Changing Clinical Characteristics, Diagnostic Patterns, and Outcomes of Tuberculosis in South Korea: The Korean Tuberculosis Cohort, 2019-2024

BACKGROUND: Tuberculosis (TB) remains a public health concern in South Korea despite declining national notifications. We evaluated temporal changes in clinical characteristics, diagnostic patterns, and treatment outcomes in the Korean Tuberculosis Cohort (KTBC) from 2019 to 2024. METHODS: We retrospectively analyzed prospectively collected data from the multicenter KTBC registry from January 2019 to December 2024. Overall analyses used the full cohort including extrapulmonary TB; radiographic, microbiologic, bronchoscopy, and drug-susceptibility analyses were restricted to patients with pulmonary involvement. Calendar year was treated as an ordinal variable, with trends tested by linear regression or the Cochran-Armitage test (P for trend). RESULTS: Among 33,826 patients, the proportion aged ≥65 years increased from 46.9% in 2019 to 54.8% in 2024 and any comorbidity from 59.6% to 71.5%. Among 26,271 patients with pulmonary involvement, chest radiography (CXR) findings suspicious for TB decreased from 71.2% to 42.3% and CXR cavitation from 18.0% to 9.0%, whereas computed tomography-detected cavitation decreased only modestly (20.4% to 17.7%). Xpert MTB/RIF testing increased from 41.5% to 77.0%, bronchoscopic yield from 71.2% to 81.8%, and treatment success from 59.7% to 70.0%, whereas mortality decreased from 10.0% to 7.3% and isoniazid resistance from 9.1% to 6.5% (all P for trend ≤0.011). CONCLUSION: TB care in South Korea increasingly involves older and medically complex patients. Pulmonary TB became less recognizable on initial chest radiography, whereas molecular testing, bronchoscopic confirmation, and treatment outcomes improved. These findings support public-private mix-based quality monitoring, integrated care for vulnerable patients, and diagnostic pathways adapted to less typical radiographic presentations.