Recurrent pulmonary tuberculosis after treatment success: a population-based retrospective study in China.

Objectives: Post-treatment recurrence remains a challenge for the global control of tuberculosis (TB). This study investigated longitudinal data on pulmonary TB recurrence rates and risk factors for recurrence among successfully treated smear-positive tuberculosis cases in China.

Methods: Between 1st January 2009 and 31st December 2016 we evaluated 33 441 treatment-naïve patients diagnosed with sputum-smear-positive, non-multidrug-resistant TB in Hangzhou, China. We included the data of 9828 patients with TB who were treated successfully.

Results: A total of 4.9% of the cases were recurrent (479/9828), identified within a median observation period lasting 1565 days. Altogether, 51.1% (245/479) of the recurrences occurred within 1 year. The cumulative 2- and 5-year recurrence rates were 3.90% (95% confidence interval (CI) 3.3-4.5%) and 5.4% (95%CI 4.8-6.0%), respectively. Prolonged treatment (over 7 months) occurred in 64.7% (6363/9828), with a median treatment duration of 242 days (interquartile range 195-348 days). Male sex (adjusted hazard ratio (aHR) (95%CI) 1.61 (1.30-2.00), p < 0.001), age 60 years old or older (aHR (95%CI) 2.03 (1.70-2.44), p < 0.001), pulmonary cavity (aHR (95%CI) 1.51 (1.25-1.82), p < 0.001) and sputum positivity at 2 months (aHR (95%CI) 1.39 (1.05-1.81), p 0.02) all increased the risk of TB recurrence. Prolonged treatment was associated with reduced TB recurrence (aHR (95%CI) 0.73 (0.61-0.88), p 0.001).

Conclusions: Recurrence remains a problem for successfully treated patients with sputum-smear-positive pulmonary TB, especially those with independent risk factors. Further analysis of prolonged treatment is required.