Cohort profile: the KDCA-Tuberculosis-NHIS cohort linking tuberculosis surveillance and health insurance data in Korea.

Despite a steady decline in incidence, tuberculosis (TB) remains a substantial public health burden in Korea, particularly among older adults. Existing national TB surveillance systems lack sufficiently comprehensive data to assess long-term outcomes and health disparities. The K-TB-N cohort integrates data from 3 national sources: the Korean Tuberculosis Surveillance System (2011-2022), the National Health Insurance Database (2010-2022), and mortality data from Statistics Korea (2010-2022). After data cleaning and linkage, the final cohort included 373,812 patients (375,440 episodes) with either drug-susceptible TB or drug- resistant TB. TB notifications declined by approximately 60% over the study period, while the median patient age continued to rise. Treatment success improved over time, accompanied by reductions in lost to follow-up. However, mortality during treatment increased, with more than half of deaths attributed to non-TB causes such as pneumonia, cancer, and cardiovascular disease. Post-treatment mortality also remained high, particularly among patients with drug-resistant TB. The K-TB-N cohort provides a comprehensive, linked dataset for advancing research on TB epidemiology, treatment outcomes, comorbidities, and health disparities. It enables evaluations of public health interventions, long-term prognosis, and strategies for post-TB care. This cohort will remain a valuable resource for shaping data-driven TB control policies in aging and high-burden settings.