Cerebral thrombosis and oral contraceptives. A case-control study.

To assess the influence of oral contraceptives (OC) on the risk of cerebral thrombosis and transient cerebral ischemic attacks, a 5-year case-control study including all Danish hospitals was conducted. All women 15-44 years old who suffered a cerebral thromboembolic attack (CTA) during the period 1994-95 and 1200 age matched control subjects were included. Of 309 patients and 1200 control subjects questionnaires sent out, 271 patients (87.7%) and 1074 control subjects (89.5%) responded and agreed to participate. After exclusion of women with nonvalid diagnoses, previous thromboembolic diseases, or current pregnancy, 219 patients and 1041 control subjects were available for analysis. After confounder control and with nonusers as reference, current users of first generation OC (50 micrograms of ethinyl estradiol [EE] or estrans) had an odds ratio (OR) of CTA of 1.86 (95% confidence interval [CI] 0.88-3.92); users of second generation OC (levonorgestrel or norgestimate) had an OR of 2.37 (1.35-4.16); and users of third generation OC (desogestrel or gestodene) had an OR of 1.32 (0.78-2.22). Users of OC with 50, 30-40, or 20 micrograms EE had OR of 2.65 (1.11-6.34), 1.60 (1.05-2.43), and 1.59 (0.57-4.58), respectively. Odds ratios for specific progestin types were as follows: estrans 1.37 (0.60-3.13), levonorgestrel 2.43 (1.40-4.21), norgestimate 7.09 (1.87-26.8), desogestrel 1.62 (0.72-3.63), and gestodene 1.24 (0.67-2.30). Duration of use was without significant influence on the risk and the OR were constant across the age bands. Compared with women who had never used OC, former users had an OR of CTA of 0.95 (0.66-1.51). In conclusion, use of OC with 50 micrograms of EE and OC with second generation progestins increased the risk of CTA significantly. OC with third generation progestins did not have any significant influence on the risk of CTA. The risk of CTA among former users of OC was not increased.