Subjective fitness relates to performance and can be improved by exercise in children and young adults with heart disease.

Abstract

Introduction: The Duke Activity Status Index is used to assess an individual patient's perception of their fitness abilities. It has been validated and shown to predict actual fitness in adults but has been studied less in the paediatric population, specifically those with heart disease. This study aims to assess if the Duke Activity Status Index is associated with measured markers of physical fitness in adolescents and young adults with heart disease.

Methods: This retrospective single-centre cohort study includes patients who completed a minimum of 12 weeks of cardiac rehabilitation between 2016 and 2022. Cardiac rehabilitation outcomes included physical, performance, and psychosocial measures. A comparison between serial testing was performed using a paired t-test. Univariable and multivariable analyses for Duke Activity Status Index were performed. Data are reported as median [interquartile range].

Results: Of the 118 participants (20 years-old [13.9-22.5], 53% male), 33 (28%) completed at least 12 weeks of cardiac rehabilitation. Median peak oxygen consumption was 60.1% predicted [49-72.8%], and Duke Activity Status Index was 32.6 [21.5-48.8]. On Pearson's correlation assessing the Duke Activity Status Index, there were significant associations with % predicted peak oxygen consumption (r = 0.49, p < 0.0001), 6-minute walk distance (r = 0.45, p < 0.0001), Duke Activity Status Index metabolic equivalents (r = 0.45, p < 0.0001), and dominant hand grip (r = 0.48, p < 0.0001). In multivariable analysis, the % predicted peak oxygen consumption (r = 0.40, p = 0.005) and dominant hand grip (r = 0.37, p = 0.005) remained statistically significant.

Conclusions: Duke Activity Status Index is associated with measures of physical fitness in paediatric and young adults with heart disease who complete a cardiac rehabilitation program.