Pakaneh 2008.

Study characteristics
Patient sampling	Patients with a clinical diagnosis of appendicitis were candidates for appendectomy. Patients with long‐lasting abdominal pain, patients with suspected perforated appendix, and patients with unstable haemodynamics were excluded Recruitment period: May to July 2006
Patient characteristics and setting	Age range (median): 13 to 76 years (25). 26% women Department of Surgery, Imam Khomeini Hospital, Tehran, Iran. Single‐centre study Disease spectrum: high suspicion of appendicitis
Index tests	Unenhanced helical CT of the lower abdomen. Slice thickness: 5 mm. Slice interval, voltage, and mAs product: not stated. Manufacturer of CT‐scanner, model name, and slice number: not stated
Target condition and reference standard(s)	Appendicitis. All patients had surgery with appendectomy and histological assessment of the removed appendix as the reference test
Flow and timing	50 patients were included; all had surgery, and 42 had appendicitis confirmed histologically
Comparative
Criteria for CT diagnosis of appendicitis	Positive CT findings were defined as presence of at least 1 of the following: appendix diameter > 6 mm, periappendiceal fat stranding, appendicolith, periappendiceal free fluid, flegmone or abscess
Assessors of the CT‐scan
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
Did the study avoid inappropriate exclusions?	Yes
Does the study population represent an unselected sample of adults with suspected appendicitis?	No
		Low	High
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
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?	Unclear
		Low	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
		Unclear	High
DOMAIN 4: Flow and Timing
Did all patients receive a reference standard?	Yes
Did all patients receive the same reference standard?	Yes
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?	Yes
Were all patients included in the analyses?	Yes
		Low