Rare Stroke Risk Factor in Obese Women Taking Oral Contraceptives

Women who are obese and using oral contraceptives appear to have an increased risk for a rare type of stroke, a cerebral venous thrombosis or CVT, when compared to women of normal weight who do not use these drugs. These results were published in an article online by JAMA Neurology.

The Study

CVT is a rare condition which mainly happens in young adults and children. The risk factors for this rare stroke can overlap those of venous thromboembolism (VTE) and may include cancer and oral contraceptives. There are other risk factors for cerebral venous thrombosis including localized infections and head trauma. Whether or not obesity is associated as a risk factor for CVT has not been examined.

Dr. Jonathan Coutinho of the Academic Medical Centre, Amsterdam, the Netherlands, and other coauthors studied people with CVT from two different hospitals. The small research study of males and females included 186 case patients with CVT and 6,134 healthy control subjects for comparison. Patients with CVT were often younger (40 vs. 48 years old), female, more often used oral contraceptives and more frequently had a history of cancer when compared with control subjects.

The authors reported that obesity (a body mass index of 30 or higher) was associated with an increased risk of CVT and that the association was due to the increased risk in women who use oral contraceptives. There was almost a 30-fold increased risk of CVT among women with obesity taking oral contraceptives when compared to women of normal weight not taking oral contraceptives. There was also an increased risk of CVT in overweight women who use oral contraceptives.

However, there was no association between CVT and obesity in males or women who didn’t take oral contraceptives.

Limitations of the study included that only a small number of patients with CVT were included.

Conclusion to the Study

The authors concluded, “The increased risk of VTE and CVT associated with oral contraceptives in the presence of obesity might make physicians reluctant to prescribe oral contraceptives to obese women. However, although the relative risks are increased substantially, the absolute risks of CVT are smaller. Moreover, withholding oral contraceptives may lead to an increased number of unintended pregnancies and thus the number of pregnancy-related thrombosis cases. Nevertheless, obese women should be informed about the increased risk of thrombosis if they use oral contraceptives, especially if other risk factors are present. Alternative methods of contraception that are not associated with thrombosis, such as intrauterine device, might be offered to these women.”

In a related editorial written by Chirantan Banejee, MD, M.P.H. of the Medical University of South Carolina wrote, “The authors correctly point out that despite the manifold increase relative risk, the absolute risk of CVT in obese women taking OCs (oral contraceptives) still remains low and should not preclude OC use among them. Use of OCs has also been associated with an increased risk of arterial ischemic stroke in obese women. Better counseling and education of obese women informing them of the increased risk would be prudent, as would be consideration of alternate non-hormonal OC options.”