Rao 1997.

Study characteristics
Patient sampling	Consecutive patients with suspected appendicitis were referred for CT examination of the appendix. Patients were referred from the Emergency Department or from private surgeons' offices. It is unclear whether all patients with clinically suspected appendicitis had CT. Pregnant women and patients younger than 6 years were excluded. Women with gynaecological abnormalities detected by pelvic ultrasonography were ineligible for the study Recruitment period: October 1995 to March 1996
Patient characteristics and setting	Age range: 6 to 84 years. The proportion of patients younger than 15 years is not reported. 54% women Department of Radiology, Boston, Massachusetts, USA. Single‐centre study Disease spectrum: unclear
Index tests	Single‐slice helical CT of the lower abdomen with oral and rectal contrast enhancement (HiSpeed Advantage, General Electric). Slice thickness and slice interval: 5 mm. Voltage and mAs product: not stated. 4 patients with a potential contraindication to rectal contrast received only oral contrast enhancement
Target condition and reference standard(s)	Appendicitis. Intraoperative findings or histological examination in patients who had surgery with or without appendectomy. Follow‐up in patients who did not have surgery. Follow‐up consisted of at least 1 outpatient clinic visit and phone calls approximately 1 week, 1 month, and 3 months after the CT‐scan
Flow and timing	103 patients were referred for CT examination. 2 patients declined to participate. Of the 101 included patients, 61 had surgery and 56 had appendicitis. Clinical follow‐up was uneventful in 38 patients. 1 patient was lost to follow‐up, and the final diagnosis was unclear in another. Both of these patients were excluded from the analyses, which included 99 patients
Comparative
Criteria for CT diagnosis of appendicitis	Appendix diameter > 6 mm with periappendiceal inflammatory changes such as fat stranding, fluid collection, phlegmon, or extraluminal gas
Assessors of the CT‐scan	1 board certified radiologist
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?	Yes
Does the study population represent an unselected sample of adults with suspected appendicitis?	No
		Unclear	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?	Yes
		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	Low
DOMAIN 4: Flow and Timing
Did all patients receive a reference standard?	Yes
Did all patients receive the same reference standard?	No
Did all patients with a positive CT‐scan have surgery?	No
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