Rao 1998.

Study characteristics
Patient sampling	Patients with suspected appendicitis were referred for CT examination of the appendix. Patients were referred from the Emergency Department or from private surgeons' offices. 100 of 117 patients admitted with a principal diagnosis of appendicitis were referred for CT. It is unclear whether all patients with clinically suspected appendicitis had CT. Pregnant women, patients younger than 6 years, and patients with a clinical contraindication to contrast material administered through the colon were excluded Recruitment period: July 1996 to November 1996
Patient characteristics and setting	Age range (mean): 6 to 75 (28) years (27% were paediatric patients). 57% women Department of Radiology, Boston, Massachusetts, USA. Single‐centre study Disease spectrum: any suspicion of appendicitis
Index tests	Single‐slice helical CT of the lower abdomen with rectal contrast enhancement (HiSpeed Advantage, General Electric Medical Systems). Slice thickness and slice interval: 5 mm. Voltage and mAs product: not stated
Target condition and reference standard(s)	Appendicitis. Intraoperative findings or histological examination was documented for patients who had surgery with or without appendectomy. Follow‐up was provided for patients who did not have surgery. Follow‐up included outpatient clinic visits and phone calls approximately 1 week and 2 months after CT‐scan
Flow and timing	100 patients were included. No ineligible patients were referred for CT examination, and all referred patients agreed to participate. Surgery was performed in 59 patients, and 53 had appendicitis. Follow‐up was performed in 41 patients ‐ none were lost to follow‐up
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. Appendicitis was diagnosed in cases with non‐visualisation of the appendix only in the presence of specific CT signs of appendicitis, such as an appendicolith, focal caecal apical thickening, arrow head sign, or caecal bar sign. The appendix was considered normal if the appendiceal lumen filled completely with contrast material, air, or both, regardless of appendix diameter
Assessors of the CT‐scan	3 board certified radiologists
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
Did the study avoid inappropriate exclusions?	Yes
Does the study population represent an unselected sample of adults with suspected appendicitis?	Unclear
		High	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?	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