Original article
Congenital heart surgery
Higher Programmatic Volume in Neonatal Heart Surgery Is Associated With Lower Early Mortality

Presented at the Fifty-third Annual Meeting of The Society of Thoracic Surgeons, Houston, TX, Jan 21–25, 2017.
https://doi.org/10.1016/j.athoracsur.2017.11.028Get rights and content

Background

The early results of congenital heart surgery in neonates remain a challenge. We sought to determine the nature of the association between annual center volume of neonatal cardiac surgery and operative mortality using a multicenter cohort.

Methods

The dataset consists of 27,556 neonatal procedures performed between 1999 and 2015 in 90 centers participating in the European Congenital Heart Surgeons Association database. Centers with mean annual volume load of six or more that submitted data for at least 3 consecutive years were included. World Bank annual gross national index per capita was utilized as an indicator of temporal national affluence. Multilevel logistic regression was used to create a model including the significant risk factors and to calculate odds ratios for operative mortality. Iterative modeling of the dataset incrementally excluding centers with lower annual caseload was used to identify the relationship between annual volume and mortality.

Results

In the model thus calculated including The Society of Thoracic Surgeons–European Association for Cardio-Thoracic Surgery (STAT) mortality score, operative weight and age, noncardiac genetic anomalies, and annual volume of operations were independent risk factors for operative mortality in the analysis of the entire cohort. In the model containing these variables, annual gross national index and year of surgery were not significantly associated with mortality. In the iterative process, annual volume ceased to be a risk factor when units operating on fewer than 60 neonates annually were excluded.

Conclusions

In neonatal congenital heart surgery, the risk of operative death decreased with the increase of volume load. The cutoff point in this cohort was a mean annual volume of 60 neonatal operations per year.

Section snippets

Material and Methods

The study was carried out according to the ECHSA Congenital Database policy (available at: www.echsacongenitaldb.org, paragraph 2). Because the individual patients were not identified, the ECHSA Congenital Database Committee waived the need for parental consent. The ECHSA database director, according to the policy of the database, accepted the study.

Centers

We identified 27,556 of 29,234 operations in the ECHSA congenital database from January 1, 1999, to December 31, 2015, from 90 centers that met our inclusion criteria. By definition, the minimal data set of these records are complete. These numbers were collected in a total of 722 center-years, making for an average of 8 years per center (SD 4.2; range, 3 to 17). The mean annual neonatal cardiac surgical volume was 1,628 operations per year for the entire cohort (SD 724; range, 116 to 2,414);

Comment

The risk-adjusted odds ratio of annual center volume of neonatal cardiac operations for operative mortality reached its maximum of 1 at 60 operations per center per year. Above 60 operations per center per year, the odds ratio did not change and remained 1, which corresponds to a flat line in the graph visualizing operative mortality and annual volume of neonatal cardiac operations (Fig 2). The power of this finding is substantial owing to the size of the dataset that could only be derived from

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