title: Utility of total lymphocyte count as a surrogate for absolute CD4 count in the adult Indian HIV population: A prospective study.
abstract: BACKGROUND
  Standard methods of CD4 counts and plasma viral load estimation require specialized equipment, highly trained personnel and are extremely expensive. This remains a major challenge for the initiation of anti-retroviral therapy for patients in resource-limited settings.
  
  
  OBJECTIVE
  To assess the clinical utility of the total lymphocyte count (TLC) to serve as a surrogate marker for predicting a CD4 counts <350 cell/mm(3) in patients with HIV.
  
  
  METHODS
  A prospective study of 200 consecutive newly detected highly active anti-retroviral therapy (HAART) naïve HIV patients admitted over a one year period was conducted. Linear regression, Pearson correlation and receiver operating characteristic (ROC) curves were used to calculate the relationship between TLC and CD4 counts.
  
  
  RESULTS
  A significant correlation between TLC and CD4 count was observed (r = 0.682, P < 0.001). TLC cut off of 1200 cell/mm(3) as a predictor of CD4 count <350 cell/mm(3) had 73.1% sensitivity, 100% specificity, 100% positive predictive value (PPV) and 51.4% negative predictive value (NPV). Raising the cutoff to 1500 cells/mm(3) improved the sensitivity to 82.1% with 88.2% specificity, 96.5% PPV, 44.4% NPV. The ROC curve demonstrated highest area under curve (AUC = 0.8) for TLC of 1500 cell/mm(3).
  
  
  CONCLUSIONS
  The study showed that TLC cutoff value of 1500 cells/mm(3) was a cost effective surrogate marker for CD4 counts <350 cells/mm(3) in resource-limited settings.
authors.affiliation: Department of Medicine, Kasturba Medical College, Manipal, India.
authors.forename: Suman S
authors.initials: SS
authors.lastname: Karanth
authors.affiliation: Department of Medicine, Kasturba Medical College, Manipal, India.
authors.forename: N R
authors.initials: NR
authors.lastname: Rau
authors.affiliation: Department of Neurosurgery, Adarsha Superspeciality Hospital, Udupi, India.
authors.forename: Anurag
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Department of Community Medicine, Kasturba Medical College, Manipal, India.
authors.forename: Asha
authors.initials: A
authors.lastname: Kamath
authors.affiliation: Department of Medicine, Kasturba Medical College, Manipal, India.
authors.forename: Vikram
authors.initials: V
authors.lastname: Shanbhogue
authors.affiliation: Department of Medicine, Vaalsalya Hospital, Shimoga, Karnataka, India.
authors.forename: B C
authors.initials: BC
authors.lastname: Pruthvi
keywords: CD4 count; human immunodeficiency virus; surrogate marker; total lymphocyte count