Levels and patterns of neutrophil cell counts over the first 8 years of life in children of HIV-1-infected mothers

Background: Antiretroviral drugs (ARV) as prophylaxis to prevent mother-to-child transmission of HIV results in decreased haematological parameters during and shortly after exposure, with recent data suggesting a more prolonged inhibition of haematopoiesis until at least 18 months. Design: Data on 156 HIV-infected and 1533 uninfected children in the European Collaborative Study followed from birth until at least 8 years of age. Methods: Smoothers and splines were used to elucidate patterns over age; linear mixed effects allowed for repeated measurements. Covariates included the child's HIV-1 infection status, prematurity, gender, race, drug withdrawal symptoms at birth and ARV exposure; effects on neutrophil count were quantified in regression analyses using z-scores (SD from mean) of neutrophil counts obtained after modelling untransformed values using the LMS method. For HIV-infected children, progression to AIDS and ARV therapy were also included. Results: After approximately 4 months of age, neutrophil counts were consistently and substantially lower in HIV-infected children than in uninfected children; in both groups, black children had significantly lower counts than white children across the whole age range. In uninfected children, male gender and ARV exposure were associated with reduced neutrophil count until at least 8 years of age. In HIV-infected children, advanced disease and ARV treatment were significantly associated with neutrophil count. Conclusion: A considerably longer effect of exposure to ARV was shown in uninfected children than previously thought and significant associations were shown between race and gender and neutrophil count, as previously observed for lymphocyte counts. The clinical relevance of these reduced levels of neutrophils requires further investigation.