CD4 count and the risk for death in patients infected with HIV receiving antiretroviral therapy

To investigate the relation between CD4 count and the immediate hazard of dying in patients receiving zidovudine (azidothymidine [AZT])-based antiretroviral therapy.

A research hospital that recruits patients from the entire United States.

Retrospective analysis of a cohort of patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex participating in long-term zidovudine-based antiretroviral protocols.

Fifty-five patients with human immunodeficiency virus (HIV) infection and either AIDS or severe AIDS-related complex who were followed for as many as 4 years while they received antiretroviral therapy.

CD4 counts were measured.

Ten patients are known to be alive and 1 was lost to follow-up. Of the 44 patients who are known to have died, the CD4 range was known within 6 months of death in 41. All but 1 of these 41 assessable deaths occurred in patients whose CD4 counts were known to have fallen below 50 CD4 cells/mm3 (P less than 10(-10)). The hazard of dying in the cohort ranged from 0 deaths/patient-month (95% CI, 0 to 0.008 deaths/patient-month) in patients with 200 or more CD4 cells/mm3 to 0.07 deaths/patient-month (CI, 0.050 to 0.094 deaths/patient-month) in patients with fewer than 50 CD4 cells/mm3. For the patients who died and whose cases were assessable, the mean of the last three CD4 counts obtained before death was 7.7 CD4 cells/mm3 (CI, 0.9 to 63.3 cells/mm3). The median survival of patients once their CD4 counts fell below 50 CD4 cells/mm3 was 12.1 months (CI, 7.2 to 19.4 months).

In a carefully followed cohort treated with zidovudine-based antiretroviral therapy, nearly all deaths occurred in patients with fewer than 50 CD4 cells/mm3. These findings may have implications in the monitoring of patients with AIDS and in the use of CD4 count as a clinical trials end point for the antiretroviral therapy of HIV infection.