Debate: Whether abdominal aortic aneurysm surgery should be centralized at higher-volume centers

Editor's Choice - Systematic Review and Meta-Analysis of the Impact of Institutional and Surgeon Procedure Volume on Outcomes After Ruptured Abdominal Aortic Aneurysm Repair

OBJECTIVE

To investigate whether there is a correlation between institutional or surgeon case volume and outcomes in patients with ruptured abdominal aortic aneurysm (rAAA).

DATA SOURCES

The Healthcare Database Advanced Search interface developed by the National Institute of Health and Care Excellence was used to search MEDLINE, Embase, CINAHL, and CENTRAL.

REVIEW METHODS

The systematic review complied with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines with the protocol registered in PROSPERO (CRD42020213121). Prognostic studies were considered comparing outcomes of patients with rAAA undergoing repair in high and low volume institutions or by high and low volume surgeons. Pooled estimates for peri-operative mortality were calculated using the odds ratio (OR) and 95% confidence intervals (CI), applying the Mantel-Haenszel method. Analysis of adjusted outcome estimates was performed with the generic inverse variance method.

RESULTS

Thirteen studies reporting a total of 120 116 patients were included. Patients treated in low volume centres had a statistically significantly higher peri-operative mortality than those treated in high volume centres (OR 1.39; 95% CI 1.22 - 1.59). Subgroup analysis showed a mortality difference in favour of high volume centres for both endovascular aneurysm repair (EVAR; OR 1.61, 95% CI 1.11 - 2.35) and open repair (OR 1.50, 95% CI 1.25 - 1.81). Adjusted analysis showed a benefit of treatment in high volume centres for open repair (OR 1.68, 95% CI 1.21 - 2.33) but not for EVAR (OR 1.42, 95% CI 0.84 - 2.41). Differences in peri-operative mortality between low and high volume surgeons were not statistically significant for either EVAR (OR 1.06, 95% CI 0.59 - 1.89) or open surgical repair (OR 1.18, 95% CI 0.87 - 1.63).

CONCLUSION

A high institutional volume may result in a reduction of peri-operative mortality following surgery for rAAA. This peri-operative survival advantage is more pronounced for open surgery than EVAR. Individual surgeon caseload was not found to have a significant impact on outcomes.

Management of Descending Thoracic Aortic Diseases: Similarities and Differences Among Cardiovascular Guidelines

Cardiovascular societies have developed recommendations regarding the management of thoracic aortic diseases. While improvements in treatment have been observed during the past decade in regard to patient selection, thoracic endovascular aortic repair (TEVAR) and associated techniques, and high-volume centralization, the broad expansion of TEVAR has raised considerations about its indications, appropriateness, limitations, and application. The aim of this systematic review was to assess the similarities and differences among current cardiovascular societies' guidelines for the management of thoracic aortic diseases. The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched from January 2009 to May 2020. The initial search identified 990 articles. After exclusion of duplicate or inappropriate articles, the final analysis included 5 articles from cardiovascular societies published between 2010 and 2020. Selected controversial topics were analyzed, including diagnosis, imaging, spinal cord ischemia prevention, and management of the most important thoracic aortic pathologies. The analysis included data concerning the therapeutic approach in acute and chronic type B aortic dissection, penetrating aortic ulcer, intramural hematoma, thoracic aortic aneurysm, and traumatic aortic injury, as well a discussion of inflammatory aneurysms, aortitis, and genetic syndromes. The review presents consistent and controversial recommendations, as well as "gray zone" issues that need further investigation. There was significant overlap and agreement among the 5 societies regarding the management of thoracic aortic diseases. Especially in dissection and aneurysm management, TEVAR has established its role as the treatment of choice. However, robust evidence is still needed in many aspects of the management of thoracic aortic pathologies.

Impact of Centralisation on Abdominal Aortic Aneurysm Repair Outcomes: Early Experience in Catalonia

OBJECTIVE

Several studies have revealed high volume centres have better outcomes in the treatment of abdominal aortic aneurysms (AAAs), thus supporting centralisation of this procedure into selected centres based on volume. To date however, the real benefit of centralisation of this pathology has not been well demonstrated. The aim of this study was to analyse the impact of centralisation in to high volume centres (defined as those performing more than 30 cases per year) on AAA treatment outcomes carried out in Catalonia (Spain).

