A MULTINATIONAL CASE-CONTROL STUDY OF CARDIOVASCULAR-DISEASE AND STEROID-HORMONE CONTRACEPTIVES - DESCRIPTION AND VALIDATION OF METHODS

A hospital-based, case-control study of the association between curren t usage of oral contraceptives and first-time cases of acute myocardia l infarction, stroke, or a venous thromboembolic event (deep vein thro mbosis or pulmonary embolus) was carried out in 17 countries from four regions (Africa, Asia, Europe, and Latin America). A total of 3792 ca ses and 10,281 hospitalised controls matched for age were recruited du ring a 4-year period, ending in June 1993. The study was designed to h ave sufficient power to detect a relative risk of 2 for developing eac h of the three study diseases, associated with current oral contracept ive use in each of the four regions, with the exception of acute myoca rdial infarction (for which all non-European regions were to be combin ed) and for venous thromboembolic events in Asia, where these disorder s are rare. This report describes the background, pilot study, methods , and the analyses carried out to validate the methods used in the stu dy.