Aspelund 2014.

Study characteristics
Patient Sampling	Type of study: retrospective
Patient characteristics and setting	Sample size: 397 Females: unclear Mean age: unclear Inclusion criteria: Paediatric patients (< 18 years) with suspected appendicitis and equivocal ultrasound Exclusion criteria: Over 18 years Imaging performed to exclude other disease Initial imaging elsewhere Setting: university hospital, USA, 2008 to 2012
Index tests	Index test: MRI Index test criteria for positive diagnosis: see Appendix 5
Target condition and reference standard(s)	Target condition: appendicitis Reference standard: histology or follow‐up
Flow and timing	Type and length of follow‐up: telephone survey Number of participants who were excluded from the analysis: 237/397 participants not followed up by telephone; these participants were still included in analysis.
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?	No
Avoids Inappropriate Exclusion	No
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	No
If a threshold was used, was it pre‐specified?	Unclear
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Unclear
DOMAIN 3: Reference Standard
Are the reference standards (histo or F/U) likely to correctly classify the target condition?	Yes
Were the reference standard (histo or F/U) results interpreted without knowledge of the results of the index test	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Did all patients receive the same reference standard?	No
Were all patients included in the analysis?	Yes
>95% histo or F/U	No
all +ve MRI had surgery or F/U	Yes
all ‐ve MRI had surgery or F/U	No
choice of reference standard independent of MRI	No
Could the patient flow have introduced bias?		High risk