Application of the World Health Organization system for HIV infection in a cohort of homosexual men in developing a prognostically meaningful staging system
Validation of a modified version of the recently proposed World Health Organization (WHO) staging system for HIV infection and disease in a cohort of homosexual men. Five hundred and thirty HIV-positive men followed for a median of 51 months (range, 1-98 months) were eligible for analysis. Subjects were classified into stages at their first seropositive visit and at all subsequent visits. As of 1 April 1991, 136 subjects (26%) had progressed to stage IV of the modified WHO system on the basis of their CD4 lymphocyte counts, and 78 subjects (15%) had died. Kaplan-Meier estimates for progression to stage IV from stages I, II and III were 52.8 +/- 7.5% over 6.6 years, 58.1 +/- 7.1% over 5.9 years and 66.5 +/- 9.7% over 5.7 years (log-rank P = 0.0001). Estimated median times to stage IV were 6.4, 5.3 and 3.8 years from stages I, II and III, respectively. Estimated median times to death were 10.9, 8.2, 6.3 and 1.7 years from stages I to IV, respectively. Results remained unchanged when CD4 lymphocyte count was replaced with lymphocyte count in the laboratory axis of the staging system. The proposed staging scheme, based on the WHO system, provides a prognostically meaningful classification for HIV infection in a cohort of homosexual men. Furthermore, the use of absolute lymphocyte count as a valid alternative for CD4 lymphocyte count has implications for the applicability of this system in many parts of the world where diagnostic resources are limited.