sentences:  XDR-TB is associated with a much higher mortality rate than MDR-TB, because of a reduced number of effective treatment options.A 2008 study in the Tomsk oblast of Russia, reported that 14 out of 29 (48.3%) patients with XDR-TB successfully completed treatment.In 2018, the WHO reported that the treatment success rate for XDR-TB was 34% for the 2015 cohort, compared to 55% for MDR/RR-TB (2015 cohort), 77% for HIV-associated TB (2016 cohort), and 82% for TB (2016 cohort).