The Relationship Between Operative Volume and Peri-operative Mortality After Non-elective Aortic Aneurysm Repair in Australia

Surgeon volume and outcomes following thoracic endovascular aortic repair for blunt thoracic aortic injury

OBJECTIVE

Thoracic endovascular aortic repair (TEVAR) for blunt thoracic aortic injury (BTAI) at high-volume hospitals has previously been associated with lower perioperative mortality, but the impact of annual surgeon volume on outcomes following TEVAR for BTAI remains unknown.

METHODS

We analyzed Vascular Quality Initiative (VQI) data from patients with BTAI that underwent TEVAR between 2013 and 2023. Annual surgeon volumes were computed as the number of TEVARs (for any pathology) performed over a 1-year period preceding each procedure and were further categorized into quintiles. Surgeons in the first volume quintile were categorized as low volume (LV), the highest quintile as high volume (HV), and the middle three quintiles as medium volume (MV). TEVAR procedures performed by surgeons with less than 1-year enrollment in the VQI were excluded. Using multilevel logistic regression models, we evaluated associations between surgeon volume and perioperative outcomes, accounting for annual center volumes and adjusting for potential confounders, including aortic injury grade and severity of coexisting injuries. Multilevel models accounted for the nested clustering of patients and surgeons within the same center. Sensitivity analysis excluding patients with grade IV BTAI was performed.

RESULTS

We studied 1321 patients who underwent TEVAR for BTAI (28% by LV surgeons [0-1 procedures per year], 52% by MV surgeons [2-8 procedures per year], 20% by HV surgeons [≥9 procedures per year]). With higher surgeon volume, TEVAR was delayed more (in <4 hours: LV: 68%, MV: 54%, HV: 46%; P < .001; elective (>24 hours): LV: 5.1%; MV: 8.9%: HV: 14%), heparin administered more (LV: 80%, MV: 81%, HV: 87%; P = .007), perioperative mortality appears lower (LV: 11%, MV: 7.3%, HV: 6.5%; P = .095), and ischemic/hemorrhagic stroke was lower (LV: 6.5%, MV: 3.6%, HV: 1.5%; P = .006). After adjustment, compared with LV surgeons, higher volume surgeons had lower odds of perioperative mortality (MV: 0.49; 95% confidence interval [CI], 0.25-0.97; P = .039; HV: 0.45; 95% CI, 0.16-1.22; P = .12; MV/HV: 0.50; 95% CI, 0.26-0.96; P = .038) and ischemic/hemorrhagic stroke (MV: 0.38; 95% CI, 0.18-0.81; P = .011; HV: 0.16; 95% CI, 0.04-0.61; P = .008). Sensitivity analysis found lower adjusted odds for perioperative mortality (although not significant) and ischemic/hemorrhagic stroke for higher volume surgeons.

CONCLUSIONS

In patients undergoing TEVAR for BTAI, higher surgeon volume is independently associated with lower perioperative mortality and postoperative stroke, regardless of hospital volume. Future studies could elucidate if TEVAR for non-ruptured BTAI might be delayed and allow stabilization, heparinization, and involvement of a higher TEVAR volume surgeon.

Hospital Volume of Elective Abdominal Aortic Aneurysm Repair as a Predictor of Mortality After Ruptured Abdominal Aortic Aneurysm Repair

OBJECTIVE

Registry data suggest that centralising abdominal aortic aneurysm (AAA) surgery decreases the mortality rate after AAA repair. However, the impact of higher elective volumes on ruptured AAA (rAAA) repair associated mortality rates remains uncertain. This study aimed to examine associations between intact AAA (iAAA) repair volume and post-operative rAAA death.

METHODS

Using data from official national registries between 2015 - 2019, all iAAA and rAAA repairs were separately analysed across 10 public hospitals. The following were assessed: 30 day and 12 month mortality rate following open surgical repair (OSR) and endovascular aneurysm repair (EVAR). Associations between the 5 year hospital iAAA repair volumes (organised into tertiles) and rAAA associated mortality rate were analysed, regardless of treatment modality. Receiver operating characteristic (ROC) curves were generated to identify iAAA volume thresholds for decreasing the rAAA mortality rate. Subanalysis by treatment type was conducted. Threshold analysis was repeated with the Markov chain Monte Carlo (MCMC) procedure to confirm the findings.

