title: Evaluation of WHO immunologic criteria for treatment failure: implications for detection of virologic failure, evolution of drug resistance and choice of second-line therapy in India.
abstract: BACKGROUND
  Routine HIV viral load (VL) testing is not available in India. We compared test performance characteristics of immunologic failure (IF) against the gold standard of virologic failure (VF), examined evolution of drug resistance among those who stayed on a failing regimen because they did not meet criteria for IF and assessed implications for second-line therapy.
  
  
  METHODS
  Participants on first-line highly active antiretroviral therapy (HAART) in Bangalore, India, were monitored for 24 months at six-month intervals, with CD4 count, VL and genotype, if VL>1000 copies/ml. Standard WHO criteria were used to define IF; VF was defined as having two consecutive VL>1000 copies/ml or one VL>10,000 copies/ml. Resistance was assessed using standard International AIDS Society-USA (IAS-USA) recommendations.
  
  
  RESULTS
  Of 522 participants (67.6% male, mean age of 37.5; 85.1% on nevirapine-based and 40.4% on d4T-containing regimens), 57 (10.9%) had VF, 38 (7.3%) had IF and 13 (2.5%) had both VF and IF. The sensitivity of immunologic criteria to detect VF was 22.8%, specificity was 94.6% and positive predictive value was 34.2%. Forty-four participants with VF only continued on their failing first-line regimen; by the end of the study period, 90.9% had M184V, 63.6% had thymidine analogue mutations (TAMs), 34.1% had resistance to tenofovir, and 63.6% had resistance to etravirine.
  
  
  CONCLUSIONS
  WHO IF criteria have low sensitivity for detecting VF, and the presence of IF poorly predicts VF. Relying on CD4 counts leads to unnecessary switches to second-line HAART and continuation of failing regimens, jeopardizing future therapeutic options. Universal access to VL monitoring would avoid costly switches to second-line HAART and preserve future treatment options.
authors.affiliation: Center for AIDS Prevention Studies and the Division of Infectious Diseases, University of California, San Francisco, CA 94105, USA. snigdhav@gmail.com
authors.forename: Snigdha
authors.initials: S
authors.lastname: Vallabhaneni
authors.forename: Sara
authors.initials: S
authors.lastname: Chandy
authors.forename: Elsa
authors.initials: E
authors.lastname: Heylen
authors.forename: Maria L
authors.initials: ML
authors.lastname: Ekstrand
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D016903:Drug Monitoring / Q000379:methods*; D024882:Drug Resistance, Viral; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology* / Q000821:virology; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D012680:Sensitivity and Specificity; D017211:Treatment Failure; D019562:Viral Load; D014944:World Health Organization
chemical_list: D019380:Anti-HIV Agents
keywords: India; WHO criteria; genotype; immunologic failure; resistance; resource-limited settings; virologic failure