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surgery for ruptured abdominal aortic aneurysms

NIHR Signal Endovascular aortic repair (EVAR) surgery more beneficial for ruptured abdominal aortic aneurysms than open repair

Published on 28 August 2018

doi: 10.3310/signal-000638

EVAR surgery to repair a ruptured abdominal aortic aneurysm had a slightly better survival rate after three years than open repair surgery. The survival benefit in this trial wasn’t apparent 30 days after surgery, but those having EVAR did recover more quickly and went home sooner. This NIHR-funded study also found that EVAR is likely to be more cost-effective.

An abdominal aortic aneurysm is a swelling in the main artery that runs from the heart through the abdomen. If it bursts, there is catastrophic bleeding. The traditional treatment is urgent open surgery to repair the rupture. EVAR is a less invasive strategy using a tube of artificial material, placed inside the aorta from an incision in the groin under X-ray control, sealing the leak as well as reinforcing the wall of the vessel.

This study is the first to show that people may have longer-term benefits from a strategy using EVAR where technically suitable for burst aneurysms and open repair if not.

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Why was this study needed?

Ruptured abdominal aortic aneurysms are a common vascular emergency in the older population, causing about 6,000 deaths each year in the UK. About 60% of people survive if they get surgery in time.

Previous research by Sweeting et al. hasn’t shown any clear differences in survival rate at 30 days. The aim of this study was to compare the clinical and cost-effectiveness after three years.

What did this study do?

The IMPROVE trial randomised 613 adults with clinically suspected ruptured aortic aneurysm to either an EVAR strategy group (316 participants), or an open repair group (297 participants). The EVAR strategy group had immediate CT scans followed by EVAR if anatomically possible, or open repair if not. The open repair group had traditional surgery, with optional CT scanning.

The trial took place in 29 vascular centres in the UK and one in Canada. It was primarily designed to measure mortality at 30 days, but follow-up was extended to three years.

Recruitment was difficult. Half of the potential participants did not enter the trial, mostly because they were unfit to have a CT scan or the intervention. Patient and clinician preference also limited participation; however, the pragmatic, real-world design for this trial improves the relevance of the findings to current UK practice.

What did it find?

  • In the EVAR strategy group, 186/316 patients (62%) were anatomically suitable, but EVAR was not performed on 26 of them because of staffed endovascular suites not being immediately available. Overall, 154 patients in this group (49%) had EVAR. In the open repair group, 220/297 (74%) had the allocated procedure. EVAR was performed on 33 people in the open strategy group, mainly because general anaesthetic was considered too risky for them.
  • The mortality rate at 30 days was 35.4% in the EVAR strategy group and 37.4% in the open repair group (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.66 to 1.28).
  • At three years, mortality was 48% in the EVAR strategy group and 56% in the open repair group (OR 0.73, 95% CI 0.53 to 1.00).
  • At three years, there was no difference in quality of life between the groups.
  • The average number of days in hospital for aneurysm-related care (three years after randomisation) was 14.4 days for the EVAR strategy group and 20.5 days in the open repair group. This resulted in a total saving of -£2,607 (95% CI ‑£5,949 to £735) for the EVAR strategy.

What does current guidance say on this issue?

The NICE 2009 technology appraisal on EVAR for the treatment of abdominal aortic aneurysms only recommends the procedure if it is conducted as part of a trial.

NICE is currently developing a guideline on the diagnosis and management of abdominal aortic aneurysm, which is due to be published in November 2018 and will replace the 2009 technology appraisal. The draft guideline says that both EVAR and open repair can be considered for people with a ruptured abdominal aortic aneurysm and that EVAR may provide more benefit for women and men aged over 70.

What are the implications?

Three-year follow-up in the IMPROVE trial shows a survival benefit for the EVAR strategy over open repair. The EVAR strategy is also likely to be more cost-effective, with benefits for both patients and healthcare providers. There are, however, implications for staffing of endovascular services to provide 24-hour availability of EVAR.

An EVAR technique can only be carried out if the aorta and femoral arteries are a certain size and shape, and people with aortic aneurysms often have other health problems which can make EVAR difficult.

This study strengthens the evidence base for the use of EVAR to repair ruptured aneurysms in suitable people.

Citation and Funding

Ulug P, Hinchliffe RJ, Sweeting MJ, et al. Strategy of endovascular versus open repair for patients with clinical diagnosis of ruptured abdominal aortic aneurysm: the IMPROVE RCT. Health Technol Assess. 2018;22(31):1-122.

This project was funded by the National Institute for Health Research HTA programme (project number 07/37/64).

Bibliography

Bjork, M. Endovascular or open repair for ruptured abdominal aortic aneurysm? BMJ. 2017;359:j5170.

