IMPROVE.
| Methods | Study type: multicentre, randomised controlled trial, open label, intention‐to‐treat Study aim: to assess whether EVAR versus open repair reduces early mortality for people with suspected RAAA Country: UK and Canada Setting: 30 hospital vascular units and specialist centres |
|
| Participants | Number randomised: total n = 613 (eEVAR n = 316; open repair n = 297) Age (mean years (± SD)): eEVAR = 76.7 (7.4); open repair = 76.7 (7.8) Gender (M/F): eEVAR = 246/70; open repair = 234/63 Inclusion criteria: men and women over the age of 50 years; clinical diagnosis of RAAA or ruptured aorto‐iliac aneurysm, made by a senior trial hospital clinician Exclusion criteria: previous aneurysm repair; rupture of an isolated internal iliac aneurysm, aorto‐caval or aorto‐enteric fistulae; recent anatomical assessment of the aorta; connective tissue disorder; if intervention was considered to be futile eEVAR anatomical suitability requirements: no absolute requirements will be set for the study, but proximal neck morphology with a diameter exceeding 32 mm or a length less than 10 mm may be considered unfavourable, and iliac artery diameters should be in the range of 8 to 22 mm CVD risk factors (n (%)): not given Type of RAAA: "ruptured AAA or ruptured aortoiliac aneurysm" |
|
| Interventions | eEVAR description: endovascular supracoeliac aortic balloon occlusion will be used to support less stable patients; most interventions performed with aorto‐uni‐iliac graft, but some participants received bifurcated grafts, with subsequent femoro‐femoral crossover graft with contralateral iliac occlusion; control of aorta achieved using local/region anaesthesia, with general anaesthesia used later in procedure if necessary Open‐repair description: CT scan is optional; aneurysms repaired by cross‐clamping the proximal aorta and inserting a prosthetic inlay graft; performed under general anaesthesia | |
| Outcomes | 30‐day mortality, 24‐hour and in‐hospital mortality, costs, re‐interventions at primary admission time and place of discharge, cost‐effectiveness, and mortality at 12 months | |
| Notes | Participants recruited September 2009 to July 2013; flow diagram shows 623 randomised, but 10 were excluded after data monitoring committee reviewed participants, 613 used in analysis; only 275 (87%) of EVAR and 261 (88%) of open repair had confirmed RAAA. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | "An independent contractor provided telephone randomisation, with computer generated assignation of patients in a 1:1 ratio, using variable block size and stratified by centre." |
| Allocation concealment (selection bias) | Low risk | "An independent contractor provided telephone randomisation, with computer generated assignation of patients ..." |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | It was not possible to blind the surgical team, but this was unlikely to influence outcomes. |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Data verification performed centrally at the trial core laboratory; it was unclear if there was blinding, but this was unlikely to influence outcomes. |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | All participants accounted for, with both treatment groups having similar dropout rates/reasons for dropouts. |
| Selective reporting (reporting bias) | Low risk | All pre‐described outcomes reported on. |
| Other bias | Low risk | None |
AAA: abdominal aortic aneurysm CI: confidence interval CT: computed tomography CTA: computed tomography angiography CVD: cardiovascular disease eEVAR: emergency endovascular aneurysm repair EVAR: endovascular aneurysm repair ICU: intensive care unit IQR: interquartile range RAAA: ruptured abdominal aortic aneurysm SD: standard deviation