Quantifying the risk of tuberculosis recurrence in Asia: A systematic review of hazard estimates.

INTRODUCTION: Recurrence of tuberculosis (TB) is a major challenge to its control in Asia, even though there is a high treatment success rate of drug-susceptible diseases. TB recurrence contributes to ongoing disease transmission in the community, increases drug resistance and leads to higher TB mortality rates. The study aimed to examine and synthesise the current evidence on determinants of TB recurrence occurring after completed treatment in the Asian setting. MATERIALS AND METHODS: The PRISMA 2020 framework is used as a guide for this systematic review. A systematic search in PubMed/MEDLINE, Scopus and Web of Science (WOS) until September 30, 2025 was conducted. The eligible studies were cohort studies implemented in Asian countries and reported post-treatment TB recurrence and adjusted risk estimates. The Newcastle-Ottawa Scale was used to assess the methodological quality of the included studies. Since the methodological heterogeneity is rather significant, a narrative synthesis was conducted. RESULTS: The review included a total of 15 cohort studies with sample sizes ranging from 508 to more than 10 million individuals. TB recurrence was 1.5 to 15.1% or 0.47 to 6.5 per 1,000 person-years, with the highest rates seen within two years of post-treatment. Recurrence risk was higher when there were comorbidities like diabetes, chronic lung or kidney disease, low body mass index and behavioural factors like smoking. Additionally, environmental exposure to fine particulate matter (PM2.5) and socioeconomic disadvantage were also significant variables. Protective variables observed were high levels of treatment compliance, extended treatment period, the use of fixeddose combination (FDC) therapy, treatment during the directly observed therapy (DOT) era, smoking cessation, and residential greenness. The quality of the included study was moderate to high. CONCLUSION: Multiple determinants drive TB recurrence; thus, improving post-treatment surveillance as well as integrating clinical, behavioural and environmental interventions are important to reduce the incidence and mortality of TB recurrence cases.