IMPROVE Trial Investigators. Comparative clinical effectiveness and cost effectiveness of endovascular strategy v open repair for ruptured abdominal aortic aneurysm: three year results of the IMPROVE randomised trial. BMJ. 2017;359:j4859.

NHS website. Abdominal aortic aneurysm. London: Department of Health; reviewed 2017.

NICE. Abdominal aortic aneurysm: diagnosis and management. In development. London: National Institute for Health and Care Excellence; accessed 31 July 2018.

NICE. Endovascular stent-grafts for the treatment of abdominal aortic aneurysms. TA167. London: National Institute for Health and Care Excellence; 2009.

Sweeting MJ, Balm R, Desgranges P, et  al; Ruptured Aneurysm Trialists. Individual-patient meta-analysis of three randomized trials comparing endovascular versus open repair for ruptured abdominal aortic aneurysm. Br J Surg. 2015;102(10):1229-39.

Why was this study needed?

Ruptured abdominal aortic aneurysms are a common vascular emergency in the older population, causing about 6,000 deaths each year in the UK. About 60% of people survive if they get surgery in time.

Previous research by Sweeting et al. hasn’t shown any clear differences in survival rate at 30 days. The aim of this study was to compare the clinical and cost-effectiveness after three years.

What did this study do?

The IMPROVE trial randomised 613 adults with clinically suspected ruptured aortic aneurysm to either an EVAR strategy group (316 participants), or an open repair group (297 participants). The EVAR strategy group had immediate CT scans followed by EVAR if anatomically possible, or open repair if not. The open repair group had traditional surgery, with optional CT scanning.

The trial took place in 29 vascular centres in the UK and one in Canada. It was primarily designed to measure mortality at 30 days, but follow-up was extended to three years.

Recruitment was difficult. Half of the potential participants did not enter the trial, mostly because they were unfit to have a CT scan or the intervention. Patient and clinician preference also limited participation; however, the pragmatic, real-world design for this trial improves the relevance of the findings to current UK practice.

What did it find?

  • In the EVAR strategy group, 186/316 patients (62%) were anatomically suitable, but EVAR was not performed on 26 of them because of staffed endovascular suites not being immediately available. Overall, 154 patients in this group (49%) had EVAR. In the open repair group, 220/297 (74%) had the allocated procedure. EVAR was performed on 33 people in the open strategy group, mainly because general anaesthetic was considered too risky for them.
  • The mortality rate at 30 days was 35.4% in the EVAR strategy group and 37.4% in the open repair group (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.66 to 1.28).
  • At three years, mortality was 48% in the EVAR strategy group and 56% in the open repair group (OR 0.73, 95% CI 0.53 to 1.00).
  • At three years, there was no difference in quality of life between the groups.
  • The average number of days in hospital for aneurysm-related care (three years after randomisation) was 14.4 days for the EVAR strategy group and 20.5 days in the open repair group. This resulted in a total saving of -£2,607 (95% CI ‑£5,949 to £735) for the EVAR strategy.

What does current guidance say on this issue?

The NICE 2009 technology appraisal on EVAR for the treatment of abdominal aortic aneurysms only recommends the procedure if it is conducted as part of a trial.

NICE is currently developing a guideline on the diagnosis and management of abdominal aortic aneurysm, which is due to be published in November 2018 and will replace the 2009 technology appraisal. The draft guideline says that both EVAR and open repair can be considered for people with a ruptured abdominal aortic aneurysm and that EVAR may provide more benefit for women and men aged over 70.

What are the implications?

Three-year follow-up in the IMPROVE trial shows a survival benefit for the EVAR strategy over open repair. The EVAR strategy is also likely to be more cost-effective, with benefits for both patients and healthcare providers. There are, however, implications for staffing of endovascular services to provide 24-hour availability of EVAR.

An EVAR technique can only be carried out if the aorta and femoral arteries are a certain size and shape, and people with aortic aneurysms often have other health problems which can make EVAR difficult.

This study strengthens the evidence base for the use of EVAR to repair ruptured aneurysms in suitable people.

Citation and Funding

Ulug P, Hinchliffe RJ, Sweeting MJ, et al. Strategy of endovascular versus open repair for patients with clinical diagnosis of ruptured abdominal aortic aneurysm: the IMPROVE RCT. Health Technol Assess. 2018;22(31):1-122.

This project was funded by the National Institute for Health Research HTA programme (project number 07/37/64).

Bibliography

Bjork, M. Endovascular or open repair for ruptured abdominal aortic aneurysm? BMJ. 2017;359:j5170.

IMPROVE Trial Investigators. Comparative clinical effectiveness and cost effectiveness of endovascular strategy v open repair for ruptured abdominal aortic aneurysm: three year results of the IMPROVE randomised trial. BMJ. 2017;359:j4859.

NHS website. Abdominal aortic aneurysm. London: Department of Health; reviewed 2017.

