Ferket et al. (2012) studied in a systematic review article seven English-language guidelines for AAA screening. The consensus was merely about the fact that older men should be subjected to a one-time screening and that AAA> 5.5 cm should be treated. Furthermore, the US Preventive Services Task Force has published a systematic evidence review on the effectiveness of AAA screening (Guirguis-Blake et al. 2014a, b). Review of four randomized trials with a total of 137,214 participants demonstrated that one-time invitation for AAA screening in men aged 65 years and older reduced AAA rupture and aneurysm-related mortality rates (both about 50%) for up to 10–15 years, but had no statistically significant effect on all-cause mortality rates up to 15 years. Screening was associated with more overall and elective surgeries but fewer emergency operations and lower 30-day operative mortality rates at up to 10- to 15-year follow-up. One RCT involving 9342 women showed that screening had no benefit on AAA-related or all-cause mortality rates. The authors pointed out that it would be very optimistic to expect a reduction in the overall mortality rate from a single AAA screening in view of the fact that at the age of 65 years, the AAA prevalence is about 4%. For large aneurysms (>5 cm), the prevalence amounts to as low as only 0.5%, and the rupture rate is low (after 5 years 0.1–0.6%). It should be noted, however, that the late results of the MASS study, considered in isolation, revealed with regard to the overall mortality an advantage for the AAA screening (Thompson et al. 2012). Likewise, the current final report of the German Institute for Quality and Efficiency in Health Care (IQWiG) on ultrasound screening for AAA revealed unlike Guirguis-Blake et al. evidence for an advantage of ultrasound screening with regard to overall mortality in men (IQWiG 2015).

The surveillance intervals of smaller aneurysms depend on their growth rate. For this, a systematic review and meta-analysis of the literature was published (Thompson et al. 2013). According to that, any increase of the aneurysm diameter by 0.5 cm leads to an increase of the aneurysm growth by 0.5 mm/year with a doubling of the rupture risk. The growth rate in smokers is about 0.35 mm/year higher than for former or non-smokers, while conversely diabetics have a slower growth rate by 0.51 mm/year than non-diabetics. The rupture rates are about four times higher in women than in men. In current smokers (men), they are doubled and also patients with hypertension have a higher rupture rate. Based on this analysis, the authors concluded that surveillance intervals of several years are clinically acceptable for men with AAAs in the range of 3.0–4.0 cm. For AAAs from 4.0 to 4.9 cm they recommended an interval of around 1 year, whereas intervals of 6 months would be acceptable for 5.0–5.4-cm AAAs.

A not well-defined risk group that should eventually be included in a screening program, represent women who currently smoke. Based on the Swedish Mammography Cohort (35,550 women) Stackelberg et al. (2014) calculated the AAA incidence per 100,000 women who currently smoke with 136 women, compared with 76 among men who have never smoked. Following smoking cessation, women had a more rapid decline in excess risk. The AAA risk was halved after 11 years among women and after 23 years among men.

Svensjö et al. (2014a) reported the 5-year results of an AAA screening program in the county of Uppsala. In this population-based cohort-study, all men were invited to ultrasound screening of the aorta at age 65, and were re-invited at age 70. From 3268 men, 2736 followed the invitation (83.7%). After 5 years, 23 had completed elective AAA repair, of whom five subsequently had died of non AAA-related causes, and one had undergone rAAA repair and died during surgery. In addition, 239 men were reported dead without a history of AAA repair. Thus, of all men invited at age 65 years, 245 had died resulting in a 5-year mortality of 7.5%. The AAA prevalence increased from 1.5% at 65 to 2.4% at age 70. This data seems to confirm the conclusions of the US Preventive Services Task Force that it is possible to reduce the mortality due to aneurysm rupture with AAA screening, but the impact on overall mortality is rather limited.

