Absolute CD4+ T-Lymphocyte Count as a Surrogate Marker of Pediatric Human Immunodeficiency Virus Disease Progression

Abstract

Traditionally in pediatric HIV, the CD4+ T-lymphocyte percent is used to monitor disease progression because of the variability in absolute CD4+ T-lymphocyte numbers. Because of the high cost of equipment, sophisticated and delicate technology, most laboratories in resource-limited settings use simple protocols that enumerate only the absolute CD4+ T-lymphocyte counts. We assessed the use of absolute CD4+ T-lymphocyte count as a surrogate marker of pediatric HIV disease progression. We analyzed the CD4+ T-lymphocytes and HIV viral load over a 10-year period (1996-2006) of 97 HIV-infected children enrolled in the Yale Prospective Longitudinal Pediatric HIV Cohort using generalized linear mixed models. Both CD4+ T-lymphocytes and HIV viral load were assessed at baseline and every 2-3 months. The modeling approach used in this study allows the intercept and the rate at which outcome variables change over time to vary across participants. We determined that absolute CD4+ T-lymphocytes count was just as reliable at monitoring pediatric HIV as CD4+ T-lymphocyte percentage. Antiretroviral treatment, regardless of the regimen used, was associated with higher CD+ T-lymphocytes count (P < 0.01). Race was significantly associated with CD4+ T-lymphocytes counts (with lower values for blacks compared with nonblacks; P < 0.01). The presence of other infections was associated with lower CD4+ T-lymphocyte count (P = 0.01) and higher viral load (P < 0.01), respectively. In situations where determination of CD4+ T-lymphocyte percentages is not readily available, the absolute count may provide an affordable and accessible laboratory surrogate marker of HIV disease progression in children.