CD4 cell count at initiation of ART, long-term likelihood of achieving CD4 >750 cells/mm3 and mortality risk

Abstract

Objectives: We sought to evaluate associations between CD4 at ART initiation (AI), achieving CD4 >750 cells/mm(3) (CD4 >750), long-term immunological recovery and survival.

Methods: This was a prospective observational cohort study. We analysed data from ART-naive patients seen in 1996-2012 and followed ≥3 years after AI. We used Kaplan-Meier (KM) methods and log-rank tests to compare time to achieving CD4 >750 by CD4 at AI (CD4-AI); and Cox regression models and generalized estimating equations to identify factors associated with achieving CD4 >750 and mortality risk.

Results: Of 1327 patients, followed for a median of 7.9 years, >85% received ART for ≥75% of follow-up time; 64 died. KM estimates evaluating likelihood of CD4 >750 during 5 years of follow-up, stratified by CD4-AI <50, 50-199, 200-349, 350-499 and 500-750, were 20%, 25%, 56%, 80% and 87%, respectively (log-rank P < 0.001). In adjusted models, CD4-AI ≥200 (versus CD4-AI <200) was associated with achievement of CD4 >750 [adjusted HR (aHR) = 4.77]. Blacks were less likely than whites to achieve CD4 >750 (33% versus 49%, aHR = 0.77). Mortality rates decreased with increasing CD4-AI (P = 0.004 across CD4 strata for AIDS causes and P = 0.009 for non-AIDS death causes). Among decedents with CD4-AI ≥50, 56% of deaths were due to non-AIDS causes.

Conclusions: Higher CD4-AI resulted in greater long-term CD4 gains, likelihood of achieving CD4 >750, longer survival and decreased mortality regardless of cause. Over 80% of persons with CD4-AI ≥350 achieved CD4 >750 by 4 years while 75% of persons with CD4-AI <200 did not. These data confirm the hazards of delayed AI and support early AI.