title: Impact of the frequency of plasma HIV-1 RNA monitoring on the outcome of antiretroviral therapy.
abstract: BACKGROUND
  Current guidelines for HIV management recommend monitoring plasma HIV-1 RNA level every 3-6 months in patients on a stable antiretroviral regimen. However, cost is the major obstacle to follow the guidelines in resource-limited settings.
  
  
  OBJECTIVE
  This study aimed to compare the outcome of antiretroviral therapy among HIV-infected patients on a stable regimen who had plasma HIV-1 RNA monitoring once vs. twice yearly.
  
  
  METHODS
  A retrospective cohort study was conducted among HIV-infected patients receiving antiretroviral therapy since 2002 at Chiang Mai University Hospital, Thailand. We evaluated the incidence of virological failure and number of reverse transcriptase (RT) mutations between groups.
  
  
  RESULTS
  Of 551 patients on a stable antiretroviral regimen, 405 (73.5%) and 146 (26.5%) patients had plasma HIV-1 RNA measurement once and twice yearly, respectively. Forty-seven of 405 patients (11.6%) in once-yearly group and 15 of 146 patients (10.3%) in twice-yearly group developed virological failure, giving the incidence rate of 2.03/100 and 1.95/100 person-years, respectively. The probability of virological failure did not differ between groups (p=0.897, log-rank test). The number of RT mutations was not statistically different between groups (all p-values>0.05). The predicting factors for virological failure from a multivariate analysis were adherence rate <95% and baseline CD4 cell count <50 cells/mm3 but not the frequency of HIV-1 RNA monitoring.
  
  
  CONCLUSIONS
  The incidence of virological failure and the number of RT mutations were not different between groups. Therefore, in resource-limited settings, the recommendation to perform plasma HIV-1 RNA measurement once yearly in patients on a stable antiretroviral regimen is justified.
authors.affiliation: Department of Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand. rchaiwar@gmail.com
authors.forename: Romanee
authors.initials: R
authors.lastname: Chaiwarith
authors.forename: Jutarat
authors.initials: J
authors.lastname: Praparattanapan
authors.forename: Nontakan
authors.initials: N
authors.lastname: Nuntachit
authors.forename: Wilai
authors.initials: W
authors.lastname: Kotarathitithum
authors.forename: Thira
authors.initials: T
authors.lastname: Sirisanthana
authors.forename: Khuanchai
authors.initials: K
authors.lastname: Supparatpinyo
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D015331:Cohort Studies; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D015497:HIV-1 / Q000187:drug effects / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000097:blood*; D012189:Retrospective Studies; D013785:Thailand; D017211:Treatment Failure; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents; D012367:RNA, Viral