Proposed 'World Health Organization staging system for HIV infection and disease': preliminary testing by an international collaborative cross-sectional study. The WHO International Collaborating Group for the Study of the WHO Staging System.

OBJECTIVE: To evaluate a universally applicable staging system for HIV infection and disease proposed by the Global Programme on AIDS (GPA) of the World Health Organization (WHO). The system consists of both a 'clinical' and a 'laboratory' axis. The 'clinical axis' is represented by a sequential list of clinical conditions believed to have prognostic significance, which subdivides the course of HIV infection into four clinical stages. The 'laboratory axis' subdivides each clinical stage into three strata according to CD4+ cell or total lymphocyte count.
DESIGN: International cross-sectional study.
SETTING: Twenty-seven clinical centres in 20 countries. PATIENTS AND PARTICIPANTS: A total of 938 confirmed HIV-positive patients, aged at least 13 years. MAIN OUTCOME MEASURES: Presence of the clinical condition belonging to the highest stage and its correlation with recent laboratory data (CD4+ cell counts, total lymphocyte counts, beta 2-microglobulin levels, haemoglobin, haematocrit, erythrocyte sedimentation rate, p24 antigen, p24 antibody and delayed hypersensitivity skin test).
RESULTS: There was general agreement between the proposed attribution of clinical conditions and the corresponding laboratory markers. Significant differences were observed between stages 3 and 4 for seven laboratory markers and between stages 2 and 3 for six, but not between stages 1 and 2, for any of the nine laboratory markers.
CONCLUSIONS: Longitudinal studies are needed to assess whether the proposed system is useful in predicting survival time in patients with HIV disease.