title: Validation of the proposed World Health Organization staging system for disease and infection in a cohort of intravenous drug users.
abstract: OBJECTIVE
  To assess the prognostic utility of the clinical criteria of the World Health Organization's (WHO) proposed staging system for HIV disease and infection in a cohort of intravenous drug users (IVDU) from the ALIVE study.
  
  
  METHODS
  All study subjects known to be HIV-seropositive were included in this analysis. Subjects were classified as WHO clinical stage 1, 2, or 3 at their initial seropositive evaluation. Product-limit estimates and Cox proportional hazard models were used to compare time of progression to AIDS (stage 4) for the first three clinical stages.
  
  
  RESULTS
  Of the original cohort of 2921 IVDU in the ALIVE study, 694 were known to be HIV-positive by January 1992. At the time of their index visit, 49% of the cohort were WHO clinical stage 1, 10% stage 2 and 41% were stage 3. Demographic characteristics of the three groups were similar. Product-limit estimates for progression to AIDS over a 3-year period were 6.5% (SE, 1.5%), 10.4% (SE, 4.1%) and 17.1% (SE, 2.5%) for clinical stages 1, 2, and 3, respectively (log-rank P = 0.003). In a proportional hazards model adjusting for race, age, sex and injection status within 6 months prior to enrollment, the hazard for progression to AIDS was 1.51 [95% confidence interval (CI), 0.60-3.77] and 2.39 (95% CI, 1.40-4.08) for stages 2 and 3, respectively, relative to stage 1.
  
  
  CONCLUSIONS
  This study, in a population of IVDU, supports the utility of the WHO staging system in predicting progression from HIV seropositivity to AIDS on the basis of clinical signs and symptoms.
authors.affiliation: Department of Epidemiology, Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland.
authors.forename: R B
authors.initials: RB
authors.lastname: Aylward
authors.forename: D
authors.initials: D
authors.lastname: Vlahov
authors.forename: A
authors.initials: A
authors.lastname: Muñoz
authors.forename: E
authors.initials: E
authors.lastname: Rapiti
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D005260:Female; D006679:HIV Seropositivity / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011379:Prognosis; D016016:Proportional Hazards Models; D015819:Substance Abuse, Intravenous; D013997:Time Factors; D014944:World Health Organization