Previous analyses have suggested an association between centre volume and in-hospital mortality, post-operative complications, and mortality in those patients who suffer from a complication. We sought to determine the nature of this association using a multicentre cohort.

All the patients, aged 18 years or younger, undergoing heart surgery at centres participating in the European Congenital Heart Surgeons Database (2003–2013) were included. Programmes were grouped as follows: small <150; medium 150–250; large 251–349; very large >350. Multivariable logistic regression was used to identify the differences between groups with the adjusted in-hospital mortality, onset of any and/or major complication, and in-hospital mortality in those patients with any and/or major complication. The outcomes were adjusted for patient specific risk factors and surgical risk factors.

The data set consisted of 119,345 procedures performed in 99 centres. Overall, in-hospital mortality was 4.63%; complications occurred in 23.4% of the patients. In-hospital mortality in patients with complications was 13.82%. Multivariable logistic regression showed that the risk of in-hospital death was higher in low- and medium-volume centres (p<0.001). The rate of the occurrence of any post-operative complication in small, medium, and large programmes was lower compared with very large centres (p<0.001). Low- and medium-volume centres were associated with significantly higher mortality in patients with any complication (p<0.001).

Our analysis showed that the risk of in-hospital mortality was lower in higher-volume centres. Although the risk of complications is higher in high-volume centres, the mortality associated with complications that occurred in these centres was lower.