risk of Heart Attack and Thrombotic Stroke
Women using oral contraceptives in the oldest age group, age 45 to 49, were found to have a higher risk of heart attack and thrombotic stroke than women in the youngest age group, between 15 and 19 years of age. The risk of thrombotic stroke increased by a factor of 20, while the risk of heart attack increased by a factor of 100 for women between the ages of 45 and 49.
The researchers felt this information was particularly important, since the risk of blood clotting and heart attack outweigh the risks of pregnancy. Risk of arterial thrombosis, or clotting of the arteries, increases after the age of 30, so women using oral contraceptives should be aware of the increased incidence of heart attack and stroke as they age, and may want to consider alternative forms of birth control.
Correlation Between Level of Education and Risk
The study also found that women with the highest level of education were less likely to have thrombotic strokes and heart attacks. In fact, educated women had half as many thrombotic strokes and only a third of the heart attacks as women with the lowest level of education.
There are a number of reasons that may account for why women with the highest level of education have a lower level of heart attacks and thrombotic stroke.
A study published in the International Journal of Epidemiology found that one’s socioeconomic status, which takes into consideration education and occupation, does affect diet and nutrition. If women with the highest level of education are more likely to eat healthy meals and minimize consumption of fried food, their diet could be the reason for the reduced the risk of heart attack and stroke.
It is also likely that women with higher levels of education exercise more, thereby improving their heart conditions. Women with higher educations may be more aware that exercise can help maintain good health. It is also possible that women with lower levels of education have longer work hours and less time to exercise, which could negatively impact coronary health.
In addition to diet and exercise, women with higher levels of education may be more likely to stay abreast of news and current events that highlight which habits are considered healthy (like meditation) or harmful (like smoking), which pharmaceutical drugs are being evaluated (like Yasmin), and who can be trusted to provide unbiased information (question everything).
Share the Knowledge
One of the main researchers, Dr. Lidegaard, received grant support from Bayer Pharma, while lecture fees and travel reimbursements were paid by Bayer Denmark. He also provided testimony in a US legal case involving oral contraceptives and venous thromboembolism. Bayer happens to be the pharmaceutical company that makes Yasmin, the oral contraception reported on AdverseEvents.com.
The other main researcher, Dr. Løkkegaard, received travel reimbursement from Pfizer, a pharmaceutical company that manufactures Lybrel, an oral contraceptive with 20 micrograms of ethinyl estradiol. The Material Safety Data Sheet for Lybrel acknowledges its association with myocardial infarction, strokes, and blood clotting of the veins.
Women who recognize that a conflict of interest may produce biased results may wonder how low the risk of myocardial infarction and thrombotic stroke really is. It’s important to ask questions. It’s important to share knowledge. One way to educate women is by spreading the word.