NICE. Abdominal aortic aneurysm: diagnosis and management. In development. London: National Institute for Health and Care Excellence; accessed 31 July 2018.

NICE. Endovascular stent-grafts for the treatment of abdominal aortic aneurysms. TA167. London: National Institute for Health and Care Excellence; 2009.

Sweeting MJ, Balm R, Desgranges P, et  al; Ruptured Aneurysm Trialists. Individual-patient meta-analysis of three randomized trials comparing endovascular versus open repair for ruptured abdominal aortic aneurysm. Br J Surg. 2015;102(10):1229-39.

Strategy of endovascular versus open repair for patients with clinical diagnosis of ruptured abdominal aortic aneurysm: the IMPROVE RCT

Published on 4 June 2018

Ulug P, Hinchliffe R J, Sweeting M J, Gomes M, Thompson M T, Thompson S G, Grieve R J, Ashleigh R, Greenhalgh R M & Powell J T.

Health Technology Assessment Volume 22 Issue 31 , 2018

Background Ruptured abdominal aortic aneurysm (AAA) is a common vascular emergency. The mortality from emergency endovascular repair may be much lower than the 40–50% reported for open surgery. Objective To assess whether or not a strategy of endovascular repair compared with open repair reduces 30-day and mid-term mortality (including costs and cost-effectiveness) among patients with a suspected ruptured AAA. Design Randomised controlled trial, with computer-generated telephone randomisation of participants in a 1 : 1 ratio, using variable block size, stratified by centre and without blinding. Setting Vascular centres in the UK (n = 29) and Canada (n = 1) between 2009 and 2013. Participants A total of 613 eligible participants (480 men) with a ruptured aneurysm, clinically diagnosed at the trial centre. Interventions A total of 316 participants were randomised to the endovascular strategy group (immediate computerised tomography followed by endovascular repair if anatomically suitable or, if not suitable, open repair) and 297 were randomised to the open repair group (computerised tomography optional). Main outcome measures The primary outcome measure was 30-day mortality, with 30-day reinterventions, costs and disposal as early secondary outcome measures. Later outcome measures included 1- and 3-year mortality, reinterventions, quality of life (QoL) and cost-effectiveness. Results The 30-day mortality was 35.4% in the endovascular strategy group and 37.4% in the open repair group [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.66 to 1.28; p = 0.62, and, after adjustment for age, sex and Hardman index, OR 0.94, 95% CI 0.67 to 1.33]. The endovascular strategy appeared to be more effective in women than in men (interaction test p = 0.02). More discharges in the endovascular strategy group (94%) than in the open repair group (77%) were directly to home (p < 0.001). Average 30-day costs were similar between groups, with the mean difference in costs being –£1186 (95% CI –£2997 to £625), favouring the endovascular strategy group. After 1 year, survival and reintervention rates were similar in the two groups, QoL (at both 3 and 12 months) was higher in the endovascular strategy group and the mean cost difference was –£2329 (95% CI –£5489 to £922). At 3 years, mortality was 48% and 56% in the endovascular strategy group and open repair group, respectively (OR 0.73, 95% CI 0.53 to 1.00; p = 0.053), with a stronger benefit for the endovascular strategy in the subgroup of 502 participants in whom repair was started for a proven rupture (OR 0.62, 95% CI 0.43 to 0.89; p = 0.009), whereas aneurysm-related reintervention rates were non-significantly higher in this group. At 3 years, considering all participants, there was a mean difference of 0.174 quality-adjusted life-years (QALYs) (95% CI 0.002 to 0.353 QALYs) and, among the endovascular strategy group, a cost difference of –£2605 (95% CI –£5966 to £702), leading to 88% of estimates in the cost-effectiveness plane being in the quadrant showing the endovascular strategy to be ‘dominant’. Limitations Because of the pragmatic design of this trial, 33 participants in the endovascular strategy group and 26 in the open repair group breached randomisation allocation. Conclusions The endovascular strategy was not associated with a significant reduction in either 30-day mortality or cost but was associated with faster participant recovery. By 3 years, the endovascular strategy showed a survival and QALY gain and was highly likely to be cost-effective. Future research could include improving resuscitation for older persons with circulatory collapse, the impact of local anaesthesia and emergency consent procedures. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 31. See the NIHR Journals Library website for further project information.

Expert commentary

The IMPROVE trial assessed whether or not there was a benefit for EVAR with stents in patients with burst aortic aneurysms – some of our very sickest patients.

This paper discusses the trial in more detail. Like many well run studies, IMPROVE asks more questions than it answers: Are we doing enough emergency abdominal aortic aneurysm surgery, should it only be done by select experts and how can we further improve care and techniques?

We are still on a learning curve with this new technology, and it is likely that this study will not be the last and final word on this treatment.

Harvey Chant, Consultant Vascular Surgeon, Royal Cornwall Hospitals