Changes in Plasma HIV-1 RNA and CD4+ Lymphocyte Counts and the Risk of Progression to AIDS

Background Clinical trials of antiretroviral drugs can take years to complete because the outcomes measured are progression to the acquired immunodeficiency syndrome (AIDS) or death. Trials could be accelerated by the use of end points such as changes in CD4+ lymphocyte counts and plasma levels of human immunodeficiency virus type 1 (HIV-1) RNA and β2-microglobulin, but there is uncertainty about whether these surrogate measures are valid predictors of disease progression. Methods We analyzed data from the Veterans Affairs Cooperative Study on AIDS, which compared immediate with deferred zidovudine therapy. Patients' plasma levels of HIV-1 RNA and β2-microglobulin were measured in stored plasma. Results Among the 129 patients in the immediate-treatment group, 34 had disease that progressed to AIDS, as compared with 57 of the 141 patients in the deferred-treatment group (P = 0.03). Progression to AIDS correlated strongly with base-line CD4+ lymphocyte counts (P = 0.001) and plasma levels of HIV-1 RNA (P<0....