Balcells 2012

Study characteristics
Patient sampling	Cross‐sectional design with consecutive enrolment of patients, prospective data collection
Patient characteristics and setting	Presenting signs and symptoms: Patients who fulfilled at least one of the following criteria: cough (> 10 days), bloody sputum, pneumonia unresponsive to previous antibiotics, fever (> 10 days), abnormal CXR or weight loss Age: Mean 37.4 years (range 19 to 65) Sex, female: 20.6% HIV infection: 100% History of TB: 11.8% Sample size: 160 Clinical setting: Five hospitals and their respective HIV clinics Laboratory level: Intermediate Country: Chile World Bank Income Classification: Middle‐income TB incidence rate: 18 per 100,000 MDR‐TB prevalence: Percent MDR‐TB among new TB cases = 0.7% (Source: Nationwide survey 2001) and among retreatment cases = 3.2% (Source: Nationwide surveillance 2011) Proportion of TB cases in the study: 7.5%
Index tests	Index: Xpert MTB/RIF assay Specimen condition: Fresh Specimen preparation: Processed Xpert MTB/RIF version: 2 and 3
Target condition and reference standard(s)	Target condition: Pulmonary TB Reference standard for pulmonary TB: Löwenstein‐Jensen culture and MGIT 960 Target condition: Rifampicin resistance Reference standard for rifampicin resistance: Proportion method on Löwenstein‐Jensen media
Flow and timing
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
		Low	Low
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
		Low	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results for TB detection interpreted without knowledge of the results of the index test?	Yes
Were the reference standard results for rifampicin resistance detection interpreted without knowledge of the results of the index test?	Yes
		Low	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
		Low