title: Superior virologic and treatment outcomes when viral load is measured at 3 months compared to 6 months on antiretroviral therapy.
abstract: BACKGROUND
  Routine viral load (VL) monitoring is utilized to assess antiretroviral therapy (ART) adherence and virologic failure, and it is currently scaled-up in many resource-constrained settings. The first routine VL is recommended as late as six months after ART initiation for early detection of sub-optimal adherence. We aimed to assess the optimal timing of first VL measurement after initiation of ART.
  
  
  METHODS
  This was a retrospective, cohort analysis of routine monitoring data of adults enrolled at three primary care clinics in Khayelitsha, Cape Town, between January 2002 and March 2009. Primary outcomes were virologic failure and switch to second-line ART comparing patients in whom first VL done was at three months (VL3M) and six months (VL6M) after ART initiation. Adjusted hazard ratios (aHR) were estimated using Cox proportional hazard models.
  
  
  RESULTS
  In total, 6264 patients were included for the time to virologic failure and 6269 for the time to switch to second-line ART analysis. Patients in the VL3M group had a 22% risk reduction of virologic failure (aHR 0.78, 95% CI 0.64-0.95; p=0.016) and a 27% risk reduction of switch to second-line ART (aHR 0.73, 95% CI 0.58-0.92; p=0.008) when compared to patients in the VL6M group. For each additional month of delay of the first VL measurement (up to nine months), the risk of virologic failure increased by 9% (aHR 1.09, 95% CI 1.02-1.15; p=0.008) and switch to second-line ART by 13% (aHR 1.13, 95% CI 1.05-1.21; p<0.001).
  
  
  CONCLUSIONS
  A first VL at three months rather than six months with targeted adherence interventions for patients with high VL may improve long-term virologic suppression and reduce switches to costly second-line ART. ART programmes should consider the first VL measurement at three months after ART initiation.
authors.affiliation: Médecins sans Frontières, Khayelitsha, Cape Town, South Africa; benadi11@yahoo.de.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kerschberger
authors.affiliation: Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Boulle
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kranzer
authors.affiliation: Médecins sans Frontières, Khayelitsha, Cape Town, South Africa.|Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Katherine
authors.initials: K
authors.lastname: Hilderbrand
authors.affiliation: Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Michael
authors.initials: M
authors.lastname: Schomaker
authors.affiliation: Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: David
authors.initials: D
authors.lastname: Coetzee
authors.affiliation: South African Medical Unit, Médecins sans Frontières, Cape Town, South Africa.
authors.forename: Eric
authors.initials: E
authors.lastname: Goemaere
authors.affiliation: Médecins sans Frontières, Khayelitsha, Cape Town, South Africa.|Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Gilles
authors.initials: G
authors.lastname: Van Cutsem
mesh_terms: D000328:Adult; D000554:Ambulatory Care Facilities; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006295:Health Resources; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013019:South Africa; D013997:Time Factors; D016896:Treatment Outcome; D019562:Viral Load / Q000187:drug effects*
chemical_list: D019380:Anti-HIV Agents
keywords: HIV; treatment switching; viral load; virologic failure