Patients	Patients or specimens of any age presumed to have resistance to any of the second-line TB drugs and those with confirmed MDR-TB
Prior testing	Patients who received MTBDRsl testing will first have received smear microscopy or culture (if smear-negative) or both for the detection of TB and phenotypic or genotypic DST for resistance to first-line TB drugs
Settings	Intermediate or central level laboratories
Index (new) test	MTBDRsl assay
Reference standard	Culture-based DST
Studies	Cross-sectional and case control studies in which cases and controls were sampled from the same patient population
A. MTBDRsl for XDR-TB by indirect testing
Prevalence	Sensitivity (95% CI) 70.9% (42.9 to 88.8)	Specificity (95% CI) 98.8% (96.1 to 99.6)	Number of participants (studies)	Quality of the evidence (GRADE)*
8%	A diagnostic test does not always accurately detect all of the people who actually have the disease or condition in question. 80 people (out of 1000 people) have (as yet undetected) XDR-TB. Of the 1000 people who take the MTBDRsl test, 57 people will be correctly identified as having XDR-TB (TPs). However, 23 people with XDR-TB will remain undetected; their "negative" test results will be incorrect (FNs).	A diagnostic test does not always accurately identify all of the people who do not have the disease or condition in question. 920 people (out of 1000 people) do not have XDR-TB. Of the 1000 people who take the MTBDRsl test, 909 of these people will be correctly identified as not having XDR-TB (TNs). However, 11 people will be incorrectly identified; their "positive" test results will suggest they have XDR-TB (FPs).	880 (8 studies)	Quality of the evidence indicates how likely it is that the accuracy of the test will be substantially different from what the research found. Low ⊕⊕оо
11%	110 people (out of 1000 people) have (as yet undetected) XDR-TB. Of the 1000 people who take the MTBDRsl test, 78 people will be correctly identified as having XDR-TB (TPs). However, 32 people with XDR-TB will remain undetected; their "negative" test results will be incorrect (FNs).	890 people (out of 1000 people) do not have XDR-TB. Of the 1000 people who take the MTBDRsl test, 879 of these people will be correctly identified as not having XDR-TB (TNs). However, 11 people will be incorrectly identified; their "positive" test results will suggest they have XDR-TB (FPs).
B. MTBDRsl for XDR-TB, by direct testing, 644 participants (3 studies). There was considerable heterogeneity in accuracy estimates and we did not perform a meta-analysis

*We deducted one point for limitations and one point for imprecision (considering the wide 95% CI for pooled sensitivity). We did not deduct points for indirectness; however we consider sensitivity and specificity to be surrogates for patient-important outcomes and high accuracy does not mean that patients will get better.