Katz 2004.

Study characteristics
Patient sampling	Type of study: prospective study. Consecutive or random sample: consecutive participants.
Patient characteristics and setting	Sample size: 41. Females: not stated. Age: not stated. Presentation: Inclusion criteria: People with suspicion of biliary stone disease on the basis of dilated common bile duct > 10 mm, abnormal liver function tests, or pancreatitis. Setting: Department of Surgery, USA.
Index tests	Index test: endoscopic retrograde cholangiography. Further details: Technical specifications: not stated. Performed by: endoscopist. Criteria for positive diagnosis: not stated.
Target condition and reference standard(s)	Target condition: common bile duct stones. Reference standard: endoscopic extraction of bile duct stones in people with positive endoscopic retrograde cholangiography and follow‐up for at least 1 year for people with negative endoscopic retrograde cholangiography. Further details: Technical specifications: not applicable. Performed by: endoscopists and surgeons. Criteria for positive diagnosis: presence of stones during endoscopic clearance and clinical follow‐up with negative endoscopic retrograde cholangiography.
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 ERCP
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
		High	High
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