Zidovudine therapy improves survival in
advanced human immunodeficiency virus (HIV) infection and delays progression from earlier stages to advanced stage of HIV disease. The duration of the benefit
of zidovudine therapy, however, may be limited.
To quantitate the duration of the survival
benefit of zidovudine therapy in a heterogeneous patient population receiving care for HIV infection in an
We analyzed data from 393 HIV-infected patients with CD4+ cell counts of 0.5 × 109/L (500 cells/μL)
or less who first presented for care at The Johns Hopkins
HIV Clinic, Baltimore, Md, from July 1989 through December 1993. Follow-up extended to a maximum of 3 years
(median, 2 years). Survival probabilities in patients who
received and who did not receive zidovudine therapy were
analyzed by Kaplan-Meier methods and by multivariate
Cox proportional hazards regression analysis adjusting for
both time-dependent and fixed prognostic covariates.
Adjusting for baseline differences in CD4+ cell
count, clinical stage of HIV disease, and prophylaxis
for Pneumocystis carinii pneumonia, Cox regression
analysis showed a significant effect of zidovudine compared with no treatment on the risk of dying during
the first year of therapy (relative hazard for death,
0.32; 95% confidence interval [CI], 0.18 to 0.59).
However, analysis of the time-dependent effect of
zidovudine therapy showed that there was a diminishing relative hazard between treatment and no treatment of 0.75 (95% CI, 0.45 to 1.26) at 1 to 2 years of
therapy and a relative hazard of 1.61 beyond 2 years
(95% CI, 0.70 to 3.71).
The survival advantage of zidovudine
therapy is time dependent, lasting between 1 and 2 years
in patients with CD4+ cell counts of 0.5 × 109/L or less.
Alternative antiretroviral treatment may be indicated at
that time.(Arch Intern Med. 1996;156:1073-1077)