RESULTS

A total of 1 599 iAAAs (80.2% EVAR, 19.8% OSR) and 196 rAAAs (66.3% EVAR, 33.7% OSR) repairs were analysed. The median and interquartile range of the volume/hospital/year for all iAAA repairs were 39.2 (31.2, 47.4). The top volume iAAA tertile exhibited lower rAAA associated 30 day (odds ratio [OR] 0.374; p = .007) and 12 month (OR 0.264; p < .001) mortality rates. The ROC analysis revealed a threshold of 40 iAAA repairs/hospital/year (EVAR + OSR) for a reduced rAAA mortality rate. Middle volume hospitals for open iAAA repair had reduced 30 day (OR 0.267; p = .033) and 12 month (OR 0.223; p = .020) mortality rates, with a threshold of five OSR procedures/year. The MCMC procedure found similar thresholds. No significant association was found between elective EVAR volumes and ruptured EVAR mortality.

CONCLUSION

Higher iAAA repair volumes correlated with a lower rAAA mortality rate, particularly for OSR. The recommended iAAA repair threshold is 40 procedures/year and five procedures/year for OSR. These findings support high elective volumes for improving the rAAA mortality rate, especially for OSR.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

The Comparison of Endovascular and Open Surgical Treatment for Ruptured Abdominal Aortic Aneurysm in Terms of Safety and Efficacy on the Basis of a Single-Center 30-Year Experience

OBJECTIVE

Ruptured abdominal aortic aneurysm (rAAA) is a critical condition with a high mortality rate. Over the years, endovascular aortic repair (EVAR) has evolved as a viable treatment option in addition to open repair (OR). The primary objective of this study was to compare the safety and efficacy of EVAR and OR for the treatment of rAAA based on a comprehensive analysis of our single-centre 30-year experience.

METHODS

Patients treated for rAAA at the Department of Vascular and Endovascular Surgery, University Hospital Düsseldorf, Germany from 1 January 1993 to 31 December 2022 were included. Relevant information was retrieved from archived medical records. Patient survival and surgery-related complications were analysed.

RESULTS

None of the patient-specific markers, emergency department-associated parameters, and co-morbidities were associated with patient survival. The 30-day and in-hospital mortality was higher in the OR group vs. in the EVAR group (50% vs. 8.7% and 57.1% vs. 13%, respectively). OR was associated with more frequent occurrence of more severe complications when compared to EVAR. Overall patient survival was 56 ± 5% at 12 months post-surgery (52 ± 6% for OR vs. 73 ± 11% for EVAR, respectively) (p < 0.05). Patients ≥70 years of age showed poorer survival in the OR group, with a 12-month survival of 42 ± 7% vs. 70 ± 10% for patients <70 years of age (p < 0.05). In the EVAR group, this age-related survival advantage was not found (12-month survival: ≥70 years: 67 ± 14%, <70 years: 86 ± 13%). Gender-specific survival was similar regardless of the applied method of care.

CONCLUSION

OR was associated with more severe complications in our study. EVAR initially outperformed OR for rAAA regarding patient survival while re-interventions following EVAR negatively affect survival in the long-term. Elderly patients should be treated with EVAR. Gender does not seem to have a significant impact on survival.

Inter-Hospital Transfer of Patients With Ruptured Abdominal Aortic Aneurysm in Switzerland

OBJECTIVE

To analyse the association between inter-hospital transfer and hospital mortality in patients with ruptured abdominal aortic aneurysms (rAAA) in Switzerland.

METHODS

Secondary data analysis of case related hospital discharge data from the Swiss Federal Statistical Office for the years 2009 - 2018. All cases with rAAA as primary or secondary diagnosis were included. Cases with rAAA as a secondary diagnosis without surgical treatment and cases that had been transferred to another hospital without surgical treatment at the referring hospital were excluded. Logistic regression models for hospital mortality were constructed with age, sex, type of admission, van Walraven comorbidity score, type of treatment, insurance class, hospital level, and year of treatment as independent variables.

RESULTS

A total of 1 798 cases with rAAA were treated either surgically (62.5%) or palliatively (37.5%) in Switzerland from 1 January 2009 to 31 December 2018. Of these cases, 72.9% were treated directly (surgically or palliatively) at the hospital of first presentation, whereas 27.1% of all cases with rAAA were transferred between hospitals. The overall crude hospital mortality was 50.3%; being 23.1% in the surgically treated cohort and 95.7% in the palliatively treated cohort. Inter-hospital transfer was associated with better survival compared with patients who were admitted directly (OR 0.52; 95% CI 0.36 - 0.75; p < .001). Treatment in major hospitals was associated with significantly higher mortality rate compared with university hospitals (OR 1.98; 1.41 - 2.79; p < .001). There was no evidence of an association between open repair and hospital mortality (OR 1.06; 0.77 - 1.48; p = .72) compared with endovascular repair.

