title: Should we take a history of prior treatment, and check sputum status at 2-3 months when treating patients for tuberculosis?
abstract: METHODS
  Pinetown, South Africa (1975-1983).
  
  
  OBJECTIVE
  To determine the value of previous treatment history and sputum smear examination at 2-3 months in predicting treatment failure and relapse in tuberculosis patients treated with four drugs given twice weekly for six months under direct observation.
  
  
  METHODS
  Four cohort studies among 562 ambulant adults with culture positive pulmonary tuberculosis, designed to test the effectiveness of isoniazid 600-900 mg, rifampicin 600 mg, pyrazinamide 2-3 g, and streptomycin 1-2 g, given twice weekly. The same drug regimen was given to all patients irrespective of previous treatment history. Therapy was not changed if smears remained positive at 2-3 months.
  
  
  RESULTS
  Positive predictive values of a history of previous treatment for a positive smear at 2-3 months (18.3%), treatment failure (5.2%), and relapse (9.4%) were poor. Although patients with positive smears at 2-3 months were more likely to fail therapy than patients with negative smears (relative risk=4.5, 95% Confidence Interval [CI]: 1.6-12.8), positive predictive value for treatment failure was only 12.5%. Although relapse was more frequent in patients with positive smears than those with negative smears (9.7% vs 6.2%; P=0.4), most patients who relapsed had been smear negative at 2-3 months (18/21).
  
  
  CONCLUSIONS
  A four-drug rifampicin-containing regimen can safely be given twice weekly under direct observation to both new and retreatment cases, and the 2-3 month smear examination can safely be omitted.
authors.affiliation: Centre for Epidemiological Research in Southern Africa, Medical Research Council. davewilk@iafrica.com
authors.forename: D
authors.initials: D
authors.lastname: Wilkinson
authors.forename: S
authors.initials: S
authors.lastname: Bechan
authors.forename: C
authors.initials: C
authors.lastname: Connolly
authors.forename: E
authors.initials: E
authors.lastname: Standing
authors.forename: G M
authors.initials: GM
authors.lastname: Short
mesh_terms: D000328:Adult; D000553:Ambulatory Care; D000904:Antibiotics, Antitubercular / Q000008:administration & dosage / Q000627:therapeutic use; D000995:Antitubercular Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D016001:Confidence Intervals; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D007538:Isoniazid / Q000008:administration & dosage / Q000627:therapeutic use; D008297:Male; D008487:Medical History Taking; D011237:Predictive Value of Tests; D011718:Pyrazinamide / Q000008:administration & dosage / Q000627:therapeutic use; D012008:Recurrence; D019233:Retreatment; D012293:Rifampin / Q000008:administration & dosage / Q000627:therapeutic use; D012307:Risk Factors; D012449:Safety; D012680:Sensitivity and Specificity; D013019:South Africa; D013183:Sputum / Q000382:microbiology*; D013307:Streptomycin / Q000008:administration & dosage / Q000627:therapeutic use; D017211:Treatment Failure; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000904:Antibiotics, Antitubercular; D000995:Antitubercular Agents; D011718:Pyrazinamide; D007538:Isoniazid; D012293:Rifampin; D013307:Streptomycin