In this context, the fact must be mentioned that all four randomized trials on which the screening recommendations of today are based on, expect a AAA prevalence which is no longer up to date. The incidence of AAA is declining in the last decade, at least in some Western European countries; this is also true for the incidence of rAAA, and is explained – among other things – due to a reduction in cigarette consumption (Anjum and Powell 2012; Anjum et al. 2012; Sensi et al. 2013; Svensjö 2013). This makes the screening programs now less effective than on the basis of data such as MASS suspected (Darwood and Brooks 2012). Jacomelli et al. (2016) found in 65-year-old men invited by the NHS AAA Screening Programme the prevalence of AAA (aortic diameter larger than 2.9 cm) was 1.34%. During the period of April 2009 to October 2013, 32,119 men received invitations for AAA screening at the southwest London screening center and 24,891 men were screened (77% attendance) (Benson et al. 2016). Those at highest risk of AAA were white British (1.35%), followed by black and black British (0.65%), and Asian/Asian British (0.23%). Number needed to screen to identify one AAA was calculated as 78, 154, and 431, respectively. In the prospective population-based Oxfordshire-study (Howard et al. 2015) the incidence of acute (acute symptomatic and ruptured) AAA events per 100,000 population per year was 55 in men aged 65–74 years, but increased to 112 at age 75–84 years and to 298 at age 85 years or above. Two-thirds of acute AAA events occurred at age 75 years or above, and more than 25 per cent of events were in women. In this study, the incidence of rAAA in men aged 65–74 years was lower than that found in the MASS trial (55 per 100,000 per year versus 96 per 100,000 per year in the MASS control group). Consistent with this finding, Otterhag et al. (2016) demonstrated a reduction in the overall incidence of rAAA in men during the last decade. They evaluated the Malmö population regarding the incidence of rAAA and elective AAA surgery 4 years before and after start of AAA-screening in 2010. The study demonstrated a reduction in the overall incidence of rAAA in men even before start of AAA screening in the autumn of 2010. Nevertheless, AAA screening in its present form shall be cost-effective (Svensjö et al. 2014b, c). However, Svensjö (2013) indicates 597 as the number of persons to be screened today, to avoid 1 aneurysm-related death, compared with 192 at MASS. This means that one has to screen now three times as many persons as 10 years ago to achieve the same effectiveness of a screening program. Accordingly, the absolute risk reduction for an aneurysm-related death per 10,000 for screening invitees declined from 41.6 to 13.4. The number of years of life gained by screening per 10,000 invitees has also parallely declined (from 131.5 to 46.7 years).

Major RCTs comparing endovascular (EVAR) and open repair (OR) for nonruptured AAA have been published under the titles EVAR 1 (in the UK), DREAM (Netherlands), OVER (USA) and ACE (France).

In EVAR 1, EVAR (n = 614) was compared with OR (n = 602) in patients over 60 years of age with an AAA of at least 5.5 cm in diameter. The mean patient age was 74 years, 90% of the patients were men. Four emergencies respectively were included in both groups (Brown et al. 2012). 30-day mortality was significantly lower in the EVAR group (1.8%) vs. OR (4.3%), which was also true for hospital mortality (2.3% EVAR vs. 6.0% OR). Taking only elective interventions into account, hospital mortality was 2% with EVAR and 5.5% with OR. In the long-term follow-up, the advantage of the lower mortality rate in EVAR could not be sustained, mainly because of fatal endograft ruptures. The overall mortality after >4 years was 8.4 per 100 person-years with EVAR and 7.9 with OR, respectively. The aneurysm-related mortality was calculated to be 0.8 and 0.2 per 100 person-years respectively. Secondary interventions were significantly less after OR (1.7 per 100 person-years compared with 5.1 after EVAR).

