The Society of Thoracic Surgeons Congenital Heart Surgery Database Mortality Risk Model: Part 1—Statistical Methodology

Abstract

Background This study’s objective was to develop a risk model incorporating procedure type and patient factors to be used for case-mix adjustment in the analysis of hospital-specific operative mortality rates after congenital cardiac operations. Methods Included were patients of all ages undergoing cardiac operations, with or without cardiopulmonary bypass, at centers participating in The Society of Thoracic Surgeons Congenital Heart Surgery Database during January 1, 2010, to December 31, 2013. Excluded were isolated patent ductus arteriosus closures in patients weighing less than or equal to 2.5 kg, centers with more than 10% missing data, and patients with missing data for key variables. Data from the first 3.5 years were used for model development, and data from the last 0.5 year were used for assessing model discrimination and calibration. Potential risk factors were proposed based on expert consensus and selected after empirically comparing a variety of modeling options. Results The study cohort included 52,224 patients from 86 centers with 1,931 deaths (3.7%). Covariates included in the model were primary procedure, age, weight, and 11 additional patient factors reflecting acuity status and comorbidities. The C statistic in the validation sample was 0.858. Plots of observed-vs-expected mortality rates revealed good calibration overall and within subgroups, except for a slight overestimation of risk in the highest decile of predicted risk. Removing patient preoperative factors from the model reduced the C statistic to 0.831 and affected the performance classification for 12 of 86 hospitals. Conclusions The risk model is well suited to adjust for case mix in the analysis and reporting of hospital-specific mortality for congenital heart operations. Inclusion of patient factors added useful discriminatory power and reduced bias in the calculation of hospital-specific mortality metrics.

Development and Validation of the Neonatal Risk Estimate Score for Children Using Extracorporeal Respiratory Support

“…First, it enables hospitals to compare their risk-adjusted performance to peer institutions (5, 6). Second, it can facilitate efficient adjustment between groups, allowing use of observational data to assess whether interventions are efficacious (7, 8).…”

Improving risk adjustment in the PRAiS (Partial Risk Adjustment in Surgery) model for mortality after paediatric cardiac surgery and improving public understanding of its use in monitoring outcomes

“…10,11 In addition, other international risk adjustment systems have started to use comorbidity information as a risk factor, in recognition of its importance. 16,17 Our consultancy visits to English hospitals with the PRAiS software are now complete. Feedback on the software to implement PRAiS and the usefulness of the VLAD charts was very positive; however, a consistent concern, expressed during almost all visits, was the treatment of comorbidity within the PRAiS risk model, highlighting its importance as a risk factor.…”

“…To explore options for modified groupings of comorbidity codes building on the previous categories formed during the development of PRAiS 1, which were Down syndrome, non-Down syndrome congenital comorbidity (all genetic syndromes, clinical constellations of features that constitute a recognised syndrome, and congenital structural defects of organs other than the heart), acquired comorbidity (preoperative comorbidities acquired as a result of heart disease or its treatments, such as renal failure or necrotising enterocolitis) and prematurity (birth at a gestational age of < 37 weeks); and also considering further non-procedural risk factors that have been identified as potentially important within other registry-based studies. 16,17,33,103,104 2. To identify and exclude comorbidity codes represented in the NCHDA data set that may be difficult to define consistently or where existing definitions are not available or applicable.…”

Transcatheter Aortic Valve Replacement in a Young Adult Patient with a Failed Homograft

“…Although a conventional TAVR risk evaluation tool such as Society of Thoracic Surgeons score / EuroSCORE cannot be well applied to this young patient, he was considered high operative risk for surgery due to history of cardiac arrest associated with surgery. Multiple re-operations using cardiopulmonary bypass increase the perioperative risk such as myocardial injury, life threatening arrhythmia, central nervous system injury, wound infection, or mortality, which are rare but ever present [2,10].…”

“…Approximately one third of the patients have a second SAVR within 10 years after their initial SAVR [1]. Implantation of the bioprosthetic valve is an independent predictor of re-operation, which increases the risk of complication and mortality [2].…”