CONCLUSION

In a healthcare system such as Switzerland's with a highly specialised rescue chain, transfer of haemodynamically stable patients with rAAA is probably safe. In this setting, centralised medical care might outweigh the potential disadvantages of a short delay due to patient transfer. Further studies are needed to address potential confounding factors such as haemodynamic and anatomical features.

Center Volume and Failure to Rescue after Open or Endovascular Repair of Ruptured Abdominal Aortic Aneurysms

BACKGROUND

The correlation between center volume and elective abdominal aortic aneurysm(AAA) repair outcomes is well established; however, these effects for either endovascular(EVAR) or open(OAR) repair of ruptured AAA(rAAA) remains unclear. Notably, the capacity to either avert or manage complications associated with postoperative mortality is an important cause of outcome disparities following elective procedures; however, there is a paucity of data surrounding non-elective presentations. Therefore, the purpose of this analysis was to describe the association between annual center volume, complications, and failure to rescue(FtR) after EVAR and OAR of rAAA.

METHODS

All consecutive endovascular and open rAAA repairs from 2010-2020 in the Vascular Quality Initiative were examined. Annual center volume(procedures/year per center) was grouped into quartiles: EVAR-Q1[<14](3.4%), Q2[14-23](12.8%), Q3[24-37](24.7%), Q4[>38](59.1%); OAR-Q1[<3](5.4%), Q2[4-6](12.8%), Q3[7-10](22.7%), Q4[>10](59.1%). The primary end-point was FtR, defined as in-hospital death after experiencing one of six major complications(cardiac, renal, respiratory, stroke, bleeding, colonic ischemia). Risk-adjusted analyses for inter-group comparisons was completed using multivariable logistic regression.

RESULTS

The unadjusted in-hospital death rate was 16.5% and 28.9% for EVAR and OAR, respectively. Complications occurred in 45% of EVAR(n=1,439/3,188) and 70% of OAR(n=1,366/1,961) patients with corresponding FtR rates of 14%(EVAR) and 26%(OAR). For OAR, Q4-centers had a 43% lower FtR risk(OR 0.57, 95%CI 0.4-0.9;p=.017) compared to Q1 centers. Centers performing >5 OARs/year had a 43% lower risk(OR 0.57, 95%CI 0.4-0.7;p<.001) of FtR and this decreased 4% for each additional 5 procedures performed annually(95%CI .93-.991;p=.013). However, there was no significant relationship between center volume and FtR after EVAR. The risk of FtR was strongly associated with a greater number of complications for both procedures(OR multiplied by 6.5 for EVAR and 1.5 for OAR for each additional complication;p<.0001). Among OAR patients with a single recorded complication, return to the operating room for bleeding had highest risk of in-hospital mortality(OR 4.1, 95%CI 1.1-4.8;p=.034), while no specific type of complication increased FtR risk after EVAR.

CONCLUSIONS

FtR occurs commonly after EVAR and OAR of rAAA within VQI centers. Importantly, increasing center volume was associated with reduced FtR risk after OAR but not EVAR. Complication pattern and frequency predicted FTR after either repair strategy. For stable patients, especially those deemed anatomically ineligible for EVAR, these findings emphasize the need to improve coordination of regional referral networks that centralize rAAAs to high-volume centers. Moreover, hospitals that treat rAAA should invest resources that develop protocols targeting specific complications to mitigate risk of preventable postoperative death.

Higher Surgeon Volume is Associated with Lower Odds of Complication Following TEVAR for Aortic Dissections

OBJECTIVE

This study aimed to understand the impact of surgeon volume on outcomes of thoracic endovascular aortic repair (TEVAR) in patients being treated for aortic dissection.

METHODS

Patients undergoing TEVAR from January 2014 - March 2021 in the Vascular Quality Initiative (VQI) database were analyzed. Patients with aortic dissection who underwent TEVAR were divided into quartiles based on the annual TEVAR volume of their vascular surgeon. The highest quartile, middle two quartiles, and lowest quartile were deemed high volume (HV), moderate volume (MV), and low volume (LV), respectively. Multivariable logistic regressions were performed to compare cohort outcomes in terms any postoperative complication, stroke, spinal cord ischemia, reintervention, and 30-day mortality. A Cox proportional hazard model was used to assess the hazard of overall postoperative mortality.

RESULTS

Amongst 1,217 patients undergoing TEVAR, 321, 621, and 275 were performed by HV, MV, and LV surgeons, respectively. HV performed >19 annual TEVARs, MV surgeons between 5 and 18, and LV surgeons ≤4. Adjusted odds of any postoperative complication revealed that HV and MV surgeons had lower odds of overall postoperative complications [(OR 0.58, (95% CI 0.30 - 0.85), p = 0.011) and (OR 0.60, (95% CI 0.38 - 0.87), p = 0.008)], respectively when compared to LV patients. HV had lower odds of respiratory complications than LV surgeons complications [(OR 0.42, (95% CI 0.17 - 0.93), p = 0.039)]. Adjusted analysis of outcomes including spinal cord ischemia, stroke, myocardial infarction, 30-day mortality, and overall mortality did not reveal statistically significant differences between cohorts.

