Administrative datasets are often used to assess outcomes and quality of pediatric cardiac programs; however their accuracy regarding case ascertainment is unclear. We linked patient data (2004–2010) from the Society of Thoracic Surgeons Congenital Heart Surgery (STS-CHS) Database (clinical registry) and the Pediatric Health Information Systems (PHIS) database (administrative database) from hospitals participating in both to evaluate differential coding/classification of operations between datasets and subsequent impact on outcomes assessment.

Eight individual benchmark operations and the Risk Adjustment in Congenital Heart Surgery, version 1 (RACHS-1) categories were evaluated. The primary outcome was in-hospital mortality.

The cohort included 59,820 patients from 33 centers. There was a greater than 10% difference in the number of cases identified between data sources for half of the benchmark operations. The negative predictive value (NPV) of the administrative (versus clinical) data was high (98.8%–99.9%); the positive predictive value (PPV) was lower (56.7%–88.0%). Overall agreement between data sources in RACHS-1 category assignment was 68.4%. These differences translated into significant differences in outcomes assessment, ranging from an underestimation of mortality associated with truncus arteriosus repair by 25.7% in the administrative versus clinical data (7.01% versus 9.43%; p = 0.001) to an overestimation of mortality associated with ventricular septal defect (VSD) repair by 31.0% (0.78% versus 0.60%; p = 0.1). For the RACHS-1 categories, these ranged from an underestimation of category 5 mortality by 40.5% to an overestimation of category 2 mortality by 12.1%; these differences were not statistically significant.

This study demonstrates differences in case ascertainment between administrative and clinical registry data for children undergoing cardiac operations, which translated into important differences in outcomes assessment.