Revista de SIDA e investigación clínica

Utility of Total Lymphocyte Count as an Affordable Surrogate for CD4 Lymphocyte Count in HIV Infected Nepali Patients

Abstract

Sunil Poudel, Suresh Prajapati, Buddha Laxmi Prajapati, Rama Gyawali, Swosti Acharya, Binod Kumar Yadav and Bishnu Prasad Uppadhya

Introduction: AIDS is a disease of human immune system caused by Human Immunodeficiency Virus. Immunologically it is defined as the condition characterized by CD4 cell count less than 200 cells/mm3. In developing countries the resource are limited so that CD4 count is not easily available in every parts of the country and is too expensive to afford. The Total lymphocyte count (TLC) has been found to be an inexpensive and useful surrogate marker of CD4 count for staging disease, timing of initiation of Antiretroviral Therapy (ART) and response to ART.

Objective: To study the relationship between the T-cell subsets (CD3 and CD4) in HIV patient and to evaluate TLC as a surrogate marker of CD4 T-cell count. Methods: A total of 303 samples were evaluated from July 2010 to September 2010 at NPHL for this study. The blood sample were analyzed by FACS count and the result were analyzed by SPSS 16.0 to determine sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) to find out the relationship between the T cells subsets and evaluate TLC as a surrogate marker of CD4 T cell count for the diagnosis of CD4 count<200 cell/ mm3 and <350 cell/mm3.

Results: There is a strong co-relation between CD4 count and TLC (r=0.714, p<0.01) and CD4 count and CD3 count (r=0.707, p<0.01). A threshold value of 1,400 cell/mm3, we found a maximal combination of sensitivity (70.1%), specificity (81.4%) and NPV (88.9%), but PPV is only 56.2% for a CD4+ T cell count<200 cell/mm3. A CD3 count of <1000 cell/mm3 would have a maximum combination of sensitivity (72.7%), specificity (81%) and NPV (89.7%) but PPV is only 56.6% for CD4 T-cell count<200 cell/mm3.

Conclusion: Total lymphocyte count may provide a simple and cost effective alternative for prioritizing therapy initiation in resources-limited settings. Our study showed a good co-relation (Pearson) of CD4 count with CD3 and TLC, result suggest that, if appropriately validated, judicious application of total lymphocyte counts could overcome one of the practical obstacles to more widespread provision of ART in resource-poor settings.