Outcomes of extended duration therapy for drug-susceptible cavitary pulmonary tuberculosis

Background: Extending the continuation phase treatment duration is recommended to improve outcomes of drug-susceptible cavitary pulmonary tuberculosis (TB), but limited data are available on extended treatment outcomes.

Methods: We evaluated outcomes of 67 patients with drug-susceptible cavitary pulmonary TB who had received extended therapy. The primary endpoint of our study was the rate of a favorable outcome (cured or treatment completion without recurrence).

Results: Of the 67 patients, 40 (59.7%) were culture negative and 27 (40.3%) were culture positive two months after treatment initiation. The median treatment duration was 275 days. Extended duration therapy resulted in a 100% treatment success rate and 2.5% recurrence rate in patients with a negative culture at month 2. However, patients with a positive culture at month 2, showed a 74.1% treatment success rate and 8.0% recurrence rate (P<0.001 and P=0.554, respectively). In multivariable analyses, positive culture at month 2 was associated with greater odds of unfavorable outcomes (adjusted OR, 17.04, 95% CI, 1.68-177.92).

Conclusions: While extending the continuation phase was associated with favorable outcomes in pulmonary TB patients with negative culture at month 2, the same could not be achieved in those with positive culture at month 2, suggesting that this condition might not be overcome by merely extending the continuation phase.