Objective: To study progression of HIV infection in individuals who are free of AIDS-defining clinical disease with CD4+ cell counts < 200 x 10(6)/l.
Design: Prospective and nested case-control study.
Setting: Amsterdam cohort study on HIV infection, The Netherlands.
Participants: Prospective study: 148 asymptomatic HIV-infected individuals with < 200 x 10(6)/l CD4+ cells. Nested case-control study: 58 men with AIDS-free follow-up more than 2 years after CD4 count < 200 x 10(6)/l, compared with 63 who progressed to AIDS within 2 years.
Main outcome measures: Progression to AIDS according to the 1987 Centers for Disease Control and Prevention case definition and death.
Results: Median AIDS-free interval was 22 months, median interval to death 41 months. Presence of syncytium-inducing (SI) HIV variants, HIV p24 antigen, and a low T-cell response after stimulation with phytohaemagglutinin (PHA) were independent predictors of progression to AIDS. Probability of 1 year AIDS-free survival varied between 89 and 38% by the presence or absence of these additional markers. Effect of early treatment could only be detected in men with HIV p24 antigen and SI variants. Case-control analysis showed similar changes over time regarding prognostic markers in both groups although at a lower rate in the AIDS-free men. Eight men remained AIDS-free more than 4 years, SI variants were absent in seven, and all eight were p24-seronegative.
Conclusions: HIV-infected individuals can remain disease-free for more than 4 years with very low CD4+ cell counts, provided that they lack other progression markers: SI variants, p24 antigen and a low PHA-induced T-cell reactivity. A beneficiary effect of early treatment may be limited to men with SI variants and/or p24 antigen.