title: Utility of absolute lymphocyte count as a surrogate marker of CD4 cell counts: Is it useful?
abstract: BACKGROUND
  Human immunodeficiency virus (HIV) management has witnessed paradigm changes over the past decade. In the early era, Absolute lymphocyte counts (ALC) were used as an inexpensive, indirect marker of immunity status. With time, CD4 lymphocyte counts and HIV RNA levels have become a standard of care for follow up of people living with HIV/AIDS (PLHA). Wide disparities between resource rich and poor countries, rekindles the need for an inexpensive surrogate marker for CD4 lymphocyte counts. Multiple studies in the past including one by Sen S et al, in 2011 did not validate ALC as a surrogate marker of CD4 lymphocyte counts and had recommended a similar study at another centre to validate the same.(1) Recently few publications have suggested that ALC may be used as a proxy marker to CD4 lymphocyte counts in resource poor areas.(2) With this backdrop we decided to evaluate the association if any, of ALC as a surrogate marker to CD4 lymphocyte counts.
  
  
  METHODS
  ALC and CD4 lymphocyte counts measurements of 241 patients at our HIV/AIDS referral centre were assessed over a period of 13 months.
  
  
  RESULTS
  Pearson correlation coefficient, coefficient of determination and standard statistical methods revealed modest linear correlation between ALC and CD4 lymphocyte counts which was statistically significant but did not have clinical significance.
  
  
  CONCLUSIONS
  We recommend that time has come to call curtains down on ALC as a surrogate marker for CD4 lymphocyte count.
authors.affiliation: Associate Professor, Dept of Internal Medicine, Armed Forces Medical College, Pune 40, India.
authors.forename: Amitabh
authors.initials: A
authors.lastname: Sagar
authors.affiliation: Graded Specialist (Medicine), 166 Military Hospital, C/o 56 APO, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Pathak
authors.affiliation: Graded Specialist (Ophthalmology), Military Hospital, Shillong, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Ambiya
authors.affiliation: Professor & Head, Dept of Internal Medicine, Armed Forces Medical College, Pune 40, India.
authors.forename: Nardeep
authors.initials: N
authors.lastname: Naithani
authors.affiliation: Classified Specialist (Dermatology), Command Hospital (Southern Command), Pune 40, India.
authors.forename: Biju
authors.initials: B
authors.lastname: Vasudevan
authors.affiliation: ADH, 33 Corps, C/o 99 APO, India.
authors.forename: Sunil
authors.initials: S
authors.lastname: Agrawal
keywords: CD4 lymphocyte counts; Human immunodeficiency virus; Surrogate marker