Rationale: The increasing worldwide incidence of extensively drug-resistant tuberculosis (XDR-TB) has emerged as a threat to public health and tuberculosis (TB) control. Treatment outcomes have varied among studies, and data on long-term survival are still scarce.
Objectives: To retrospectively assess the burden, clinical characteristics, treatment outcomes, and long-term survival rate of patients with XDR-TB in a cohort of patients with HIV-negative multidrug-resistant tuberculosis (MDR-TB) in South Korea.
Methods: Medical records were reviewed of patients newly diagnosed with or retreated for MDR-TB from 2000 to 2002. The cohort was monitored for 3 to 7 years after the initiation of treatment. Initial treatment outcomes and cumulative survival rates were analyzed, and predictors of treatment success and survival were defined.
Measurements and main results: Of 1,407 patients with MDR-TB 75 (5.3%) had XDR-TB at treatment initiation. The default rate was high (453/1,407; 32%), and patients with XDR-TB had lower treatment success (29.3 vs. 46.2%; P = 0.004) and higher all-cause (49.3 vs. 19.4%; P < 0.001) and TB-related disease mortality (41.3 vs. 11.8%; P < 0.001) than other patients with MDR-TB. The presence of XDR-TB significantly affected treatment success (odds ratio, 0.23; 95% confidence interval [CI], 0.08-0.64; P = 0.005), all-cause mortality (hazards ratio, 3.25; 95% CI, 1.91-5.53; P < 0.001), and TB-related mortality (hazards ratio, 4.45; 95% CI, 2.48-8.00; P < 0.001) on multivariate analyses.
Conclusions: XDR-TB occurred in a substantial proportion of patients with MDR-TB in South Korea, and was the strongest predictor of treatment outcomes and long-term survival in patients with MDR-TB. Adequate TB control policies should be implemented to prevent the further development and spread of drug resistance.