Kaposi's sarcoma and central nervous system disease: a real association oran artifact of the control group?

Objectives: To test the hypothesis that Kaposi's sarcoma (KS) protects agai nst four central nervous system (CNS) diseases in HIV-1-infected individual s. Study population and design: The study population of 9404 subjects included participants in Terry Beirn Community Programs for Clinical Research on AI DS (CPCRA) protocols who were enrolled between September 1990 and September 1998. This was an observational study. Methods: Proportional hazards regression was used to estimate adjusted rela tive risks for predictors of four central nervous system diseases. Covariat es included occurrence of Kaposi's sarcoma, occurrence of other opportunist ic infections or malignancies, baseline CD4+ count, and other baseline char acteristics. Results: Among the 5944 participants without progression to AIDS at entry, 451 developed a CNS disease. The adjusted relative risk of any CNS disease for those who developed Kaposi's sarcoma versus those who did not develop a ny AIDS-defining event was 1.41 [95% confidence interval (Cl), 0.98-2.03; P = 0.06]. In contrast, the adjusted relative risk of any CNS disease for th ose with Kaposi's sarcoma versus those with some other non-Kaposi's sarcoma AIDS-defining event was 0.37 (95% Cl, 0.24-0.57; P < 0.0001). Among the 34 60 participants with progression to AIDS at entry, the adjusted relative ri sk of any CNS disease for those with Kaposi's sarcoma versus those with som e other non-Kaposi's sarcoma AIDS-defining event was 0.71 (95% Cl, 0.40-1.2 5; P = 0.23). Conclusions: Our analyses indicate that the risk of CNS disease associated with Kaposi's sarcoma depends strongly on the reference or control group ch osen. When compared to individuals with other non-Kaposi's sarcoma AIDS-def ining diseases, Kaposi's sarcoma is associated with a lower risk of CNS dis ease in HIV-1 positive individuals. However, when compared to individuals w ith no AIDS-defining disease or with a similarly mild AIDS-defining disease such as invasive candidiasis, Kaposi's sarcoma is associated with an equiv alent risk of CNS disease. (C) 2000 Lippincott Williams & Wilkins.