Predictors of long-term increase in CD4+ cell counts in human immunodeficiency virus-infected patients receiving a protease inhibitor-containing antiretroviral regimen

The temporal relationships between plasma human immunodeficiency virus (HIV) RNA levels and evolution of CD4(+) cell counts was studied, using a 2-slope longitudinal mixed model, in 988 patients prospectively enrolled at the initiation of a protease inhibitor-containing regimen of antiretroviral therapy. The short-term slope (baseline through month 4) for mean change in CD4(+) cell count was +21.2 cells/mm(3)/month, and the long-term slope (month 4 through month 24) was +5.5 cells/mm(3)/month. Compared with results from patients without viral response, the long-term slope was 2.5 cells/mm(3)/month higher in patients who had plasma HIV RNA levels of <500 copies/mL at month 4 (P < .001). It was significantly lower after a rebound in plasma HIV RNA level to greater than or equal to500 copies/mL (P < .0001), varied according to plasma HIV RNA level at the time of rebound, and was negative only when the plasma HIV RNA level at rebound was ≥10, 000 copies/mL. If CD4(+) cell counts can remain elevated despite virologic treatment failure, such a discrepant response may be transient in patients who have a high plasma HIV RNA level at the time of treatment failure.