Utility of total lymphocyte count as a surrogate marker for cd4 cell count in HIV infected children

Abstract

With the HIV pandemic and highly active antiretroviral therapy (HAART) expanding,there is need to evaluate less expensive, more available and accessible bio- methods for detecting level of immunosuppression. WHO guidelines recommend use of total lymphocyte unt (TLC). CD4 and CD4% to depict level of immunosuppression. We therefore evaluated the utilityof TLC as surrogate marker for CD4+ T cell count in HIV infected children in three omprehensive Care Centres (CCCs) in Kenya; New Nyanza Provincial Hospital (NNPGH) in Kisumu Kenyatta national Hospital (KNH) and Mbagathi District Hospital (MDH) in Nairobi We carried out a hospital based retrospective study. Paired data on CD4+ T cell count and TLC were collected from hospital records from HAART naive HIV infected children. Data were categorized into < 12 months, 12 - 35 months. 36-59 months and >59 months age strata.Spearman rho coefficient was used to establish correlation between TLC and CD4 and TLC and CD4% pairs. The sensitivity, specificity. positive and negative predictive values of various TLC cut offs was determined using the WHO CD4+ T cell cut-off values as the gold standard. Results Four hundred and eighty seven HAART naive HIV infected children with a median age of36 months (1-144 months) were enrolled into the study. 46% were females and 54% were males. One hundred and twenty five children were enrolled from NNPGR 186 from MDH and 176 from KNH. Positive correlation was found between TLC and CD4+. Overall correlatiori for whole study population was 0.66 (p<O.OO 1). This correlation varied by geographical region with highest correlation in KNH (r=0.76, p<O.OOl), followed by MDH (r= 0.55. p<O.OOl), then NNPGH (r= 0.54, p<O.OO1). It also varied by age with highest correlation coefficient in children above 59 months of age (r= 0.68, p<O.OO1), lowest in children less than 12 months of age (r=0.45. p<O.OOI).The correlation also varied with severity of immuno suppression; higher in severely immuno suppressed category (r= 0.72. p<O.OO1). lower in the non-severely immunosuppressed (r-0.63, p<O.OOl).