[Untitled]

Cell-associated infectious HIV-1 viral load was measured using semi-quantitative microculture techniques to determine its predictive capability for progression to AIDS or survival among HIV-1 infected injecting drug users (IDU) and homosexual men (HM). The authors followed 296 IDU and 240 HM from February 1992 through September 1995 for: (i) death, (ii) AIDS, and (iii) AIDS or bacterial infection. At baseline, viral load was quantified using microculture techniques to determine infectious units per million peripheral blood mononuclear cells (IUPM). Data were analyzed using standard statistical methods for survival analysis. Of the 536 total participants, 106 died (20%), and 98 of the 481 AIDS-free participants developed AIDS (20%). The relative hazard of AIDS for a viral load of ≥100 IUPM, relative to a negative culture (0 IUPM), was 6.73 (95% CI: 2.23–20.3) after adjusting for risk group, initial CD4+ count, and other covariates. The adjusted relative hazard of death for a viral load of 100 IUPM vs. 0 IUPM was 2.57 (95% CI: 0.97–6.80). Viral load predicted time to death within the