CONCLUSION

Surgeon volume does not to impact 30-day mortality or long-term mortality after TEVAR for aortic dissection, but the odds of overall postoperative complications were lower for HV and MV surgeons when compared to LV surgeons.

Treatment Outcome Trends for Non-Ruptured Abdominal Aortic Aneurysms: A Nationwide Prospective Cohort Study

OBJECTIVE

The Dutch Surgical Aneurysm Audit (DSAA) initiative was established in 2013 to monitor and improve nationwide outcomes of aortic aneurysm surgery. The objective of this study was to examine whether outcomes of surgery for intact abdominal aortic aneurysms (iAAA) have improved over time.

METHODS

Patients who underwent primary repair of an iAAA by standard endovascular (EVAR) or open surgical repair (OSR) between 2014 and 2019 were selected from the DSAA for inclusion. The primary outcome was peri-operative mortality trend per year, stratified by OSR and EVAR. Secondary outcomes were trends per year in major complications, textbook outcome (TbO), and characteristics of treated patients. The trends per year were evaluated and reported in odds ratios per year.

RESULTS

In this study, 11 624 patients (74.8%) underwent EVAR and 3 908 patients (25.2%) underwent OSR. For EVAR, after adjustment for confounding factors, there was no improvement in peri-operative mortality (aOR [adjusted odds ratio] 1.06, 95% CI 0.94 - 1.20), while major complications decreased (2014: 10.1%, 2019: 7.0%; aOR 0.91, 95% CI 0.88 - 0.95) and the TbO rate increased (2014: 68.1%, 2019: 80.9%; aOR 1.13, 95% CI 1.10 - 1.16). For OSR, the peri-operative mortality decreased (2014: 6.1%, 2019: 4.6%; aOR 0.89, 95% CI 0.82 - 0.98), as well as major complications (2014: 28.6%, 2019: 23.3%; aOR 0.95, 95% CI 0.91 - 0.99). Furthermore, the proportion of TbO increased (2014: 49.1%, 2019: 58.3%; aOR 1.05, 95% CI 1.01 - 1.10). In both the EVAR and OSR group, the proportion of patients with cardiac comorbidity increased.

CONCLUSION

Since the establishment of this nationwide quality improvement initiative (DSAA), all outcomes of iAAA repair following EVAR and OSR have improved, except for peri-operative mortality following EVAR which remained unchanged.

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.

Open versus Endovascular Abdominal Aortic Aneurysm Repair in the Australian Private Sector Over Twenty Years

PURPOSE

Over the past two decades, the proliferation of endovascular surgery has changed the approach to abdominal aortic aneurysm (AAA) repair. In Australia, close to two-thirds of surgical procedures are performed in the private healthcare system. We aimed to describe the trends in AAA repair in the Australian private sector throughout the early 21st century.

MATERIALS AND METHODS

Medicare Benefits Schedule (MBS) statistics were accessed to determine the number of infrarenal open AAA repair (OAR) and endovascular AAA repair (EVAR) procedures performed between January 2000 and December 2019. Population data were extracted from the Australian Bureau of Statistics and used to calculate incidence per 100,000 population. Further analysis was performed according to age, gender, and state.

RESULTS

During the study period, 13,193 (67.0%) EVARs and 6504 (33.0%) OARs were performed in the Australian private sector. OARs fell from 70.5% (n=567) of AAA repairs in 2000 to 15.7% (n=237) in 2019, while EVARs rose from 29.5% (n=151) to 84.3% (n=808). The frequency of EVAR surpassed OAR in 2004. The overall incidence of AAA repair varied minimally over the time period (range: 4.9-6.5 per 100,000 adults per year). AAA repair was more common in males than females (9.7 vs 1.7 per 100,000 population) and more common in older age groups. There was a 4-fold increase in EVAR among males older than 85 years (12.8-57.4 per 100,000 population), the largest rise of any group. The overall EVAR:OAR ratio increased from 0.4 to 5.4. There were considerable state-based discrepancies.

CONCLUSION

The landscape of AAA repair in Australian private sector has drastically changed with a clear preference toward EVAR. EVAR saw increased use across all genders, age groups and states, despite stable rates of AAA surgery. Further research is necessary to compare our findings to national trends in the Australian public sector.