tokens: An analysis for factor V Leiden and the G20210A mutation in the prothrombin gene was conducted in 217 patients and 763 controls RESULTS : The odds ratio for myocardial infarction among women who used any type of combined oral contraceptive , as compared with nonusers , was 2 . 0 ( 95 percent confidence interval , 1 . 5 to 2 . 8 ) .