Treatment outcomes and survival based on drug resistance patterns in multidrug-resistant tuberculosis.

RATIONALE: Few large-scale studies have investigated multidrug-resistant tuberculosis (MDR-TB) treatment outcomes relative to drug-resistance patterns. OBJECTIVES: To assess the impact of additional drug resistances on treatment outcomes and long-term survival in a large HIV-negative MDR-TB cohort. METHODS: Treatment outcomes and long-term survival of patients with MDR-TB newly diagnosed or retreated in 2000 to 2002 were retrospectively analyzed based on drug-resistance patterns after 5-8 years of follow-up. MEASUREMENTS AND MAIN RESULTS: Of 1,407 patients with MDR-TB, 75 (5.3%) had extensively drug-resistant TB (XDR-TB(re)) by the revised definition; 159 (11.3%) had ofloxacin-resistant pre-XDR-TB (pre-XDR-TB(o)); and 117 (8.3%) had second-line injectable drug (SLID)-resistant pre-XDR-TB (pre-XDR-TB(s)). Patients with XDR-TB(re) showed the lowest treatment success rate (29.3%) and the poorest long-term survival, and XDR-TB(re) was more strongly associated with long-term mortality than XDR-TB as originally defined (hazards ratio [HR], 3.15; 95% confidence interval [CI], 2.06-4.83; P < 0.001 vs. HR, 2.15; 95% CI, 1.49-3.09; P < 0.001). Patients with either form of pre-XDR-TB showed poorer cumulative survival than those with ofloxacin-susceptible/SLID-susceptible MDR-TB (P < 0.05 for each comparison). Although streptomycin susceptibility did not affect the treatment outcomes of patients with pre-XDR-TB, streptomycin-resistant pre-XDR-TB was more strongly associated with long-term mortality than ofloxacin-susceptible/SLID-susceptible MDR-TB (HR, 2.17; 95% CI, 1.22-3.84; P < 0.008 for pre-XDR-TB(o); and HR, 2.69; 95% CI, 1.40-5.16; P = 0.003 for pre-XDR-TB(s)). CONCLUSIONS: The revised XDR-TB definition is appropriate for defining patients with MDR-TB with the poorest outcomes. Both pre-XDR-TB(o) and pre-XDR-TB(s) were independently associated with poor long-term survival in patients with MDR-TB. SM susceptibility was linked to better survival in patients with pre-XDR-TB.

Treatment outcomes and long-term survival in patients with extensively drug-resistant tuberculosis.

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.