title: Total lymphocyte count as a surrogate marker for CD4+ t cell count in initiating antiretroviral therapy at Kenyatta National Hospital, Nairobi.
abstract: OBJECTIVE
  To evaluate the utility of Total Lymphocyte Count (TLC) as a surrogate marker for CD4 + T cell count in antiretroviral (ARV) treatment initiation in a Kenyan population of HIV seropositive patients at Kenyatta National Hospital.
  
  
  METHODS
  Cross-sectional descriptive study.
  
  
  METHODS
  Kenyatta National Hospital, HIV treatment and follow-up outpatient facility; Comprehensive Care Centre, Nairobi, Kenya.
  
  
  METHODS
  Two hundred and twenty five HIV Elisa positive, ARV naive patients visiting the Comprehensive Care Centre between January 2006 to March 2006.
  
  
  RESULTS
  A significant linear correlation was found between TLC and CD4 cell count for the whole group with a Spearman rank correlation of 0.761 (p < 0.01); and was also independently observed in the four WHO clinical stages. The classification utility of TLC 1200 cells/mm3 cut-off was suboptimal; sensitivity 37% specificity of 99% and the NPV of 56%. The receiver operator characteristics (ROC) curve generated an optimal TLC cut-off of 1900 cells/mm3 cut-off to be of greatest utility with a sensitivity of 81.1%, specificity of 90.3%, PPV of 90.8% and NPV of 80.2%. This implies that a TLC cut-off of 1900 cells/mm3 correctly classify eight out of ten HIV positive patients as having a CD4 < 200 cells/mm3 and only misclassify two such patients. Serial CD4 testing can then be performed on the minority of patients who despite a TLC > or = 1900 cells/mm3 are, on basis of clinical data, suspect of more advanced disease warranting ARV therapy. This would reduce the number of patients tested for and focus the application of CD4 testing and thus reduce attendant cost in care provision in CD4 resource poor settings.
  
  
  CONCLUSIONS
  Our data showed a good positive correlation between TLC and CD4 cell count, however the WHO recommended TLC cuto-ff of 1200/mm3 was found to be of low sensitivity in classifying patients as having a CD4 counts < 200 cells/mm3. This would result in underestimation of advanced stage of disease and to withholding ARVs treatment to persons who need treatment. We recommend a TLC cut-off of 1900 cells/mm3 for our population to classify patients as either above or below the CD4 count cut-off of 200 cells/mm3 as an indicator of when to start antiretroviral therapy.
authors.affiliation: Department of Clinical Medicine and Therapeutics, College of Health Sciences, University of Nairobi, Nairobi, Kenya.
authors.forename: B
authors.initials: B
authors.lastname: Gitura
authors.forename: M D
authors.initials: MD
authors.lastname: Joshi
authors.forename: G N
authors.initials: GN
authors.lastname: Lule
authors.forename: O
authors.initials: O
authors.lastname: Anzala
mesh_terms: D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active; D015415:Biomarkers; D018791:CD4 Lymphocyte Count; D003430:Cross-Sectional Studies; D020000:Decision Support Systems, Clinical; D015658:HIV Infections / Q000188:drug therapy*; D006679:HIV Seropositivity; D006801:Humans; D007630:Kenya; D018655:Lymphocyte Count; D008214:Lymphocytes; D016896:Treatment Outcome
chemical_list: D044966:Anti-Retroviral Agents; D015415:Biomarkers