The Relationship Between Aortic Aneurysm Surgery Volume and Peri-Operative Mortality in Australia

Abstract

Operative caseload is thought to be associated with peri-operative mortality following intact aortic aneurysm repair. The aim was to study that association in the Australian setting, which has a unique healthcare provision system and geographical population distribution. The Australasian Vascular Audit database was used to capture volume measurements for both individual surgeon and hospital and to separate it into quintiles (1, lowest, to 5, highest) for endovascular (EVAR), open surgical repair (OSR), and subgroups of repair types between 2010 and 2016. Multivariable logistic regression modelling was used to assess the impact of caseload volumes on in hospital mortality after adjustment for confounders. Volume counts were determined from 14,262 aneurysm repair procedures (4121 OSR, 10,106 EVAR). After exclusions, 2181 OSR (161 complex, 2020 standard) and 7547 EVAR (6198 standard, 1135 complex, 214 thoracic (TEVAR)) elective cases were available for volume analysis. Unadjusted mortality after EVAR was unaffected by either surgeon (Quintile 1, 1.0%; Quintile 5, 0.9%; p=.28) or hospital volume (Quintile 1, 0.8%; Quintile 5, 1.3%; p=.47). However, univariable analysis of the TEVAR subgroup revealed a significant correlation with hospital volume (Quintiles 1-2 vs. Quintiles 3-5; p=.02). Univariable analysis for OSR demonstrated a marginal, non-significant value for surgeon (Quintile 1, 4.0%; Quintile 5, 3.6%; p=.06), but not hospital volume (Quintile 1, 4.7%; Quintile 5, 4.0%; p=.67). After adjustment for confounders hospital volume remained a significant predictor of peri-operative TEVAR mortality (Quintile 1-2 vs. 3-5; OR 5.62, 95% CI 1.27-24.83; p=.02) and surgeon volume a predictor following standard OSR (Quintile 1-2 vs. Quintile 3-5; OR 2.15, 95% CI 1.21-3.83; p=.01). There is an inverse correlation between both surgeon volume of open aortic aneurysm repair, hospital volume of thoracic endovascular aneurysm repair and in hospital mortality. These findings suggest that in Australia TEVAR should be performed by high volume hospitals and OSR by high volume surgeons.