The Incidence and Factors Associated with Relapse of Tuberculosis Patients in The Health Region 7, Thailand

Abstract

Tuberculosis (TB) remains a significant global public health concern and a leading cause cause of death in 1 in 10 of the world's population. Although there was a declining trend in TB incidence and treatment success in Thailand between 2019 and 2022, relapse rates have shown an increasing trend, especially in Health Region 7.

The purpose of this retrospective cohort design was to examine the incidence of recurrence, recurrence-free probability, and factors associated with tuberculosis recurrence among patients in Health Region 7 of Thailand. The study population consisted of 834 TB patients who were registered in the National Tuberculosis Information Program (NTIP) database of the Ministry of Public Health, Thailand, and whose treatment outcomes were recorded as either cured or treatment completed between January 1^st, 2019, and December 31^st, 2021. Secondary data was extracted from the NTIP database using a standardized data collection form for the period of January 1^st, 2019, to December 31^st, 2021, and followed from the date of treatment success (cured or treatment completed) until recurrence or the end of the study on December 31^st, 2023. The incidence rate of TB recurrence was estimated using the Kaplan–Meier method, and multivariable analysis of associated factors was conducted using the Cox regression model.

The results showed that most relapsed patients were male (74.2%) with a mean age of 57.8 (SD=15.1) years. About 55.2% smoked and 49.1% consumed alcohol. The incidence rate of TB relapse was 4.1 per 100 person-months (95% CI: 3.64-4.68), with a median survival time to relapse of 8.5 months (IQR: 8.34-8.94). The significant factors associated with increased relapse risk included older age increasing by 1 year (adjusted Hazard Ratio [aHR]=1.00; 95% CI: 1.00–1.02), smoking (aHR=1.39; 95% CI: 1.00–1.93), alcohol consumption (aHR=1.36; 95% CI: 1.01–1.84), and having diabetes mellitus as a comorbidity (aHR=1.33; 95% CI: 1.03–1.72). In contrast, patients with a body weight of ≥ 50 kilograms at treatment initiation had a significantly lower risk of relapse (aHR=0.62; 95% CI: 0.47–0.81).

This study suggests that TB relapse is associated with both behavioral and clinical factors. Monitoring nutritional status, promoting cessation of smoking and alcohol consumption, and improving care for patients with comorbidities such as diabetes are essential to reduce TB relapse. In addition, strengthening TB screening and early case detection efforts is crucial for timely treatment and for reducing the relapse rate in high-burden regions.