In the following DREAM Study (Dutch Randomized Endovascular Aneurysm Management) 178 patients were assigned to OR, and 173 to EVAR (de Bruin et al. 2010). Mean patient age was 70 years, 91.7% of the patients were men, AAA diameter was at least 5 cm. 4.6% of patients died in hospital after OR, and 1.2% after EVAR. The median follow-up was 6.4 years. Six years after randomization, the cumulative overall survival rates were 69.9% for OR and 68.9% for EVAR. The increased perioperative mortality in the open repair group was counterbalanced by a larger number of deaths after discharge in the endovascular-repair group, so that there were no differences in the long-term survival between these two procedures. However, reinterventions were significantly less after OR, 6 years after randomization, the cumulative rates of freedom from secondary interventions were 81.9% for OR and 70.4% for EVAR. De Bruin et al. (2013) also determined renal function of patients of the DREAM study in the long term. Again, there was no difference between OR and EVAR, neither surgical procedure accelerated the loss of renal function. (On a poorer renal function after EVAR compared to OR has been speculated owing to the administration of nephrotoxic contrast agents during intervention). In addition, National Surgical Improvement Program (NSQIP) database demonstrates that moderate renal impairment is not a contraindication for EVAR. Nguyen et al. (2013) identified 13,191 patients who underwent AAA repair: 9877 patients underwent EVAR and 3314 underwent OR. Forty percent of patients had eGFR of less than 60 mL/min. OR in patients with moderate renal dysfunction resulted in significantly higher mortality, cardiovascular events, and combined outcomes. They concluded that contrary to current practice EVAR should be the first choice in patients with moderate renal dysfunction if they have the appropriate anatomy.

In OVER (Open Versus Endovascular Repair) of the Veterans Affairs Cooperative Study Group of the United States, 444 patients with EVAR and 437 patients with OR were included, more than 99% were men, mean age 70 years, mean AAA diameter 5.7 cm (Lederle et al. 2009). Perioperative mortality was significantly higher for open repair at 30 days (0.2% vs 2.3%; P = .006), and at 30 days or during hospitalization (0.5% vs 3.0%; P = .004). This early advantage of EVAR was not offset by increased morbidity or mortality in the first 2 years after repair, mortality after the perioperative period was similar in the two groups (6.1% with EVAR vs 6.6% with OR). The perioperative survival advantage with endovascular repair was sustained for several years, after which there was no significant difference between the two groups. When the study was completed on October 15, 2011, the same percentage of patients had died in both groups (EVAR 32.9%, OR 33.4%) (Lederle et al. 2012). The rates of secondary therapeutic procedures were also similar after EVAR and OR (22.1% vs. 17.8%). In this study late aneurysm rupture remained a concern and EVAR did not yet offer a long-term advantage over open repair, particularly among older patients, for whom such an advantage was originally expected.

In the French ACE-study (Aneurysme de l’aorte abdominale, surgery versus endoprosthesis), 150 patients with an AAA > 50 mm in men or >45 mm in women were assigned to EVAR and 149 patients to OR. Thirty-day mortality was only 0.6% with OR and 1.3% with EVAR (Becquemin et al. 2011). At 3 years, cumulative survival rates were 86.7% with OR and 86.3% with EVAR. In the EVAR group, the crude percentage of vascular reintervention rate was higher (2.7% vs 16%) with a trend toward a higher aneurysm-related mortality (0.7% vs 4%). Incisional complications were significantly more common with OR (25.5% vs. 0.7%), whereas buttock claudication was more frequently seen after EVAR (14% vs. 2%). For patients with low to intermediate risk, these authors further argued for the open approach because it was as safe as EVAR and remained a more durable option.

The existing published randomized trials, together with information from Medicare and SwedVasc databases, were included in a meta-analysis by Stather et al. (2013). This included 25,078 patients undergoing EVAR and 27,142 undergoing open repair for AAA. There was no significant difference in aneurysm-related mortality by 2 years or longer follow-up. A significantly higher proportion of patients undergoing EVAR required reintervention (P = 0.003) and suffered aneurysm rupture (P < 0.001) (Table 4.2). A similar result was shown by the Cochrane Review of Paravastu et al. (2014): in individuals considered fit for conventional surgery, EVAR was associated with lower short-term mortality than OR. However, this benefit from EVAR did not persist at the intermediate- and long-term follow ups.

