The details of the Hinchliffe study
| Methods | Study type: single-centre, randomised controlled trial, open label, intention-to-treat Study aim: to test the hypothesis that EVAR can reduce the perioperative mortality of ruptured AAA, compared with open repair Country: England Setting: hospital | |
| Participants | Number randomised: total n=32 (eEVAR n=15; open repair n=17) Age (median years (IQR)): eEVAR=74 years (68.8–79.5); open repair=80 years (73. 8–83.8) Gender (M/F): eEVAR=11/4; open repair=13/4 Inclusion criteria: all patients admitted with clinically suspected or radiologically confirmed rupture of an infrarenal abdominal aortic aneurysm that, in the opinion of the duty consultant vascular surgeon would normally be treated with open repair Exclusion criteria: no endovascular team available; full selection of emergency stent grafts not available; age <50 years; inability to give verbal or written consent; unconscious patient; allergy to radiological contrast, stainless steel or polyester; severe comorbidity that would preclude intensive care treatment following open repair; previous endovascular AAA repair; women of childbearing potential not taking contraception; pregnant and lactating women eEVAR anatomical suitability (exclusion criteria): absolute contraindications: no evidence on aneurysm rupture, juxtarenal aneurysm, neck diameter >32 mm, external iliac artery diameter >6 mm; relative contraindications: proximal neck length <10 mm, excessive thrombus in the proximal neck, common iliac artery length <25 mm, heavily calcified iliac arteries | |
| Interventions | eEVAR description: those with a diagnostic CT were transferred directly to operating theatre, and those without first had a CT scan to determine aortic measurement; performed in dedicated vascular operating theatre using a Siremobil 2000 image intensifier, with digital subtraction angiography facilities; most patients heparinised; two-piece aortouniiliac stent graft made with Gianturco stents with uncovered suprarenal component; occluding device used in contralateral common iliac artery; after deployment of stent graft, a femoro-femoral crossover graft was performed Open repair description: after randomisation to open repair, patients were transferred directly to the operating theatre, according to local practice; performed transperitoneally either by midline or transverse incisions; aorta clamped below renal arteries; patients no heparinised; inlay technique was used and grafts were gelatin-coated polyester | |
| Outcomes | Perioperative mortality, defined as 30-day or in-hospital | |
| Notes | ‘Patients were deemed suitable for EVAR if, in the opinion of the operating surgeon, they could perform the repair’; participants recruited September 2002 to December 2004; five surgeons on unit, required that surgeon and team available had sufficient expertise to offer EVAR, if not, conventional open repair was offered; unstable patients that might be disadvantaged by delay incurred by CT scan could, at the surgeon's discretion, not be randomised and taken directly for open repair | |
| Risk of bias | ||
| Bias | Authors’ judgement | Support for judgement |
| Random sequence generation (selection bias | Unclear risk | ‘Randomisation was then performed from sealed opaque envelopes kept in the Accident and Emergency Department’. Unclear how randomisation sequence was generated |
| Allocation concealment (selection bias) | Low risk | ‘Randomisation was then performed from sealed opaque envelopes kept in the Accident and Emergency Department’ |
| Blinding of participants and personnel (performance bias); all outcomes | Low risk | Study was unblinded, due to nature of intervention but unlikely to influence outcomes. ‘The surgeons were blinded to the dimensions of patient's aorta until randomisation had taken place’ to avoid bias |
| Blinding of outcome assessment (detection bias); all outcomes | Low risk | Not possible to blind team regarding allocation group, but unlikely to influence outcome measures |
| Incomplete outcome data (attrition bias); all outcomes | Low risk | All patients accounted for; crossover patients accounted for; similar dropout rates and reasons between treatment groups |
| Selective reporting (reporting bias) | Low risk | Most of the protocol outlined in the text; all relevant outcomes reported; with the exception of mortality, outcomes are not well described in the methods |
| Other bias | Unclear risk | Underpowered study: 32 of the required 100 patients recruited |
AAA, abdominal aortic aneurysm; eEVAR, emergency endovascular aneurysm repair; F, female; M, male.