Stacher 1999.

Study characteristics
Patient sampling	Adult patients (> 18 years) presented with suspected appendicitis between December 1997 and December 1998. It is unclear whether all patients who had an appendectomy during the study period also had a CT‐scan. Pregnant and breastfeeding women were excluded
Patient characteristics and setting	Mean age: 42 years. 41% women. Pregnant or nursing women and patients younger than 18 years were excluded Clinical setting unclear. Austria. Single‐centre study Disease spectrum: unclear
Index tests	Unenhanced helical CT of the lower abdomen (Somatom Plus 4, Siemens). Slice thickness: 5 mm. Slice interval: 4 mm. Voltage: 140 kV. mAs product: 92.5 mAs. Multi‐planar reconstructions were used if axial images were insufficient for definitive diagnosis
Target condition and reference standard(s)	Appendicitis. Of the 56 included patients, 32 had surgery with histological assessment of the removed appendix, and 24 had follow‐up. Follow‐up was performed after 2 months, but otherwise the concept of follow‐up is not stated
Flow and timing	56 patients were included and analysed
Comparative
Criteria for CT diagnosis of appendicitis	Positive CT findings were defined as a combination of the following features: appendix diameter > 6 mm; and periappendiceal fat stranding
Assessors of the CT‐scan	3 experienced radiologists. Non‐paired assessments were performed, but consensus assessments were used if 1 radiologist was in doubt about the diagnosis
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?	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?	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
		Low	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?	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