Bahia et al. (2015) assessed in a systematic review and meta-analysis whether improvements in perioperative practice have translated into better long-term mortality after elective AAA repair over the period 1969–2011. In this study, 5-year survival was 69%. Meta-regression on study midpoint showed no improvement in 5-year survival over the period 1969–2011. After adjusting for average patient age, an improvement in 5-year survival over the period that these data spanned was obtained. The study demonstrated that there has been no measurable improvement in the overall long-term survival of patients undergoing elective infrarenal AAA repair, because increasingly elderly cohorts have been treated over the time period examined. After adjustment for the increasing age of patients undergoing AAA repair, however, long-term survival improved over time.

A meta-analysis on health-related quality-of-life (HR-QoL) outcomes after open versus endovascular AAA repair was performed by Kayssi et al. (2015). SF-36 general health scores were higher for EVAR up to 12 months postoperatively. SF-36 physical functioning scores were higher for EVAR at 6 months but this advantage was lost at 12 months. EVAR was associated with a better EQ-5D score at 12 months, but not at 24 months of follow-up. In conclusion, EVAR was associated with better HR-QoL in some domains up to 12 months postoperatively, but there was insufficient data to demonstrate a HR-QoL advantage beyond 12 months.

The NIS of the U.S. comprises 90,690 patients that underwent repair of unruptured AAA and 11,288 with ruptured AAA in the years 2000–2010 (Dua et al. 2014a). There was a slight decrease from 2000 to 2010 in the incidence of unruptured and rAAA (unruptured AAA, 13.93 to 12.83/ 100,000; rAAA, 2.10 to 1.39/100,000). The overall number of AAAs (unruptured and ruptured) in the U.S. population remained unchanged over this period after correcting for population growth (45,230 estimated total cases in 2000 vs. 44,005 cases in 2010). In 2000, 5.2% of all AAAs were repaired by EVAR (5.9% for unruptured and 0.8% of rAAAs). By 2010, 74.0% of all AAAs were repaired by EVAR (77.8% for unruptured and 38.4% of rAAAs). Although in-hospital mortality rates remained stable for OR in unruptured patients (3.8–4.8%), it declined for EVAR (1.8%–2.1% to 0.9%). Over the same time period, mortality rates for rAAAs repaired by means of OR decreased from 44.5% to 33.4%); those patients undergoing EVAR had a similar decrease for in-hospital mortality rate (40.0%–40.8% to 19.8%). Nearly the same results were seen in the National Surgical Quality Improvement Program (NSQIP) database (Malas et al. 2014). Of the 21,115 patients aged 50 years and older who received elective repair of infrarenal AAA between 2005 and 2011, 5308 (25.1%) received open repair while 15,807 (74.9%) received EVAR. This database showed a significant 3-fold increase in perioperative mortality with open repair compared with EVAR (30-day mortality OR, 3.7; EVAR 1.3%). This difference was independent of risk status and changes over time.

Hicks et al. (2016) used the Nationwide Inpatient Sample database (January 2007–December 2011) to describe the association of patient- and hospital-level factors with in-hospital mortality after elective AAA repair. 131,908 EVARs and 34,535 ORs were performed at 1207 hospitals. Overall in-hospital mortality was 0.7% for EVAR and 3.8% for OR. Mortality after EVAR was significantly higher among hospitals with high general surgery mortality. Mortality after OR was significantly lower among hospitals performing at least 25% of AAA repairs using open techniques. Neither hospital bed size nor teaching status was significantly associated with mortality after either EVAR or OR. Notably, the proportion of institutions performing at least 25% open cases fell from 41% in 2007 to 18% in 2011. This demonstrates the importance of adequate institutional experience with OR techniques, which appears to be critically declining.

