Changes in prescription patterns of oral contraceptives in a northern Italian province: relation with venous thromboembolism

Effect of Age on Oral Contraceptive-Induced Venous Thrombosis

This study was undertaken to investigate the effect of age on oral contraceptive-induced venous thrombosis. All women seen in the University of Padua Department of Medical and Surgical Science who had had two courses of oral contraceptive therapy at different ages were included. A total of 28 subjects met these criteria. Fifteen patients had a congenital or acquired prothrombotic condition, whereas 13 women were normal subjects. The mean age at which thrombosis occurred was 33.3 and 36.3 years for women with or without a prothrombotic condition, respectively. The ages during which the women remained asymptomatic were 23.1 and 23.3 years for women with or without a predisposing defect, respectively. Thrombosis occurred, during the second course of oral contraceptive therapy, after the mean duration of 6.5 cycles or 18.4 cycles in women with or without prothrombotic defects, respectively. During the asymptomatic course, approximately the same number of women took old progestins or third-generation compounds. On the contrary, during the second period, 21 of 28 women took progestins with third-generation compounds. Age seems to plays an important role in oral contraceptive-induced venous thrombosis. In normal women, thrombosis occurred after a greater number of oral contraceptive cycles as compared with the women with prothrombotic defects. Because the majority of women took preparations that contained third-generation progestins during the second course of therapy, concomitant contributing effects of these compounds cannot be excluded.