title: A nested case-control study on treatment-related risk factors for early relapse of tuberculosis.
abstract: This nested case-control study aimed at evaluating treatment-related risk factors of relapse of tuberculosis under a service program of directly observed treatment. Out of 12,183 patients with pulmonary tuberculosis who completed treatment within 1 year, 113 relapsed within 30 months after commencement of therapy. The overall 30-month relapse rate was 0.9% (95% confidence interval [CI] 0.8-1.1%). On matching 113 cases with 226 control subjects in a conditional logistic model, thrice-weekly treatment increased the risk of relapse in comparison with daily treatment (odds ratio 3.92, 95% CI 1.78-8.63), whereas prolonging both intensive phase and overall treatment by 50% or more protected against relapse (odds ratio 0.24, 95% CI 0.08-0.70). When pretreatment culture was positive and cavitation was absent, the 30-month relapse rate for standard thrice-weekly regimen was 1.1% (95% CI 0.6-2.0%). The corresponding rates in the presence of cavitation were 7.8% (95% CI 4.0-14.6%) for standard thrice-weekly regimen; 3.3% (95% CI 1.9-5.5%) for standard daily regimen; 0.5% (95% CI 0.1-2.6%) for extended thrice-weekly regimen; and 0.4% (95% CI 0.1-0.9%) for extended daily regimen. Further studies are required to reduce the risk of relapse under program settings.
authors.affiliation: Tuberculosis and Chest Service, Department of Health, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR, China. ymtcc@dh.gov.hk
authors.forename: Kwok C
authors.initials: KC
authors.lastname: Chang
authors.forename: Chi C
authors.initials: CC
authors.lastname: Leung
authors.forename: Wing W
authors.initials: WW
authors.lastname: Yew
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: Ho
authors.forename: Cheuk M
authors.initials: CM
authors.lastname: Tam
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000704:Analysis of Variance; D000995:Antitubercular Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D023801:Directly Observed Therapy; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D013997:Time Factors; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology
chemical_list: D000995:Antitubercular Agents