Balthazar 1991.

Study characteristics
Patient sampling	Consecutive patients referred for abdominal CT due to atypical symptoms and signs of appendicitis (lower abdominal pain and tenderness, but no nausea, vomiting, low‐grade fever, or leukocytosis). No exclusion criteria reported
Patient characteristics and setting	Age range (mean): 9 to 87 years (42). The proportion of patients younger than 15 years is not reported. 48% women Department of Radiology, Philadelphia, Pennsylvania, USA. Single‐centre study Disease spectrum: intermediate suspicion of appendicitis
Index tests	Non‐helical CT of the entire abdomen with oral and intravenous contrast enhancement (9800, General Electric Medical Systems). Slice thickness and slice interval: 5 to 8 mm. Voltage and mAs product: not stated
Target condition and reference standard(s)	Appendicitis. Histological examination was performed in patients who had an appendectomy. Discharge diagnosis and follow‐up were provided for patients who did not have surgery. It is not stated how follow‐up was performed
Flow and timing	100 patients were included. Surgery with appendectomy was performed in 74 patients; 64 had appendicitis confirmed histologically. No account is reported on completeness and outcomes of follow‐up in the 36 patients who did not have surgery
Comparative
Criteria for CT diagnosis of appendicitis	Appendix diameter > 3 mm, periappendiceal inflammatory changes, appendix wall hyperenhancement, thickened appendix wall, abscess or phlegmon in the right iliac fossa, appendicolith
Assessors of the CT‐scan	Not stated
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Did the study avoid inappropriate exclusions?	Unclear
Does the study population represent an unselected sample of adults with suspected appendicitis?	Unclear
		Unclear	Unclear
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?	Unclear
Is the index test described in sufficient detail to permit its replication?	No
Was the analysis based on the initial evaluation of the CT‐scan by the radiologist on call?	Yes
		Unclear	High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		Unclear	Low
DOMAIN 4: Flow and Timing
Did all patients receive a reference standard?	Unclear
Did all patients receive the same reference standard?	No
Did all patients with a positive CT‐scan have surgery?	Yes
Did all patients with a negative CT‐scan have clinical follow‐up?	No
Was the choice of reference standard independent of the result of the index test?	No
Were all patients included in the analyses?	Yes
		High