Eliasziw 1995.

Study characteristics
Patient Sampling	The study used data collected from the first 3 years of NASCET; 1360 patients were recruited from 50 academic centers across North America. A total of 1011 patients had complete ultrasonographic data. Exclusion criteria: data incomplete or unavailable, ischemic event attributable to a cardiac source of embolism, age over 80 years, presence of significant intracranial vascular disease, and life‐threatening or other disabling conditions
Patient characteristics and setting	All patients were symptomatic; other characteristics of the included patients were not described.
Index tests	DUS Image production: the ultrasound device was not specified; the vast majority of the transducers used were in the 5‐MHz range. Contrast: No Criteria used to determine grade of stenosis: described in Appendix 9
Target condition and reference standard(s)	Reference standard: DSA Target condition: Symptomatic patients with severe (70% to 99%) carotid stenoses Criteria used to determine grade of stenosis: NASCET criteria Complications: stroke rate from angiography was 0.78%
Flow and timing	Ultrasonography was performed concurrently to the angiogram.
Comparative
Methods	Study design: Cross‐sectional study; participants consecutively enrolled Study location: Multicenter in North America Year and language of publication: Published in 1995 in English Study period: from January 1988 through February 1991 Participants enrolled: 1011 patients Carotids included in analyses: 1011 carotids
Notes	Ultrasonography was performed concurrently to the angiogram but was not used in the decision‐making process for entering patients into the study.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Yes
Could the selection of patients have introduced bias?		Low risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
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
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
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?	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Low risk