Type A aortic dissection: optimal annual case volume for surgery.

Abstract

The current study proposes a novel volume-outcome (V-O) meta-analytical approach to determine the optimal annual hospital case volume threshold for cardiovascular interventions in need of centralization. This novel method is applied to surgery for acute type A aortic dissection (ATAAD) as an illustrative example. A systematic search was applied to three electronic databases (January 1st 2012 - March 29th 2023). The primary outcome was early mortality in relation to annual hospital case volume. Data were presented by volume quartiles (Qs). Restricted cubic splines were used to demonstrate the V-O relation, and the elbow method was applied to determine the optimal case volume. For clinical interpretation, numbers needed to treat (NNT) were calculated. 140 studies were included, comprising 38276 patients. A significant non-linear V-O effect was observed (p<0.001), with a significant between-quartile difference for early mortality (10.3% [Q4] vs. 16.2% [Q1], p<0.001). The optimal annual case volume was determined at 38 cases/year (95% CI 37-40 cases/year, NNT to save a life in a centre with the optimal volume vs. 10 cases/year = 21). More pronounced between-quartile survival differences were observed for long-term survival (10-year survival [Q4] 69% vs. [Q1] 51%, p<0.001, adjusted HR 0.83, 95% CI 0.75-0.91 per quartile, NNT to save a life in a high-volume [Q4] vs. low-volume centre [Q1) = 6). Using this novel approach, the optimal hospital case volume threshold was statistically determined. Centralization of ATAAD care to high-volume centres may lead to improved outcomes. This method can be applied to various other cardiovascular procedures requiring centralization.