METHODS

Data were collected from official national registries (HDMBD) for AAA treated by endovascular aneurysm repair (EVAR) or open repair (OR) over a nine year period. Two time periods were selected for comparison: before centralisation (2009-2014) and after complete centralisation (2015-2017). The primary objective was to determine short term mortality (in hospital and 30 day mortality) and length of stay (LOS) after intact AAA (iAAA) and ruptured AAA (rAAA) repair, before and after centralisation. Uni- and multivariable analyses were performed in order to identify independent outcomes predictors.

RESULTS

A total of 3 501 iAAAs, including 1 124 (32.1%) OR and 2377 (67.9%) EVAR, and 409 rAAAs, including 218 (53.3%) OR and 191 (46.7%) EVAR, were identified. After centralisation, there was a significant decrease in overall mortality in iAAA repair (4.7% vs. 2.0%, p < .001) and rAAA repair (53.1% vs. 41.9%, p = .028). Mortality reduction in iAAAs was significant for OR (8.7% vs. 3.6%, p = .005), but not for EVAR (2.2% vs. 1.5%, p = .25). Overall LOS decreased as well, mainly in iAAAs (9.49 ± 10.84 vs. 7.44 ± 12.23 days, p < .001), and in particular in elective EVAR (7.32 ± 7.73 vs. 6.00 ± 8.97 days, p < .001). Multivariable analysis was identified before the centralisation period as an independent predictor for both mortality (odds ratio 1.484, 95% CI 1.098-2.005, p = .010) and LOS (B coefficient 1.146, 95% CI 0.218-2.073, p = .016).

CONCLUSION

The implementation of a country based centralisation programme for AAA treatment led to a significant reduction in short term mortality, for both iAAA and rAAA, and mainly for elective OR. LOS also significantly decreased, mainly for elective EVAR. These results support the benefit of centralisation of AAA repair procedures.

Use of an Assistant Surgeon Does not Mitigate the Effect of Lead Surgeon Volume on Outcomes Following Open Repair of Intact Abdominal Aortic Aneurysms

OBJECTIVE/BACKGROUND

While higher lead surgeon volume has been associated with lower mortality following open abdominal aortic aneurysm (AAA) repair, little is known about the impact of using an attending surgeon as assistant surgeon. The aim of this study was to determine whether the presence of an assistant surgeon, particularly a high volume assistant, mitigates the relationship between lead surgeon volume and outcomes.

METHODS

All Medicare beneficiaries who underwent intact, open AAA repair between 2003 and 2008 were evaluated and nested regression models were constructed to evaluate the relationship between surgeon and assistant volume and peri-operative mortality, adjusting for comorbid conditions and hospital volume.

RESULTS

In total 28,590 repairs were studied, of which 19,284 (67.5%) were performed by a single surgeon and 9306 (32.5%) included an assistant surgeon. Of cases with an assistant, 12.3% included a high volume assistant surgeon. Lower volume surgeons more frequently used an assistant (lead surgeon Q1 volume: 40%; Q2: 36%; Q3: 34%; Q4: 29%; Q5: 27% [p < .01]). In cases with no assistant, adjusted peri-operative mortality varied monotonically with surgeon volume (Q1: 4.7%; Q2: 4.4%; Q3: 4.1%; Q4: 3.3%; Q5: 3.2%). However, the use of a high or a low volume assistant surgeon, compared with no attending surgeon as assistant, was not associated with lower peri-operative mortality in any lead surgeon volume quintile, even among those operations performed by the lowest volume lead surgeons.

CONCLUSION

Employing an assistant surgeon does not improve outcomes amongst any quintile of volume of the lead surgeon. As surgeons perform fewer open AAA repairs in the modern era, these data imply that even the help of a high volume assistant surgeon may not mitigate the detrimental effect of a lower volume surgeon.

Hospital Teaching Status and Readmission after Open Abdominal Aortic Aneurysm Repair

BACKGROUND

Readmission after abdominal aortic aneurysm (AAA) repair to a different (nonindex) hospital has been shown to be associated with high mortality rates. Factors influencing this association remain unknown. The objective of this study was to determine the impact of hospital teaching status on nonindex hospital readmission and mortality.

METHODS

An observational analysis of the longitudinally linked California Office of Statewide Health Planning and Development database was conducted from 1995 to 2009. Patients who were readmitted within 30 days after open AAA repair were included. The primary outcome measured was mortality on readmission.

RESULTS

Over the 15-year study period, 3,475 readmissions after AAA were analyzed, of which 1,020 (29.4%) were to a nonindex hospital. After adjusting for age, race, gender, insurance, comorbidities, perioperative factors, and reason for readmission, nonindex readmission for patients undergoing their initial operation at a teaching hospital did not impact mortality (odds ratio [OR] 0.78, 95% confidence interval [CI] 0.28-2.17, P = 0.63). Nonindex readmission for patients undergoing their initial operation at a nonteaching hospital, however, significantly increased mortality (OR 1.63, 95% CI 1.04-2.54, P = 0.03).

