Predictors of relapse among pulmonary tuberculosis patients treated in a DOTS programme in South India.

To identify risk factors associated with relapse among cured tuberculosis (TB) patients in a DOTS programme in South India. Sputum samples collected from a cohort of TB patients registered between April 2000 and December 2001 were examined by fluorescence microscopy for acid-fast bacilli and by culture for Mycobacterium tuberculosis at 6, 12 and 18 months after treatment completion. Of the 534 cured patients, 503 (94%) were followed up for 18 months after treatment completion. Of these, 62 (12%) relapsed during the 18-month period; 48 (77%) of the 62 relapses occurred during the first 6 months of follow-up. Patients who took treatment irregularly were twice more likely to have a relapse than adherent patients (20% vs. 9%; adjusted odds ratio [aOR] 2.5; 95% CI 1.4-4.6). Other independent predictors of relapse were initial drug resistance to isoniazid and/or rifampicin (aOR 4.8; 95% CI 2.0-11.6) and smoking (aOR 3.1; 95% CI 1.6-6.0). The relapse rate among non-smoking, treatment adherent patients with drug-sensitive organisms was 4.8%. The relapse rate under the DOTS programme may be reduced by ensuring that patients take their treatment regularly and are counselled effectively about quitting smoking.