Predictors of recurrent TB in sputum smear and culture positive adults: a prospective cohort study

OBJECTIVE: To explore simple inexpensive non-culture based predictors of recurrent pulmonary tuberculosis (PTB). SETTING AND STUDY POPULATION: HIV-infected and uninfected adults with the first episode of smear positive, culture-confirmed pulmonary tuberculosis in a high tuberculosis burden country. DESIGN: A nested prospective cohort study of participants with pulmonary tuberculosis (PTB) presenting to a hospital out-patient clinic. RESULTS: A total of 630 TB culture confirmed participants were followed up for eighteen months of which 57 (9%) developed recurrent recurrent TB. On univariate analysis,4.7% low grade(1+) pre-treatment sputum smear participants developed recurrent tuberculosis Vs 8.8% with high grade(3+) smears (OR=0.31,95%CI: 0.10-0.93, p=0.037).On multivariate analysis: participants with extensive fibro-cavitation had a high risk of recurrent TB Vs minimal end of treatment fibro-cavitation (18%Vs12%, OR=2.3,95%CI:1.09-4.68, p=0.03). Weight gain with HIV infection was assosciated with a high risk of recurrent TB Vs weight gain with no HIV infection(18%Vs 6%, OR=6.8,95%CI:165-27.83, p=0.008) where as weight gain with a low pre-treatment high bacillary burden was assosciated with a low risk of recurrent TB Vs weight gain with a high pre-treatmentbacillary burden(6.5%Vs7.9%, OR=0.2,95%CI:0.05-0.79, p=0.02). CONCLUSION: Extensive end of treatment pulmonary fibro-cavitation, high pre-treatment bacillary burden with no weight gain and HIV infection could be reliable predictors of recurrent tuberculosis.