Silverstein 1998.

Study characteristics
Patient sampling	Type of study: prospective. Consecutive or random sample: consecutive.
Patient characteristics and setting	Sample size: 262. Females: 206 (78.6%). Age: 47 years. Presentation: Inclusion criteria: People undergoing cholecystectomy with ≥ 1 of the following features Abnormal liver function tests. History of obstructive jaundice or pancreatitis. Common bile duct diameter > 6 mm in calibre on ultrasound. Setting: Department of Surgery, USA.
Index tests	Index test: ultrasound. Technical specifications: not stated. Performed by: not stated. Criteria for positive diagnosis: common bile duct diameter > 6 mm. Index test: bilirubin. Technical specifications: not applicable. Performed by: not applicable. Criteria for positive diagnosis: cut‐offs used to define test positivity were > 22.23 μmol/L and > twice the normal limit. Index test: alkaline phosphatase. Technical specifications: not applicable. Performed by: not applicable. Criteria for positive diagnosis: cut‐offs used to define test positivity were > 125 IU/L and > twice the normal limit.
Target condition and reference standard(s)	Target condition: common bile duct stones. Reference standard: endoscopic or surgical extraction of stones in people with positive intraoperative cholangiogram and clinical follow‐up of minimum 2 years in other people (participants underwent selective cholangiogram). Technical specifications: not applicable. Performed by: endoscopists, surgeons, and clinicians. Criteria for positive diagnosis: endoscopic or surgical extraction of stones in people with positive intraoperative cholangiogram and clinical follow‐up of minimum 2 years in other people (participants underwent selective cholangiogram).
Flow and timing	Number of indeterminates for whom the results of reference standard was available: not stated. Number of participants who were excluded from the analysis: not stated.
Comparative
Notes	Attempted to contact the authors in June 2013. Received no replies.
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?	Unclear
If a threshold was used, was it pre‐specified?	Yes
		High	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		High	High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	Yes
		High