Reliability of absolute lymphocyte count as a marker to assess the need to initiate antiretroviral therapy in HIV-infected children

Abstract

CD4 counts are a standard laboratory measure of disease progression in HIV-infected children. However, CD4 counting is done by flow cytometry and may not always be possible in every centre treating HIV-infected children in resource-limited countries. Absolute Lymphocyte Count (ALC) can be derived easily by performing a routine white blood cell count. The World Health Organization (WHO) in 2006 had recommended ALC to identify HIV-infected children in need of ART in resource-limited settings, when CD4 cell count is not available. This study aims to assess the reliability of using ALC as a marker for starting antiretroviral therapy (ART) in HIV-infected children in a tertiary hospital setting. Retrospective analysis of 46 HIV-infected children who presented at a pediatric HIV clinic at a tertiary referral centre from 2002-2005. Using WHO 2006 guidelines for cutoff values of ALC and 2008 guidelines for CD4% as a comparative standard, a retrospective analysis was done on ART-naοve HIV-infected children who underwent baseline CD4% and ALC, and sensitivity and specificity of ALC was calculated. Fischer exact two-tailed analysis was used to correlate ALC and CD4 and need for starting ART. Sensitivity of ALC was 27.6% (72.4% were false negatives), specificity was 70.6%, with positive predictive value of 61.5%. On comparison across all clinical stages of disease, only 13/46 children (28.2%) would have been started on ART according to ALC cutoffs versus 29/46 children (63.04%) using CD4 criteria (P value=0.0015). In children with WHO clinical Stage 1 or 2 of disease, only 1/11 (9.1%) children were identified by ALC as requiring ART as opposed to 6/11 (54.5%) children by CD4% (P=0.0635). ALC is an unreliable marker to determine the need for starting ART in HIV-infected children.