[Oral contraceptives and cerebral thromboembolism. A Danish case-control study]

A retrospective case control study was carried out in order to assess the risk of developing cerebral thromboembolism by use of low dose oral contraceptives (OC). The subjects were all the 794 women in Denmark aged 15-44 who had suffered a cerebral thromboembolic attack (CTA) during the period 1985-1989, and an age-matched randomly selected control population of 1588 women. CTA included occlusion of precerebral arteria (ICD 432), cerebral thrombosis (ICD 433), cerebral embolism (ICD 434), transitory cerebral ischaemia (TCI; ICD 435) and the unspecified group apoplexia cerebri (ICD 436). Of 692/1584 case/control questionnaires sent out, 590/1396 (85.1/88.1%) were returned. Among the cases, 15 refused to participate, 69 had a revised or unreliable diagnosis, 40 had previously had thromboembolic disease, 13 were pregnant, and 152 had a disease predisposing them for CTA, leaving 323 without known predisposition, of whom 320 reported use/non-use of OC. Among 1396 controls, eight either refused to participate, were mentally retarded or resident in foreign countries; 18 returned an uncompleted questionnaire, 17 had previously had thromboembolic disease, 31 were pregnant, and 130 had a disease predisposing them to CTA. Thus, 1198 non-predisposed controls were provided, among whom 1197 reported use/non-use of OC. Among 320 cases, 116 (36.3%) were OC users at the time of the CTA, vs. 191 users (16.0%) among 1197 controls, corresponding to a crude odds ratio (OR) of 3.00.(ABSTRACT TRUNCATED AT 250 WORDS)