THROMBOEMBOLISM AND ORAL CONTRACEPTIVES - AN EPIDEMIOLOGIC CASE-CONTROL STUDY

Sartwell, P. E (Johns Hopkins Univ. School of Hygiene and Public Health, Baltimore, Md. 21205), A. T. Masi, F. G. Arthes, G. R. Greene and H. E. Smith. Thrombo-emboIism and oral contraceptives: An epidemiologic case-control study. Amer. J. Epid., 1969, 90: 365-380.-A retrospective study of thromboembolism in females of reproductive age was conducted in five American cities. Cases were 175 women aged 15-44, discharged alive from 43 hospitals after initial attacks of idiopathic thrombophlebitis, pulmonary embolism, or cerebral thrombosis or embolism. Idiopathic cases constituted only a small fraction of total thromboembolism patients. The 175 hospital controls were matched pairwise with the cases on hospital, residence, time of hospitalization, race, age, marital status, parity and pay status. Both groups were free of chronic conditions either associated with thromboembolism or constituting contraindications to pregnancy, and were presumably fertile. They were interviewed to provide information on their use of oral contraceptives before hospitalization. Sixty-seven cases and 23 controls had used these products until within one month before they were hospitalized; 11 cases and controls had discontinued use earlier. Duration of use did not affect the risk. There were 57 case-control pairs in which only the case had used an oral contraceptive within one month compared to 13 in which only the control had done so. The relative risk of rhromboembolism for the users is estimated to be 4.4 times that of nonusers. The risk was higher for users of sequential products. It is estimated that 25% of the cases in this series were attributable to oral contraceptives. © 1969, by THE JOHNS HOPKINS UNIVERSITY.