Scott 2015.

Study characteristics
Patient sampling	Patients admitted with suspected appendicitis were referred for CT. The referral was provided at the discretion of the clinical team. Recruitment period: August 2012 to July 2013. Observational study ‐ no exclusion criteria were applied
Patient characteristics and setting	Age range (median): 13 to 93 (46). 1 patient was younger than 15 years of age. 58% women. The proportion of patients younger than 15 years is not stated Department of General Surgery in West Middlesex, England. Single‐centre study Disease spectrum: unclear
Index tests	16‐slice or 128‐slice CT of the entire abdomen with oral contrast material (Toshiba, Aquillion 16 or Aquillion 128). Slice thickness: 1 mm. Slice interval: 1 mm. Voltage: 120 kV. mAs product: not stated
Target condition and reference standard(s)	Appendicitis. Histological examination of the removed appendix was performed in patients who had an appendectomy. Patients were classified as not having appendicitis if they did not require surgery, if a macroscopically normal appendix was found intraoperatively, or if the removed appendix was without a transmural neutrophilic infiltrate on histological examination. Follow‐up for patients who did not have surgery consisted of checking for readmission for a minimum of 30 days after discharge
Flow and timing	476 patients with suspected appendicitis were included. Among the 86 patients referred for CT, 39 had surgery and appendicitis was confirmed histologically in 34. Analyses include all 86 patients who had CT
Comparative
Criteria for CT diagnosis of appendicitis	Radiologists were unaware of the study and followed standard practice when assessing the CT‐scan
Assessors of the CT‐scan	Radiologist on call
Notes	The primary aim of this study was to evaluate the accuracy of the Appendicitis Inflammatory Response Score in patients with suspected appendicitis. Only a subset of patients were referred for CT as part of the evaluation Additional information about this study was kindly provided by Alasdair Scott
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?	No
		High	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?	Yes
Was the analysis based on the initial evaluation of the CT‐scan by the radiologist on call?	Yes
		High	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	No
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		High	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?	Unclear
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