Thrombotic diseases in young women and the influence of oral contraceptives

OBJECTIVE: In the evaluation of the clinical impact of thrombotic diseases in young women, age-specific incidence rates must be calculated for both arterial and venous thrombotic diseases, but also the case-fatality rate and figures for the clinical consequences among those who survive thrombosis must be included. The aim of this analysis was to quantify the clinical impacts of both arterial and venous thrombotic diseases among young, nonpregnant women and thereafter to assess the influences of oral contraceptives on these measures. STUDY DESIGN: Nationwide register data on the morbidity and mortality of venous thromboembolism, myocardial infarction, and thrombotic stroke in Denmark, 1980Denmark, -1993, and 3 ongoing case-control studies to assess the influence of oral contraceptives on the risk for development of these thrombotic diseases. RESULTS: In women 15-29 years old venous thromboembolism is about twice as common as arterial complications, whereas in women 30-44 years old the number of arterial complications exceeds that of venous diseases by about 50%. The mortality rate from arterial diseases is 3.5 times higher than that from venous diseases among women <30 years old and 8.5 times higher than that from venous diseases in women 30-44 years old. The proportion of women with a significant disability among women who had an arterial complication was about 30%; the proportion was about 5% among women with venous thromboembolism. CONCLUSION: Anticipating a differential influence on venous and arterial diseases from oral contraceptives with second-and third-generation progestogens, it was calculated that users of oral contraceptives with second-generation progestogens had 30% greater increased risk of thrombotic diseases, 260% greater increased risk of thrombotic deaths, and 220% greater increased risk of thrombotic disability than users of oral contraceptives with third-generation progestogens. (Am J Obstet Gynecol 1998;179:S62-7.) Key words: Cerebral thrombosis, disability, mortality, myocardial infarction, oral contraceptives, venous thromboembolism In the current discussion on oral contraceptives (OCs) and thrombotic diseases, much attention has been given to the relative risk estimates of thrombotic disease among current users of OCs compared with the risk among nonusers. This is, however, only a part of the necessary database that must be included to achieve a complete picture of the health impact of OCs on thrombotic diseases. The aims of this article are as follows: • To establish age-specific incidence and mortality rates of different thrombotic diseases in young women • To present relative risk estimates of development of different types of thrombotic diseases among users of different types of OCs derived from 3 ongoing Danish case-control studies on OCs and (1) cerebral thromboembolic attacks, (2) acute myocardial infarction, and (3) venous thromboembolism • To make a quantitative assessment of the impact of OCs on these 3 main thrombotic diseases in young women The scope is thus not to establish an overall risk-benefit calculation for OCs but only to quantify their impact on thrombotic diseases. In considering thrombotic diseases in young women, 3 diseases and 3 disease measures have clinical relevance. The 3 major thrombotic diseases that affect women are cerebral thromboembolic attack (including thrombotic strokes and transient ischemic attacks), acute myocardial infarction, and venous thromboembolism (including deep venous thrombosis and pulmonary embolism). Initially, it is important to realize that venous and arterial diseases have quite different etiologies, clinical manifestations, clinical consequences, and treatments. It is therefore not unlikely that sex hormones have differential effects on the venous and the arterial circulations. The clinical impact of a thrombotic disease is deter