Utility of total lymphocyte count as a surrogate marker for CD4 counts in HIV-1 infected children in Kenya

BMC Infectious Diseases

Research Article

Elizabeth Maleche-Obimbo¹  Nyawira Githinji¹  Dalton C Wamalwa¹  Dorothy Mbori-Ngacha¹  Moses Nderitu² 

[1]Department of Pediatrics and Child Health, University of Nairobi, Nairobi, Kenya

[2]Kenya Medical Research Institute-Wellcome Trust Research Program, Nairobi, Kenya

关键词: Total Lymphocyte Count;    TLC;    CD4;    HIV;    Children;    surrogate marker;   

DOI  :  10.1186/1471-2334-11-259

 received in 2010-12-30, accepted in 2011-09-30,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundIn resource-limited settings, such as Kenya, access to CD4 testing is limited. Therefore, evaluation of less expensive laboratory diagnostics is urgently needed to diagnose immuno-suppression in children.ObjectivesTo evaluate utility of total lymphocyte count (TLC) as surrogate marker for CD4 count in HIV-infected children.MethodsThis was a hospital based retrospective study conducted in three HIV clinics in Kisumu and Nairobi in Kenya. TLC, CD4 count and CD4 percent data were abstracted from hospital records of 487 antiretroviral-naïve HIV-infected children aged 1 month - 12 years.ResultsTLC and CD4 count were positively correlated (r = 0.66, p < 0.001) with highest correlation seen in children with severe immuno-suppression (r = 0.72, p < 0.001) and children >59 months of age (r = 0.68, p < 0.001). Children were considered to have severe immuno-suppression if they met the following WHO set CD4 count thresholds: age below 12 months (CD4 counts < 1500 cells/mm3), age 12-35 months (CD4 count < 750 cells/mm3), age 36-59 months (CD4 count < 350 cells/mm3, and age above 59 months (CD4 count < 200 cells/mm3). WHO recommended TLC threshold values for severe immuno-suppression of 4000, 3000, 2500 and 2000 cells/mm3 for age categories <12, 12-35, 36-59 and >59 months had low sensitivity of 25%, 23%, 33% and 62% respectively in predicting severe immuno-suppression using CD4 count as gold standard. Raising TLC thresholds to 7000, 6000, 4500 and 3000 cells/mm3 for each of the stated age categories increased sensitivity to 71%, 64%, 56% and 86%, with positive predictive values of 85%, 61%, 37%, 68% respectively but reduced specificity to 73%, 62%, 54% and 68% with negative predictive values of 54%, 65%, 71% and 87% respectively.ConclusionTLC is positively correlated with absolute CD4 count in children but current WHO age-specific thresholds had low sensitivity to identify severely immunosuppressed Kenyan children. Sensitivity and therefore utility of TLC to identify immuno-suppressed children may be improved by raising the TLC cut off levels across the various age categories.

【 授权许可】

Unknown   
© Githinji et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.