This study was designed as a multicentre, longitudinal observational study and was carried out between 2006 and 2011. Three hundred and sixty patients were planned to be enrolled across 4 centres, namely AIIMS (New Delhi), SMS Medical College (Jaipur), SVIMS (Tirupati) and BJ Medical College (Ahmedabad); i.e. 90 patients at each centre. Lost to follow-up/default rate of 12% was expected in the study. Recruitment was done from the study sites directly as well as from referrals via nearby DOTS centres, hospitals and chest clinics.