To evaluate the relationship between early CD4(+) lymphocyte recovery on antiretroviral therapy (ART) and subsequent survival among low body mass index (BMI) HIV-1-infected adults. Retrospective analysis of a large programmatic cohort in Lusaka, Zambia. We evaluated ART-treated adults enrolled in care for more than 6 months. We stratified this study population according to World Health Organization (WHO) malnutrition criteria: normal (BMI >or=18.5 kg/m(2)), mild (17.00-18.49), moderate (16.00-16.99), and severe (<16.0). We used Cox proportional hazards regression to estimate the subsequent risk of death associated with absolute CD4(+) cell count change over the first 6 months on ART. To account for effect modification associated with baseline CD4(+) cell count, a weighted summary measure was calculated. From May 2004 to February 2009, 56,612 patients initiated ART at Lusaka district clinics; of these, 33 097 (58%) were included in this analysis. The median change in 0-6 month CD4(+) cell count in each baseline BMI strata varied from 127 to 131 cells/microl. There was a statistically significant, inverse association between baseline BMI and the post 6-month hazard for mortality only among those patients with less than 100 cells/microl increase in the first 6 months of ART. A CD4(+) cell count increase of at least 100 cells/microl over the first 6 months of ART was not associated with a higher hazard for mortality, regardless of baseline BMI. Low baseline BMI and attenuated CD4(+) cell count response at 6 months had a compounding, negative impact on post 6-month survival. Specific guidelines for monitoring ART response using immunologic criteria may be warranted for low BMI patients.
