Risk factors for Kaposi's sarcoma in patients with advanced human immunodeficiency virus disease treated with zidovudine

Background: Although the cause of Kaposi's sarcoma (KS) is unknown, its unique epidemiology suggests that an infectious, sexually transmitted agent or agents may contribute to its pathogenesis. Methods: To assess the natural history of KS associated with the acquired immunodeficiency syndrome and to identify factors associated with its development, data were analyzed from a multicenter, observational cohort study of 1044 persons with the acquired immunodeficiency syndrome or the acquired immunodeficiency syndrome-related complex and a total CD4 cell count of less than 0.25x10⁹/L who were treated with zidovudine between April 1987 and April 1988. Records were reviewed bimonthly. Follow-up continued for 2 years or until death. Results: One hundred thirty-one patients (13%) had KS at study enrollment, and 143 developed KS (14%) during follow-up, with a 2-year actuarial risk of 21%. The probability of KS at 2 years for patients with initial CD4 cell counts of less than 0.1x10⁹/L was 25%, compared with 15% for those with counts of 0.1x10⁹/L or more. By logistic regression, a baseline CD4 cell count of less than 0.1x10⁹/L (relative odds, 1.43; 95% confidence interval, 1.04 to 1.95), homosexuality (relative odds, 3.71; 95% confidence interval, 1.82 to 7.56), cytomegalovirus disease (relative odds, 1.56; 95% confidence interval, 1.01 to 2.41), and white race (relative odds, 1.64; 95% confidence interval, 1.11 to 2.43) were independently associated with KS. Median survival after KS was 408 days, and KS was an independent predictor of death (relative hazard, 1.78; 95% confidence interval, 1.26 to 2.52). Conclusions: Kaposi's sarcoma contributes to human immunodeficiency virus-related morbidity and mortality, especially among male homosexuals. This large cohort study provides further evidence for an association between risk for cytomegalovirus infection and KS.