Correlation Between CD4 Percent And Total Lymphocyte Count (TLC): TLC Thresholds Are Suboptimal For Initiation Of Antiretroviral Therapy In HIV-Infected Nigerian Children.

摘要

Total lymphocyte count (TLC) has been proposed by the world health organisation (WHO) as an alternative to percentage of CD4+ T-cell to indicate when antiretroviral therapy (ART) should be started in HIV-infected children in resource-poor setting.Objective: To evaluate the relationship between TLC and CD4 % in HIV-positive children in order to know when to initiation antiretroviral therapy (ART).Methods: A retrospective review of clinical and laboratory data of 120 infected children age 4 months to 15 years were selected at random, seen at paediatrics department of University of Maiduguri teaching hospital, Maiduguri from 2005 to 2008. Based on the base-line paired TLC-CD4%, degree of correlation between these two measures was determined taking into account of different age groups. The yield of the TLC cut-offs suggested in the WHO 2006 guideline for paediatric ART initiation were assessed. Also the reliability of different TLC cut-offs (above and below the WHO threshold for age group) was determined.Results: Data for 112 HIV-positive children with a mean age of 4.62± 2.87 years were completed for analysis. CD4% and the median TLC were higher in infant and younger children. An overall degree of positive correlation between CD4% and TLC was r= 0.68 (p=0.001). Two out of 5 (40%) children who were eligible for ART using CD4% were placed under incorrect immune categories by TLC thresholds. The reliability of shown wide ranges with sensitivity, specificity, PPV and NPV were maximally aggregated in age group ≤11 months at TLC 3500 for CD4% <25%, in age group 12-35 months at TLC 3500 for CD4% <20% and in age group ≥36 months TLC 2000 for CD4% <15%.Conclusion: Large number of HIV-infected children in developing countries required ART at presentation. Although good correlations exist between TLC and CD4%, the WHO TLC thresholds for initiating ART is suboptimal. More convenient and less expensive technologies are needed in resource-limited settings Introduction New cases paediatric HIV infection has been increasing in Nigeria over the years and the number of HIV positive children requiring ARV was estimated to be 98,040, of which less than 5% actually received ART 1. Disease outcome is usually faster and more serious than in adults, resulting in high mortality and morbidity rates due to serious opportunistic infections1,2. For this reason, early prophylactic measures and specific antiretroviral therapy (ART) are mandatory and without treatment HIV-infected children are likely to die before the age of 3 years1, 2. Absolute CD4 lymphocyte count and percentage and more recently, plasma viral load have been considered the most reliable markers of disease progression in HIV-infected patients1-3 and have been the basis for indicating ART as well as prophylaxis against opportunistic infections. However, these tests require resource and technical expertise both of which are not routinely available in many resource-poor settings such as Nigeria. CD4+ t-lymphocytes constitute at least 60% of the total lymphocyte count (TLC) in the blood. It is therefore reasonable to say that if CD4+ cell fall significantly as occur in HIV infection, it should reflect in concomitant fall in TLC thereby making absolute lymphocyte count a potential surrogate test for CD4 count4. The equipment and skills to perform total white blood cell count and differential are readily available in most hospitals and clinics in resource-poor countries, and performing a TLC costs less than US$1, a fraction of the cost of a CD4 cell measurement5. Several studies in children indicate that TLC independently predicts mortality and correlates with both CD4 percentage and total CD4 cell count4,6,7. However, because TLC is high in children <18 months of age, its reliability as a predictor of mortality in HIV-infected children varies with age and these studies were done in developed countries 7. Based on clinical studies of CD4 count and TLC such as the ones outlined above, the World Heal