1. From the Center for Health Services and Nursing Research (P.M., L.B.) and Interuniversity Institute for Biostatistics and Statistical Bioinformatics (A.B.), Katholieke Universiteit Leuven, and Division of Congenital and Structural Cardiology (P.M., W.B.) and Pediatric Cardiology (M.G.), University Hospitals of Leuven, Leuven, Belgium.