Differential Agreement of Self-Reported Sedentary Behavior and Physical Activity With Accelerometer Measures in Adults With Congenital Heart Disease.

BACKGROUND: Physical activity influences functional capacity and long-term health in adults with congenital heart disease (ACHD), but the accuracy of self-reported activity remains uncertain. METHODS AND RESULTS: In this cross-sectional study, subjects with ACHD underwent physical activity assessment using triaxial accelerometers to quantify sedentary behavior (SB), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Participants were classified into 4 activity profiles based on cohort-specific median values of accelerometer-derived SB time and MVPA. Self-reported activity and SB time were assessed using the International Physical Activity Questionnaire (IPAQ) short form. Agreement between self-reported and accelerometer-derived measures was evaluated, and receiver operating characteristic analysis was performed. Among the 177 participants analyzed, accelerometer-derived SB, LPA, and MVPA, as well as IPAQ-derived SB time, differed significantly across activity profiles (all P<0.001). IPAQ-derived SB time showed good discrimination for identifying the sedentary-inactive profile (area under the curve [AUC]: 0.811). In contrast, IPAQ-derived MVPA showed limited discrimination (AUC: 0.663), largely owing to a pronounced floor effect, with more than half of the participants reporting 0 min of MVPA per week. CONCLUSIONS: IPAQ-reported SB time showed reasonable agreement with objectively measured SB and may be useful for identifying sedentary-inactive individuals with ACHD. However, IPAQ-derived MVPA demonstrated limited agreement with accelerometer-based measures and should be interpreted cautiously.