November 19, 1999
The initial CD4 cell and plasma HIV-1 responses of 600 patients were examined. Patients were included if they had CD4 cell counts <500/mm3 within 2-4 months of receiving their first HAART regimen. Patients were categorized as having favorable, discordant, or unfavorable responses. Patients with favorable responses (Group 1) experience a 1.7-log decline in HIV-1 RNA and a 103-cell increase in CD4 count. Patients with discordant responses (Group 2) had a 0.3-log increase in plasma HIV-1 RNA and a 77-cell increase in CD4 count, or a 1.4-log decrease in plasma HIV-1 RNA but an 80-cell decrease in CD4 count (Group 3). Those with an unfavorable response (Group 4) had a 0.2-log increase in plasma HIV-1 RNA and a 69-cell decrease in CD4 count. Discordant initial responses (increased CD4 count and increased plasma HIV-1 RNA) were associated with the extent of antiretroviral therapy prior to initiating a HAART regimen. The magnitude of the increase in CD4 count among discordant patients was lower than for patients with favorable responses (decreased HIV-1 RNA, increased CD4 count).
This study clearly documents the discordant responses to antiretroviral therapy, but does not provide an explanation for their occurrence. In a previously reported study, Grabar et al.  analyzed data on 2236 PI-naive patients who initiated combination therapy with 2 NRTIs and a PI. In that study, the risk of clinical progression was significantly higher for patients without a CD4 response as compared to responders. Patients who had virologic responses but were immunologic non-responders also were at significantly greater risk of disease progression. Taken together, these results suggest that whereas the change in plasma HIV-1 RNA is an important predictor of treatment outcome, the increase in CD4 lymphocyte count is an important component of treatment benefit.
1. Grabar S, Costagliola D. Clinical outcoms of patients under HAART with discordant response to CD4 and viral load at 6 months [Abstract 169]. 6th Conference on Retroviruses and Opportunistic Infections, Chicago, Ill, 1999.