Nagre 2011.

Clinical features and settings	People who received EVAR for AAA. Type of stents received: not reported. Aneurysm diameter: not reported. Setting: vascular surgery department.
Participants	445 participants; 84.2% men; 91.2% white people; mean (± SD) age: 71.4 ± 8.5 years; range: 38‐93 years. Comorbidities: smoking (91%), coronary artery disease (51%), hypertension (64%), hyperlipidaemia (43%), stroke (10%), diabetes mellitus (14%), chronic obstructive pulmonary disease (21%), and end‐stage renal disease on dialysis (3%). Geography: USA. Recruitment period: October 1999 to June 2009.
Study design	Retrospective study. Review of prospectively maintained database designed to capture all EVAR procedures performed between October 1999 and June 2009. Participants routinely evaluated with CT and DUS imaging within 30 days after procedure and intermittently at 6‐ to 12‐month intervals after treatment.
Target condition and reference standard(s)	Target condition: endoleak. Definition of endoleak: continuing blood flow around graft into aneurysm sac, thereby exposing participants to risk of rupture. "Endoleaks that were identified within 30 days of follow‐up were classified as early endoleaks, whereas those detected after 30 days were classified as late." Endoleak (absolute n): 154. Prevalence of endoleak: 27.5% (100/561). Reference standard: CTA. Image acquisition: both contrast and non‐contrast images obtained by performing helical scans from diaphragm to upper thigh using a thin section CTA protocol. Non‐ionic IV contrast material administered. 3D reconstructions performed. Delay in scan determined by bolus tracking. CTA obtained in people with normal renal function and people on regular haemodialysis. Type of CT scanner: GE LightSpeed 16 CT scanner (General Electric Medical Systems, Milwaukee, WI, USA). Use of contrast: yes, non‐ionic IV contrast.
Index and comparator tests	Index test: CDUS. Image production: abdominal aorta and iliac arteries investigated in transverse, and antero‐posterior images obtained. Type of US: Sequoia 512 Acuson Sonography System (Siemens Medical Solutions, Mountain View, CA, USA). Use of contrast: no. Operator: 1 registered vascular technician.
Follow‐up	Missing data or loss to follow‐up unclear.
Notes	"DUS imaging and CTA were evaluated with attention toward maximum aneurysm diameter, patency of graft, and presence of an endoleak. Maximum aneurysm diameter was the diameter measured in the anterior‐posterior axis and in transverse plane. CTA or DUS was considered significant when a change in size by > 5 mm from the first follow‐up after surgery was noted. Similarly, an increase in size by > 5 mm from the first visit imaging was investigated more thoroughly for possible re‐intervention." "Contrast material was not used in 49 CT scans, leaving 561 encounters for comparing contrast CT imaging with DUS results." "Our initial protocol included CTA and DUS at the initial visit, and most were further followed up with CTA."
Table of Methodological Quality
Item	Authors' judgement	Description
Representative spectrum? All tests	Unclear	Sample derived from retrospective review of database in which data of people with AAA who received stent did not necessarily receive concomitant US and CTA. Participants included were those who had both tests available during follow‐up. ("A total of 1,062 EVARs were performed in 992 patients during this period. Medical records, vascular database records, and follow‐up images of these patients were reviewed in detail. National death indices were also reviewed for patients who were lost to follow‐up. A total of 3,120 postsurgical imaging encounters were recorded through the surveillance protocol. Of these 3,120 encounters, 1,729 were DUS encounters (1.86 per patient), whereas 2,001 were CTA scans (2.16 per patient), with 610 of these encounters recording a CTA and DUS at the same visit. Contrast material was not used in 49 CT scans, leaving 561 encounters in 455 patients, for comparing CTA imaging with DUS findings.")
Acceptable reference standard? All tests	Unclear	CT scan with contrast agents. No mention of expert who read and interpreted images provided.
Acceptable delay between tests? All tests	Yes	"Both studies should be recorded within 7 days of each other."
Partial verification avoided? All tests	Yes	All participants accounted for and results of reference standard reported for all.
Differential verification avoided? All tests	Yes	All participants who received index test subjected to same reference standard.
Incorporation avoided? All tests	Yes	Index test not part of reference standard.
Reference standard results blinded? All tests	Unclear	Not reported.
Index test results blinded? All tests	Unclear	Not reported.
Relevant clinical information? All tests	Yes	Yes.
Uninterpretable results reported? All tests	Yes	"Of these 3,120 encounters, 610 had both CT scan and ultrasound at the same visit. Contrast material was not used in 49 CT scans, leaving 561 encounters for comparing contrast CT imaging with DUS results. CT and DUS detection of endoleaks correlated in 442 encounters. Discrepancies occurred in 119 encounters as follows: CT scan only endoleak in 17.8% (tot: 100; type I: 6, type II: 91 and type III: 3) and DUS only endoleak in 3.4% (N 19; type II: 19) encounters. Of these 119 encounters, 99 did not require secondary interventions. Eventually, 15 patients required intervention after 20 discrepancy encounters: 11 patients continued with the surveillance protocol through CT or DUS imaging, whereas four were observed by CT imaging only. Considering these 11 patients, DUS eventually detected an endoleak on subsequent visits in five patients, DUS identified an increase in aneurysm diameter in four patients, and DUS never identified the type II endoleaks in two patients. When the endoleak raised concern or the aneurysm enlarged, we undertook 19 secondary interventions in these 15 patients: vessel embolization (N 8), iliac extenders (N 5), graft relining (N 3), graft explants (N 2), and proximal cuff (N 1)."
Withdrawals explained? All tests	Unclear	"Of these 119 encounters, 99 did not require secondary interventions. Eventually, 15 patients required 19 re‐interventions after 20 discrepancy encounters (3.6%). Eleven patients continued with the surveillance protocol through CTA or DUS imaging, whereas four were followed up by CTA imaging only. One of these 15 patients had a type II endoleak that was missed by CTA and detected on DUS on subsequent follow‐up. Of these 15 patients, 12 were diagnosed with an early endoleak, whereas the remaining three were diagnosed with a late endoleak. There was no rupture, graft migration, limb occlusion, or structural failure in any of these 15 patients. Table III summarizes the secondary interventions in these 119 encounters."