Oral contraceptives and thromboembolic disease.

Abstract

The writer comments on a recent article by Dr. M.P. Vessey and Dr. R. Doll in which oral contraceptives and thromboembolic disease are discussed. Drs. Vessey and Doll noted that 42% of the women who developed thromboembolic disease had been using oral contraceptives for less than 6 months. Yet they later remarked that there is no suggestion in the study that venous thromboembolism tends to occur shortly after beginning the use of oral contraceptives. The writer of this letter states that anything less than 6 months is a fairly short time in the context of this form of drug therapy and that 42% is not an inconsiderable proportion. He comments that he has been struck by the frequency with which the cases of thromboembolic disease have occurred within a few months of the patients having started a course of oral contraceptives. He believes it is important to know if there is a critical period of a few months after which the incidence of thromboembolism falls abruptly or if the risk remains at the same level throughout the period of taking the pill. He would welcome Drs. Vessey and Dolls comments on this point.