CONCLUSIONS

Readmission to a different hospital is associated with a higher mortality rate for patients undergoing AAA repair at nonteaching hospitals. This effect is not seen in patients having their initial operation performed at teaching hospitals, possibly due to infrastructure at these hospitals allowing for decreased impact from fragmentation of care. In cases where triage to an index hospital for readmission is not possible, communication at a high level between the index hospital and readmission hospital is paramount.

National trends in open surgical, endovascular, and branched-fenestrated endovascular aortic aneurysm repair in Medicare patients

BACKGROUND

Open repair effectively prevents rupture for patients with abdominal aortic aneurysm (AAA) and is commonly studied as a metric reflecting hospital and surgeon expertise in cardiovascular care. However, given recent advances in endovascular aneurysm repair (EVAR), such as branched-fenestrated EVAR, it is unknown how commonly open surgical repair is still used in everyday practice.

METHODS

We analyzed trends in open AAA repair, EVAR, and branched-fenestrated EVAR for AAA in Medicare beneficiaries from 2003 to 2013. We used Medicare Part B claims to ascertain counts of these repair types annually during the study period. We assessed regional and national trends in characteristics of the patients and procedure volume.

RESULTS

Between 2003 and 2013, the total number of AAA repairs performed in fee-for-service Medicare patients declined by 26% from 31,582 to 23,421 (P < .001), after a peak number of 32,540 was performed in 2005 (28% decline since 2005). The number of open AAA repairs steadily declined by a total of 76%, from 20,533 in 2003 to 4916 in 2013 (P < .001). Whereas the number of EVARs increased from 11,049 in 2003 to 19,247 in 2011 (P < .001), it has since declined a total of 15% to only 16,362 repairs in 2013 (P < .001). After its introduction in 2011, the number of branched-fenestrated EVAR cases continuously rose from 335 procedures in 2011 to 2143 procedures in 2013 (P < .001). By 2013, virtually all hospital referral regions in the United States had rates of open AAA repair that would have been in the lowest quintile of volume in 2003.

CONCLUSIONS

The number of open AAA repairs fell by nearly 80% during the last decade, whereas traditional EVAR declined slightly and branched-fenestrated EVAR rapidly disseminated into national practice. These results suggest that open AAA repair is now performed too infrequently to be used as a metric in the assessment of hospital and surgeon quality in cardiovascular care. Furthermore, surgical training paradigms will need to reflect the changing dynamics necessary to ensure that surgeons and interventionists can safely perform these high-risk surgical procedures.

Reporting individual surgeon outcomes does not lead to risk aversion in abdominal aortic aneurysm surgery

INTRODUCTION Reporting surgeons' outcomes has recently been introduced in the UK. This has the potential to result in surgeons becoming risk averse. The aim of this study was to investigate whether reporting outcomes for abdominal aortic aneurysm (AAA) surgery impacts on the number and risk profile (level of fitness) of patients offered elective treatment. METHODS Publically available National Vascular Registry data were used to compare the number of AAAs treated in those centres across the UK that reported outcomes for the periods 2008-2012, 2009-2013 and 2010-2014. Furthermore, the number and characteristics of patients referred for consideration of elective AAA repair at a single tertiary unit were analysed yearly between 2010 and 2014. Clinic, casualty and theatre event codes were searched to obtain all AAAs treated. The results of cardiopulmonary exercise testing (CPET) were assessed. RESULTS For the 85 centres that reported outcomes in all three five-year periods, the median number of AAAs treated per unit increased between the periods 2008-2012 and 2010-2014 from 192 to 214 per year (p=0.006). In the single centre cohort study, the proportion of patients offered elective AAA repair increased from 74% in 2009-2010 to 81% in 2013-2014, with a maximum of 84% in 2012-2013. The age, aneurysm size and CPET results (anaerobic threshold levels) for those eventually offered elective treatment did not differ significantly between 2010 and 2014. CONCLUSIONS The results do not support the assumption that reporting individual surgeon outcomes is associated with a risk averse strategy regarding patient selection in aneurysm surgery at present.

