Determinants of sputum conversion at two months of treatment under National Tuberculosis Programme, South India

Background: In India, Revised National Tuberculosis (TB) control programme (RNTCP) offers free diagnosis and treatment for TB, based on the Directly Observed Treatment Short (DOTS) course strategy. Under RNTCP, sputum conversion rate (SCR), at the end of 2 months of treatment is an important operational indicator, which is ideally expected to be 90%. Objectives: The objective of the present work was to investigate the factors associated with low SCR at the end of 2 months of treatment in Sira TB unit, Tumkur District, India. Material and Methods: It is a retrospective cohort study of all new sputum smear-positive patients registered in RNTCP in 2011. Data were retrieved from the TB register maintained at the District TB center. Chi-square and Student’s t-test were used for analysis of the study variables between patients who were sputum positive and sputum negative at the end of 2 months of treatment. Multivariate logistic regression was applied to determine the risk contributed by the variables towards non-conversion of sputum. Results: Of the 268 included patients, 66.7% patients were sputum negative. Patients aged ≥ 45 years were twice prone to be sputum positive (OR = 2.14) (P = 0.007). The odds of being sputum positive after 2 months of treatment was observed to be significantly high (OR = 7.12; 95% C.I. = 1.52–33.22; P = 0.01) for sputum grade 3+ at the time of diagnosis, respectively. Conclusion: Elderly patients with a high bacilli load should be advised and counselled well regarding adherence to treatment. Further, advice should be given on preventing spread of the disease by practising cough hygiene, as they are more infectious than other patients with less sputum-positive grade.