RESPONSE OF CD4 LYMPHOCYTES AND CLINICAL CONSEQUENCES OF TREATMENT USING DDI OR DDC IN PATIENTS WITH ADVANCED HIV-INFECTION

The value of CD4 lymphocyte counts as a surrogate marker in persons wi th advanced human immunodeficiency virus infection during antiretrovir al treatment was assessed using longitudinal models and data from the Terry Beirn Community Programs for Clinical Research on AIDS didanosin e/zalcitabine trial of 467 HIV-infected patients. Patients with AIDS o r two CD4 counts of less than or equal to 300 who fulfilled specific c riteria for zidovudine intolerance or failure were randomized to recei ve either 500 mg didanosine (ddI) daily or 2.25 mg zalcitabine (ddC) p er day. Absolute CD4 counts were recorded at study entry and at as man y as four visits. Patients were followed for clinical disease progress ion and survival. At 2 months, the difference in mean CD4 count from b aseline was + 15.4 cells/mm(3) in the ddI group but - 1.3 cells/mm(3) in the ddC group. Patients assigned to ddI had a greater chance of a C D4 response at 2 months than those on ddC, yet only those in the ddC g roup with a response showed significant improvement in progression of disease or survival compared with ddC nonresponders, ddI responders, a nd ddI nonresponders (p = 0.03). We conclude that a CD4 response does not necessarily correlate with improved outcome and is therefore not a useful surrogate marker in these patients.