title: Pre-AIDS mortality in the Edinburgh City Hospital HIV cohort.
abstract: In this paper, we look at the incidence and predictive factors of pre-AIDS mortality among HIV-infected individuals, and injecting drug users (IDUs) in particular, and compare IDUs with non-IDUs. 627 patients (73 per cent IDUs) of the Edinburgh City Hospital HIV Cohort were enrolled pre-AIDS and followed up until September 1994. Analyses were performed using cumulative hazard and cumulative incidence estimators for a competing risks model, the Cox proportional hazards model and the non-parametric hazard estimator of Fusaro et al. (1993). The effects of age and CD4 T-lymphocyte cell count, progressively depleted during HIV progression, were investigated. 60 deaths occurred in AIDS-free patients during follow-up; 25 were drug-related deaths in IDUs. Pre-AIDS mortality was higher among IDUs than non-IDUs (p = 0.07). The cumulative incidences of pre-AIDS death after five years from enrollment were 11 per cent in IDUs and 6 per cent in non-IDUs; the cumulative AIDS incidences were, respectively, 19 per cent and 32 per cent. After eight years, cumulative pre-AIDS death incidence was 15 per cent among IDUs; cumulative AIDS incidence among IDUs was 35 per cent. Both groups had similar risks of medically-related (non-AIDS)-MRNA-death. Age and CD4 count were both individually predictive of MRNA death (relative risks (RRs); 2.1 per decade of life, p < 0.01; and 1.9 for each 100 cells per 100 microliters lost, p < 0.0001), although when used together age was less significant (RR 1.6, p = 0.07). Neither was statistically significant for drug-related mortality, although hazard may be lower in older individuals and may increase with falling CD4 count. The drug-related mortality was 1.1 per cent: 2.3 per cent in the first two years after enrollment, and 0.4 per cent thereafter. We conclude that older HIV-infected individuals are at greater risk of medically-related death before AIDS. This risk increases as CD4 count declines. Drug-related hazard may be greater in younger individuals and may increase as CD4 counts fall, but neither effect was formally significant.
authors.affiliation: Medical Research Council Biostatistics Unit, Institute of Public Health, Cambridge, U.K.
authors.forename: S R
authors.initials: SR
authors.lastname: Seaman
authors.forename: R P
authors.initials: RP
authors.lastname: Brettle
authors.forename: S M
authors.initials: SM
authors.lastname: Gore
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000175:diagnosis / Q000453:epidemiology; D000328:Adult; D000367:Age Factors; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000401:mortality*; D006786:Hospitals, Urban; D006801:Humans; D015994:Incidence; D008297:Male; D016016:Proportional Hazards Models; D012044:Regression Analysis; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D015819:Substance Abuse, Intravenous / Q000401:mortality*; D013997:Time Factors