Anatomic and physiologic classification of adults with congenital heart disease to predict adverse outcomes: Use of administrative codes compared to clinical staging.

Background: The 2018 anatomic physiologic (AP) classification American Heart Association/American College of Cardiology (AHA/ACC) Guidelines for Adults with Congenital Heart Disease (ACHD) encompasses both native and post-operative anatomy and physiology to guide care management. As some physiologic conditions and post-operative states lack specific International Classification of Diseases (ICD) 9- Clinical Modification (CM) and 10-CM codes, an ICD code-based classification approximating the ACHD AP classification is needed for population-based studies.

Methods: A total of 232 individuals, aged ≥ 18 years at the time of a health encounter between January 1, 2010 and December 31, 2019 and identified with at least one of 87 ICD codes for a congenital heart defect were validated through medical chart review. Individuals were assigned one of 4 mutually exclusive modified AP classification categories: (1) severe AB, (2) severe CD, (3) non-severe AB, or (4) non-severe CD, based on native anatomy "severe" or "non-severe" and physiology AB ("none" or "mild") or CD ("moderate" or "severe") by two methods: (1) medical record review, and (2) ICD and Current Procedural Terminology (CPT) code-based classification. The composite outcome was defined as a combination of a death, emergency department (ED) visits, or any hospitalizations that occurred at least 6 months after the index date and was assessed by each modified AP classification method.

Results: Of 232 cases (52.2% male, 71.1% White), 28.4% experienced a composite outcome a median of 1.6 years after the index encounter. No difference in prediction of the composite outcome was seen based on modified AP classification between chart review and ICD code-based methodology.

Conclusion: Modified AP classification by chart review and ICD codes are comparable in predicting the composite outcome at least 6 months after classification. Modified AP classification using ICD code-based classification of CHD native anatomy and physiology is an important tool for population-based ACHD surveillance using administrative data.