Risk of a rare type of stroke known as cerebral venous thrombosis (CVT) appears to be increased in obese women who use oral contraceptives compared to women of healthier weight who did not take oral contraceptives, according to an article published online in the journal JAMA Neurology.
Risk factors for CVT seem to overlap some of those linked to venous thromboembolism (VTE), including oral contraceptives and cancer. Other risk factors specifically related to CVT include head trauma and local infections; obesity has not been assessed as a risk factor for CVT.
The study, “Risk of Cerebral Venous Thrombosis in Obese Women,” was co-authored by Jonathan M. Coutinho, M.D., Ph.D., a researcher at the Academic Medical Center in Amsterdam.
Coutinho and his colleagues studied patients with CVT from two different hospitals, including 186 men and women, and 6,134 healthy controls for comparison purposes – the study acknowledged that the limited number of CVT patients might be a limitation. Patients with CVT were women; generally younger when compared to the control group (average age of 40 compared to 48 in the control group); more often taking oral contraceptives; and with more reports of cancer history.
The authors found that obesity in women, determined by a body mass index (BMI) of 30 or higher, is linked with a 30-times increased risk of stroke when added to oral contraceptives intake, compared to normal-weighted women who did not use oral contraceptives. There was no correlation between obesity and CVT in men or women who did not take oral contraceptives.
“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 small. Moreover, withholding oral contraceptives may lead to an increase in unintended pregnancies, and thus the number of pregnancy-related thrombosis cases,” the authors wrote in a press release.
“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,” the authors wrote.