Nationwide coverage of molecular drug susceptibility testing in patients with pulmonary multidrug/rifampicin-resistant tuberculosis in South Korea: a retrospective cohort study (2015-2021)

Background We assessed the coverage of molecular drug susceptibility testing (mDST) among patients with pulmonary multidrug/rifampicin-resistant tuberculosis (MDR/RR-TB) in South Korea and identified factors influencing the lack of mDST implementation. Methods This retrospective study included patients with pulmonary MDR/RR-TB who initiated tuberculosis (TB) treatment between January 2015 and September 2021. Data were obtained from the K-TB-N cohort, an integrated national TB database linking three datasets. We assessed mDST coverage, temporal trends and factors associated with the lack of mDST implementation. mDST was defined as the use of the Xpert MTB/RIF assay or line probe assay (LPA) for isoniazid and rifampicin (first-line LPA). Results In total, 4637 patients were included in the analysis. Of the 4637 patients, 1342 (28.9%) did not undergo mDST; whereas, 3295 (71.1%) underwent mDST. Over the study period, a statistically significant annual increase in mDST coverage was observed, escalating from 49.1% in 2015 to 96.9% in 2021 (p Conclusion Although the increasing mDST coverage is a positive development, further efforts are needed to achieve nationwide and universal implementation, particularly for the Xpert MTB/RIF assay, in South Korea.