O-018 - EUROPEAN AND NORTH AMERICAN ENDORSED OPEN AAA VOLUME THRESHOLDS FAIL TO SUFFICIENTLY DISCRIMINATE PERIOPERATIVE MORTALITY

TOPIC:
Abdominal Aortic Aneurysms
AUTHORS:
Scali S. (University of Florida ~ Gainesville ~ United States of America) , Wanhainen A. (Department of Surgical Sciences, Vascular Surgery, Uppsala University ~ Uppsala ~ Sweden) , Debus S. (Department of Vascular Medicine, Working Group GermanVasc, University Medical Center Hamburg-Eppendorf ~ Hamburg ~ Germany) , Mani K. (Department of Surgical Sciences, Vascular Surgery, Uppsala University ~ Uppsala ~ Sweden) , Behrendt C. (Department of Vascular Medicine, Working Group GermanVasc, University Medical Center Hamburg-Eppendorf ~ Hamburg ~ Germany) , D'Oria M. (Division of Vascular and Endovascular Surgery, Cardiovascular Department, University Hospital of Trieste ASUGI ~ Trieste ~ Italy) , Huber T. (University of Florida ~ Gainesville ~ United States of America) , Powell R. (Section of Vascular Surgery and Endovascular Therapy, Dartmouth-Hitchcock Medical Center ~ Lebanon ~ United States of America) , Stone D. (Section of Vascular Surgery and Endovascular Therapy, Dartmouth-Hitchcock Medical Center ~ Lebanon ~ United States of America)
Introduction:
Current European Society for Vascular Surgery (ESVS) guidelines endorse a minimum open AAA repair (OAAA) center volume of 20 procedures per year as a proxy for high-quality care. By contrast, the Society for Vascular Surgery (SVS) and LeapFrog Group espouse only 10 OAAA repairs per year. Accordingly, debate persists with real-world implications regarding surgeon credentialing and healthcare resource allocation. The purpose of this analysis was to determine which endorsed threshold better discriminates OAAA repair mortality.
Methods:
All elective OAAA repairs from 2010-2020 in the Vascular Quality Initiative (VQI) were identified and center level outcome comparisons were made using ESVS (≥20) vs. SVS/Leapfrog (≥10) volume thresholds. The primary outcome was in-hospital mortality. Logistic regression was used for risk-adjusted comparisons.
Results:
A total of 8,761 OAAA repair procedures were performed at 193 centers across North America. Median annual center volume was 6.6 [IQR 3.3, 9.9] OAAAs per year. Overall, in-hospital mortality was 3.5% (n = 303). The proportion of centers meeting ESVS and SVS/Leapfrog volume thresholds was only 12% (n = 22) vs. 25% (n = 48), respectively. There was an absolute difference in observed mortality of 0.3% among centers performing ≥ 20 vs. ≥ 10 OAAA repairs per year (2.6% vs. 2.9%). There was a significant linear association between center volume and mortality; however, the effect between ESVS (≥ 20) vs. SVS/LeapFrog (≥10) was small (risk decreased 0.2% per procedure; OR multiplies by 0.98 for each unit increase in volume, 95%CI .97-.99; p = 0.0003) (Figure). Moreover, there was no difference in the risk-adjusted protective effect of treatment at centers with either ≥10 or ≥20 cases per year (≥10 vs. <10, OR = 0.66 (.49 - .88), p = 0.005; ≥ 20 vs. < 20, OR = 0.63 (.45 - .87), p = 0.005; p-value for comparison of ORs = 0.78). Lastly, there was no significant difference in the projected percentage of deaths avoided based upon center volume thresholds (≥ 20, 3.3% vs. ≥10, 3.4%).
Conclusion:
It appears that the SVS/LeapFrog recommended OAAA repair volume threshold of ≥10 discriminates perioperative mortality as effectively as ESVS ≥20 procedures per year. Moreover, it should be emphasized that a majority of North American hospitals fail to meet either the ESVS or SVS/Leapfrog operative benchmarks, calling into question the utility of competing recommended center volume guidelines. Based on these findings, a volume alone approach may fail to optimize AAA outcomes. Rather, alternative processes to align care delivery with documented high-performing centers may better serve to enhance international AAA repair.
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