More rapid progression to AIDS in older HIV-infected people: the role of CD4+ T-cell counts.

The tendency for older people with HIV infection to progress more rapidly to AIDS than younger people was studied in a group of 111 anti-HIV-positive haemophiliacs followed for up to 10 years from seroconversion. After 7 years of seropositivity, those aged over 30 years at the time of the first positive anti-HIV test had a cumulative progression rate to AIDS of 50%, compared with only 12% for those aged 10-19 years (Kaplan-Meier estimates). Overall, the relative risk of developing AIDS by any given time after seroconversion was 1.45 for each 10 year increase in age (p = 0.002; 95% confidence limits of 1.15, 1.85; Cox proportional hazards model). After adjustment for the CD4+ T-cell count (median of 10 count measurements per patient, fitted as a time-dependent covariate), the relative risk fell to 1.31 but remained statistically significant (p less than 0.05; 95% confidence limits of 1.03, 1.67). This implies that older people may be at higher risk of progression than their younger counterparts, even if their CD4+ T-cell counts are the same. Hence, prophylaxis against opportunistic infections may be indicated at higher CD4+ T-cell counts in older people than in younger people.