Summary of the trials
Introduction
Methods
Early and mid-term results for EVAR Trial 1
Mid-term results for EVAR Trial 2
Current interpretation for EVAR Trial 1
Current interpretation for EVAR Trial 2

Introduction
Endovascular aneurysm repair (EVAR) to exclude abdominal aortic aneurysm (AAA) was introduced in the early 1990’s for patients of poor health status considered unfit for major surgery. As the technology has progressed, EVAR has become an alternative choice of treatment for patients considered fit for open repair as it is minimally invasive and generally involves a shorter stay in hospital. The two EndoVascular Aneurysm Repair (EVAR) Trials were instigated to assess the safety and efficacy of endovascular aneurysm repair in the treatment of AAA in terms of mortality, quality of life, durability and cost-effectiveness for patients considered fit for open repair (EVAR Trial 1) or unfit for open repair (EVAR Trial 2).



Methods
Between September 1999 and December 2003, male and female patients aged at least 60 years with an AAA diameter measuring at least 5.5cm on a Computed Tomography (CT) scan were assessed for anatomical suitability for EVAR across 41 eligible UK centres. Suitable patients were offered entry either into EVAR Trial 1 if they were considered fit for conventional open repair or EVAR Trial 2 if they were considered unfit. EVAR 1 randomly allocated patients to EVAR or open repair and EVAR 2 randomly allocated patients to EVAR with medical treatment or medical treatment alone. Target recruitment for EVAR Trials 1 and 2 was 900 and 280 patients respectively. Patients were followed for a minimum of 1 year to 31st December 2004, and were all flagged for mortality at the Office for National Statistics with death certificates reviewed by an independent endpoints committee for cause of death. Patients were also followed in terms of health related quality of life (HRQL), costs and cost effectiveness, graft complications and secondary interventions.



Early and mid-term results for EVAR Trial 1
By the end of planned recruitment on December 31st 2003, 1082 patients had been entered into EVAR Trial 1, 543 allocated EVAR and 539 allocated open repair. Patients (983 men, 99 women) had a mean age of 74 years (SD 6), a mean aneurysm diameter of 6.5 cm (SD 1.0). 94% of patients complied with their allocated treatment and by the end of mid-term follow-up in December 2004, 209 patients had died, 53 from aneurysm-related causes. Early 30-day post-operative mortality was significantly lower in the EVAR group 1.7% versus 4.7%, logistic regression hazard ratio 0.35 [95% CI 0.16-0.77], p=0.009. Four years after randomisation, all-cause mortality was similar (about 28%) comparing the EVAR to the open repair group, hazard ratio 0.90 [95%CI 0.69 -1.18], although there was a persistent reduction in aneurysm-related deaths in the EVAR group (4% vs 7%), hazard ratio 0.55 [95%CI 0.31-0.96], p=0.04. The proportion of patients with post-operative complications within 4 years of randomisation was 41% in the EVAR group, compared to 9% in the open repair group, hazard ratio 4.9 [95% CI 3.5-6.8], p<0.0001 and this has lead to re-interventions in 20% of the EVAR group compared to 6% in the open repair group by 4 years, hazard ratio 2.7 [95% CI 1.8-4.1], p<0.0001. After 12 months there was negligible difference in HRQL between the two groups. The mean hospital costs per patient up to four years were £13257 for the EVAR group versus £9946 for the open repair group, mean difference £3311 (SE 690).



Mid-term results for EVAR Trial 2
By the end of planned recruitment on December 31st 2003, 338 patients had been entered into EVAR Trial 2, 166 allocated EVAR and 172 allocated no intervention. Patients (288 men, 50 women) had a mean age of 76 years (SD 7), a mean aneurysm diameter of 6.7 cm (SD 1.0) and a mean forced lung expiratory volume in 1 second of 1.7L (SD 0.7). 197 patients underwent aneurysm repair and 81% adhered to the allocated treatment. The 30 day operative mortality in the EVAR group was 13/150, 9% [95% CI 5 -15]. By December 2004 there had been 142 deaths, 42 being aneurysm-related; by four years after randomisation 64% of the patients had died. There were no demonstrable differences comparing the EVAR group to the no intervention group in either all-cause mortality, hazard ratio 1.21 [95%CI 0.87 -1.69] or aneurysm-related mortality, hazard ratio 1.01 [95%CI 0.55 -1.84]. The mean hospital costs over four years per patient was £13632 in the EVAR group and £4983 in the no intervention group, mean difference £8649 (SE 1248), with no difference in HRQL scores.



Current interpretation for EVAR Trial 1
EVAR had an ongoing 3% better aneurysm-related survival than open repair but no demonstrable all-cause mortality or HRQL benefit. The continuing need for interventions mandates ongoing surveillance and longer follow-up for detailed cost-effectiveness evaluation.



Current interpretation for EVAR Trial 2
EVAR had a considerable 30 day operative mortality in patients already unfit for open repair of their aneurysm. EVAR did not improve longer-term survival and was associated with a need for continued surveillance and re-interventions, at substantially increased cost. Thus, in these sick patients the emphasis has shifted towards improving patient fitness before considering EVAR, particularly in terms of cardiac, respiratory and renal function. Ongoing follow-up of these patients is an important priority.