Schermerhorn et al. (2015) identified 128,598 Medicare beneficiaries, 67 years of age or older, who had undergone elective repair of abdominal aortic aneurysm from 2001 through 2008; a total of 79,463 patients had undergone endovascular repair, and 49,135 patients had undergone open repair. Perioperative mortality was 1.6% in the endovascular-repair cohort versus 5.2% in the open-repair cohort. Long-term mortality was similar in the two repair cohorts. The rates of reinterventions related to abdominal aortic aneurysm were higher in the endovascular-repair cohort, and these were partially balanced by a higher rate of reinterventions for complications related to laparotomy in the open-repair cohort. Mortality at 2 years after endovascular repair decreased from 16.3% among patients who underwent procedures in 2001 to 14.6% among patients who underwent procedures in 2007, but mortality at 2 years after open repair did not change significantly during that period (16.8% among patients who underwent procedures in 2001 and 15.4% among patients who underwent procedures in 2007).

While the advantage of EVAR compared to OR in high risk patients is uncontroversial, the advantages of EVAR in patients at low risk for open surgical repair (OR) remain unclear. Data of the National Surgical Quality Improvement Program of the United States demonstrate that even among those male patients at low risk for OR on the basis of comorbidities, EVAR is associated with reduced perioperative mortality and major complications. EVAR was associated with lower 30-day mortality (0.5% vs 1.5%; p < .01) compared with OR. The results of this national registry prove the short-term benefit of EVAR in low-risk male patients compared with OR (Siracuse et al. 2014).

Chang et al. (2015) studied the long-term survival and outcomes of EVAR and OR for AAA on a population level. An analysis of the California Office of Statewide Health Planning and Development statewide database from 2001 to 2009 was performed. A total of 23,670 patients with nonruptured AAA were included in this study, for a median follow-up of 3.3 years. EVAR was performed in 51.7% of patients. Thirty-day mortality was 1.5% with EVAR and 4.7% with OR. In this analysis, a survival advantage until 3 years postoperatively for all patients undergoing AAA repair by an endovascular technique was observed (all-cause mortality at 3 years: EVAR 19.8%, OR 19.9%). After 3 years, the mortality rate of EVAR repair patients was higher; however, these mortality differences did not reach statistical significance on adjusted analysis over the entire study (all-cause mortality at 5 years: EVAR 32.1%, OR 29.7%). Reintervention was higher from 6 months through 5 years in EVAR repair patients, which reflects the trends in management of endoleaks and technology available during the study. At 5 years, reintervention rate was 6.6% (EVAR) vs. 1.5% (OR), and AAA rupture occurred in 1.0% (EVAR) vs. 0.2% (OR).

In the Amsterdam Acute Aneurysm Trial (Reimerink et al. 2013) a total of 116 of 520 patients with rAAA of three specialized centers were randomly assigned to either EVAR or OR. Nonrandomized patients were followed in a prospective cohort. Primary endpoint of the study was the composite of death and severe complications at 30 days. The 30-day mortality was 21% in patients assigned to EVAR compared with 25% for OR. The mortality of all surgically treated patients in the nonrandomized cohort was 30%. This trial did not show a significant difference in combined death and severe complications between EVAR and OR (EVAR 42%, OR 47%). Potential limitations of the study were the relatively small numbers of patients included, the high exclusion rate (78%) and the fact that mortality for OR was much lower than expected which could be explained by optimization of logistics, preoperative CT imaging, and centralization of care in centers of expertise.

Meanwhile, the much larger randomized controlled IMPROVE trial of the UK demonstrated no differences in the 30-day mortality between EVAR and OR for rAAA (IMPROVE Trial Investigators et al. 2014a). In this study, 316 patients were randomized to the endovascular strategy and 297 to open repair. In this trial, a strategy of endovascular repair was not associated with significant reduction in either 30-day mortality or cost. Overall 30-day mortality was 35.4% in the endovascular strategy group and 37.4% in the open repair group. However, the endovascular strategy seemed to be more effective in women than in men. For women, 30-day mortality was 26/70 (37%) in the endovascular strategy group and 36/63 (57%) in the open repair group, compared with 86/246 (35%) and 75/234 (32%) for men. Another benefit of EVAR resulted from the fact that 94% per cent of discharges within 30 days were directly to home in the endovascular strategy group compared with only 77% in the OR group.