Children diagnosed with congenital cardiac malformations at the national university departments of pediatric cardiology: positive predictive values of data in the Danish National Patient Registry

INTRODUCTION: The present study was conducted to establish the positive predictive value of congenital cardiac malformation diagnoses registered in the Danish National Patient Registry (NPR), thereby exploring whether the NPR can serve as a valid tool for epidemiologic studies of congenital cardiac malformations. MATERIALS AND METHODS: The study population comprised every individual born from 2000 to 2008 who was registered in the NPR with a congenital cardiac malformation diagnosis and treated at one of the two national departments of pediatric cardiology. Positive predictive values were established comparing NPR information with the clinical record of each individual. RESULTS: A total of 2952 patients with a total of 3536 diagnoses were eligible for validation. Review of their clinical records unveiled no patient without cardiac malformation. In 98% (98%–99%) of the cases, the NPR diagnosis could be found as the discharge diagnosis in the patient’s clinical record, and in 90% (89%–91%) of the cases the NPR diagnosis was considered a true reflection of the patient’s actual malformation. CONCLUSIONS: Our study verifies that the present study population retrieved from the NPR is a valid tool for epidemiological research within the topic of congenital cardiac malformations, given that the research question is not dependent on a fully established sensitivity of the NPR. Precautions should be made regarding cardiac malformations characterized by low prevalence or poor predictive values, and the reported validity should not be extrapolated beyond the study period.