Interobserver agreement of the anatomic and physiological classification system for adult congenital heart disease.

The Anatomic and Physiological (AP) classification system proposed in the 2018 American College of Cardiology/American Heart Association adult congenital heart disease (ACHD) guidelines assigns 2 dimensions to each patient: anatomic class (AnatC) and physiological stage (PhyS). This approach has not been tested in practice; we assessed interrater reliability and identified sources of disagreement.

METHODS: Consensus definitions for AP categories were developed with input from 4 experts. Research assistants (RAs) assigned AnatC/PhyS for patients in the Boston ACHD Biobank, a prospectively enrolled cohort of ambulatory ACHD patients ≥18 years old seen between 2012 and 2019. Two (of 4) expert reviewers then independently assigned AnatC/PhyS for 41 patients. Interrater reliability was assessed with linearly weighted kappa (κω ) for agreement between (1) experts and (2) an RA and an expert. Experts examined disagreements and identified sources of variability and areas requiring clarification.

RESULTS: Interexpert agreement for AnatC was excellent, with agreement on 38/41 (92.7%) cases and κω 0.88 [0.75, 1.01]. Agreement for PhyS was less robust, with consensus on 24/41 cases (59.5%), κω 0.57 [0.39, 0.75]. Expert-RA agreement was lower for AnatC (κω 0.77 [0.60, 0.95]), whereas PhyS was similar to interexpert agreement (κω 0.53 [0.34, 0.72]). There was ambiguity in the definitions of (1) arrhythmia status, (2) cyanotic CHD, and (3) valve disease.

CONCLUSIONS: Although AnatC can be assessed reliably, that is not true for the PhyS part of the AP classification proposed in the 2018 American College of Cardiology/American Heart Association guidelines. Reliability of PhyS would be strengthened by more precise definitions readily interpretable in clinical practice.