Setting: Tertiary level tuberculosis (TB) institute in Delhi, India.
Objective: To study the risk factors for new pulmonary TB (PTB) patients failing treatment.
Design: Prospective case-control study. The profile of new PTB patients failing treatment (i.e., sputum smear-positive at 5 months of treatment) and responders under the Revised National Tuberculosis Control Programme (RNTCP) were compared and risk factors associated with treatment failure were analysed.
Results: A total of 42 treatment failure cases and 76 controls were enrolled in the study. The presence of cavity on chest X-ray (CXR), sputum acid-fast bacilli (AFB) smear positivity at 2 months of treatment and the number of interruptions in treatment were independently associated with failures. Among failure patients at 5 months, 17 (40.5%) had negative sputum culture for Mycobacterium tuberculosis, and only six (14.3%) had multidrug-resistant TB (MDR-TB). When put on retreatment, patients with smear-positive, culture-negative sputum had cure rates of 88.2% compared to 28.6% among culture-positive patients.
Conclusions: The presence of cavity on CXR, sputum smear positivity at 2 months of treatment and the number of interruptions of treatment are risk factors for failure. Among failures based on smear examination, the prevalence of MDR-TB is low and many patients have negative cultures for M. tuberculosis. Smear positivity at the end of treatment may not be a reliable indicator of treatment failure.