title: Extension of the intensive phase reduces unfavourable outcomes with the 8-month thioacetazone regimen.
abstract: METHODS
  Damien Foundation tuberculosis (TB) control projects in Bangladesh.
  
  
  OBJECTIVE
  To assess the effectiveness of a 1-month extension of the intensive phase for smear-positives at 2 months of an 8-month regimen with a continuation phase consisting of isoniazid (INH) and thioacetazone (Th).
  
  
  METHODS
  A prospective study of two cohorts of newly registered smear-positive cases, with extension of the intensive phase for the control cohort, but not for the study cohort. Culture and drug susceptibility testing (DST) of smear-defined failures and relapses and of random samples of new cases.
  
  
  RESULTS
  Among 8230 study patients (86.7% 2-month conversion) and 7206 controls (83.4% conversion), smear-defined failure or relapse outcome was 3.0% for 2-month smear-negatives vs. 3.1% for 2-month smear-positives with extension (non-significant, NS), and 8.2% for 2-month smear-positives with no extension (P < 0.00001). Culture-confirmed failure and relapse reached 1.9% in 2-month smear-negatives and 1.6% (NS) in 2-month smear-positives with vs. 3.7% (P < 0.001) in 2-month smear-positives with no extension. The relative risk (RR) of non-extension in 2-month smear-positives was 2.4 (cultures) to 2.7 (smears). The same RR and borderline significance was found for non-extension of patients with pan-susceptible strains.
  
  
  CONCLUSIONS
  Extension of the intensive phase considerably reduces failures and relapses with a weaker regimen in patients smear-positive at 2 months. Its effectiveness may vary with extent of initial drug resistance vs. power of the regimen.
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium. avdeun@itg.be
authors.forename: A
authors.initials: A
authors.lastname: Van Deun
authors.forename: K J M
authors.initials: KJ
authors.lastname: Aung
authors.forename: M A
authors.initials: MA
authors.lastname: Hamid Salim
authors.forename: M A
authors.initials: MA
authors.lastname: Ali
authors.forename: M S
authors.initials: MS
authors.lastname: Naha
authors.forename: P K
authors.initials: PK
authors.lastname: Das
authors.forename: M A
authors.initials: MA
authors.lastname: Hossain
authors.forename: E
authors.initials: E
authors.lastname: Declercq
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology; D013828:Thioacetazone / Q000627:therapeutic use*; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D013828:Thioacetazone; D007538:Isoniazid