Poor Prognosis Seen in TB Patients With Extensive Drug Resistance

In a retrospective study, researchers assessed the impact of a diagnosis of extensively drug-resistant TB (XDR-TB) on treatment outcomes and long-term survival of mostly HIV-negative South Korean patients with multidrug-resistant TB (MDR-TB).

"Treatment outcomes of [XDR-TB] have varied among studies, and data on long-term survival are still scarce," wrote Dr. Tae Sun Shim of the Asan Medical Center in Seoul and colleagues. The authors reviewed the medical records of 1,407 patients newly diagnosed with or re-treated for MDR-TB during 2000-2002. The study followed these patients for three to seven years after treatment initiation.

Among MDR-TB patients, 75 (5.3 percent) were determined to have XDR-TB at baseline. Compared to MDR-TB patients, those with XDR-TB had lower treatment success (29.3 percent vs. 46.2 percent) and higher all-cause mortality (49.3 percent vs. 19.4 percent) and TB-related mortality (41.3 percent vs. 11.8 percent). In multivariate analysis, XDR-TB decreased the chances of treatment success by 77 percent and increased all-cause mortality by 225 percent and TB-related mortality 345 percent, researchers found.

"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," the study concludes. "Adequate TB control policies should be implemented to prevent the further development and spread of drug resistance."

The study, "Treatment Outcomes and Long-Term Survival in Patients with Extensively Drug-Resistant Tuberculosis," was published in American Journal of Respiratory and Critical Care Medicine (2008;178:1075-1082).

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