Minimum volume standards in German hospitals: do they get along with procedure centralization? A retrospective longitudinal data analysis

BACKGROUND

Compliance with minimum volume standards for specific procedures serves as a criterion for high-quality patient care. International experiences report a centralization of the respective procedures. In Germany, minimum volume standards for hospitals were introduced in 2004 for 5 procedures (complex esophageal and pancreatic interventions; liver, kidney and stem cell transplantations), in 2006 total knee replacement was added. This study explores whether any centralization is discernible for these procedures in Germany.

METHODS

A retrospective longitudinal analysis of secondary data serves to determine a possible centralization of procedures from the system perspective. Centralization means that over time, fewer hospitals perform the respective procedure, the case volume in high-volume hospitals increases together with their percentage of the annual total case volume, and the case volume in low-volume hospitals decreases together with their percentage of the annual total case volume. Using data from the mandatory hospital quality reports for the years 2006, 2008 and 2010 we performed Kruskal Wallis and chi-square tests to evaluate potential centralization effects.

RESULTS

No centralization was found for any of the six types of interventions over the period from 2006 to 2010. The annual case volume and the number of hospitals performing interventions rose at differing rates over the 5-year period depending on the type of intervention. Seven percent of esophagectomies and 14% of pancreatectomies are still performed in hospitals with less than 10 interventions per year.

CONCLUSIONS

For the purpose of further centralization of interventions it will be necessary to first analyze and then appropriately address the reasons for non-compliance from the hospital and patient perspective.

Determination of patient preference for location of elective abdominal aortic aneurysm surgery

OBJECTIVE

Aneurysm repair is centralized in higher volume centers resulting in reduced mortality, with longer travel distances. The purpose of this study is to explore patients' preference between local care versus longer distances and lower mortality rates.

METHODS

Patients with abdominal aortic aneurysm (AAA) measuring 4 to 5 cm and living at least a 1-hour drive from our hospital were asked to assume it had grown to 5.5 cm, and repair was recommended with a mortality risk of 2%. The level of additional risk they would accept to undergo surgery locally was determined.

RESULTS

A total of 67 patients were surveyed. If mortality risk was equivalent at the local and regional hospitals, 44% preferred care at our tertiary center, while 56% preferred surgery locally. If perioperative mortality was increased at the local hospital, 9% preferred local surgery.

CONCLUSIONS

The vast majority of patients with AAA will accept longer travel distances for care as long as it results in a reduction in perioperative mortality.

Towards national surgical surveillance in the UK--a pilot study

OBJECTIVE

The Bristol heart inquiry in the United Kingdom (UK) highlighted the lack of standards for evaluating surgical performance and quality. In 2009, the World Health Organisation (WHO) proposed six standardised metrics for surgical surveillance. This is the first study to collect and analyse such metrics from a cohort of National Health Service (NHS) Trusts in England, helping to determine their feasibility and utility in measuring surgical performance, its impact on public health and mortality, and for tracking surgical trends over time.

METHODS

Freedom of Information Act 2000 (FOI) requests for WHO standardised surgical metrics were made to 36 NHS Trusts in England during July to November 2010. Additional data on Hospital Standardised Mortality Ratio (HSMR), Patient Safety Score and Abdominal Aortic Aneurysm (AAA) volume and mortality was obtained from Dr Foster Health and The Guardian Newspaper. Analysis was performed using mixed-effect logistic regression.

RESULTS

30/36 trusts responded (83%). During 2005-9, 5.4 million operations were performed with a 24.2% increase in annual number of operations. This rising volume within hospitals was associated with lower mortality ratios. A 10% increase in operative volume was associated with a lower day of surgery death rate (DDR OR = 0.94, p = 0.056) and post-operative inpatient 30-day mortality (PDR30 OR = 0.93, p = 0.001). For every 10,000 more operations that an NHS Trust does, a 4% drop in PDR30 mortality was achieved. A 10% increase in the volume of elective AAAs was associated with lower elective AAA (OR = 0.96, p = 0.032) and emergency AAA (OR = 0.95, p = 0.009) PDR30 mortality. Lower DDR mortality was noted for emergency AAA mortality (OR = 0.95, p = 0.025) but not elective AAAs (OR = 0.97, p = 0.116).

CONCLUSION

Standarised surgical metrics can provide policy makers and commissioners with valuable summary data on surgical performance allowing for statistical process control of a complex intervention. This study has shown their collection is feasible albeit using FOI and the first to show a statistically significant volume-outcome relationship for surgery as a whole within hospitals. It adds weight to the argument that patients are safer in larger hospitals or those that become larger by growing their patient base. Together with other measures, such metrics can help build a picture of surgical surveillance in the UK and potentially lead us to safer surgery.