title: Initial drug resistance and tuberculosis treatment outcomes: systematic review and meta-analysis.
abstract: BACKGROUND
  Despite the increasing prevalence of drug-resistant tuberculosis, most low- and middle-income countries use standardized regimens, without assessment of drug susceptibility.
  
  
  OBJECTIVE
  To perform a systematic review and meta-analysis of the effect of initial drug resistance and treatment regimen on tuberculosis treatment outcomes.
  
  
  METHODS
  PubMed, the Cochrane Central Database of Clinical Trials, and EMBASE were searched for studies published in English from 1965 to June 2007. Additional studies were identified from cited references.
  
  
  METHODS
  Randomized, controlled trials and cohort studies of standardized treatment of previously untreated patients with culture-confirmed pulmonary tuberculosis. Drug-susceptibility testing was done on pretreatment isolates from all patients and from patients with treatment failure or relapse.
  
  
  METHODS
  Two authors reviewed the studies for methods, initial drug resistance, treatment regimens, and outcomes.
  
  
  RESULTS
  Pooled cumulative incidences were computed with random-effects meta-analyses. Association between risk factors and outcomes were determined by using stratified analyses. The cumulative incidence of acquired drug resistance with initially pan-sensitive strains was 0.8% (95% CI, 0.5% to 1.0%) compared with 6% (CI, 4% to 8%) with initially single drug-resistant strains and 14% (CI, 9% to 20%) with initially polydrug-resistant strains. Failure and relapse were most strongly associated with initial drug resistance. Failure was also associated with shorter duration of rifampin therapy and nonuse of streptomycin, whereas the rate of relapse was higher with shorter duration of rifampin therapy and nonuse of pyrazinamide.
  
  
  CONCLUSIONS
  Few studies included HIV-infected persons, and treatment outcomes were pooled despite considerable heterogeneity.
  
  
  CONCLUSIONS
  Treatment outcomes were substantially worse in the presence of initial drug resistance, which has important implications in resource-limited settings in which drug resistance is prevalent.
authors.affiliation: Montreal Chest Institute, McGill University, Montreal, Quebec, Canada.
authors.forename: Woojin
authors.initials: W
authors.lastname: Lew
authors.forename: Madhukar
authors.initials: M
authors.lastname: Pai
authors.forename: Olivia
authors.initials: O
authors.lastname: Oxlade
authors.forename: Daniel
authors.initials: D
authors.lastname: Martin
authors.forename: Dick
authors.initials: D
authors.lastname: Menzies
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents