Physical activity traits from wrist sensors correlate with clinical status in pediatric pulmonary hypertension

Physical activity (PA) estimated by a wearable sensor may reflect clinical status in pediatric pulmonary hypertension (PH). Prior studies used research-grade hip-anchored sensors or commercial wrist sensors with proprietary scoring algorithms. Wrist sensors offer better acceptability in children, however, their ability to detect associations between PA and clinical characteristics is unknown. Youth 8-18 years with PH [Groups 1-4, functional class (FC) I-II] and healthy controls wore a GENEActiv accelerometer on the non-dominant wrist for 14 days. Raw acceleration data were processed using the open-source GGIR R-package. Participants completed a 6-minute walk distance (6MWD) and quality-of-life questionnaire. Muscle mass and strength were assessed by densitometry and handgrip dynamometry. Most recent cardiac testing was extracted from the medical record. Groups were compared by Fisher's exact test, unpaired t-test, or Wilcoxon rank sum test. Multivariate regression models assessed for associations between PA and clinical metrics. Thirty PH participants (median 13.9 years, 57% female, 57% Group 1, 50% FC I) and 29 controls were included. Total PA was similar. PH participants demonstrated fewer and shorter bouts of moderate-to-vigorous PA ≥10 minutes and more time spent at lower PA intensities. In PH participants, muscle mass was positively associated with PA but 6MWD was negatively associated with PA. PA was not associated with quality-of-life. Within the PH group, worse PA traits were associated with lower FC and worse clinical testing. Wrist sensors reveal deficits in PA traits including reduced moderate-to-vigorous activity bouts and lower intensity gradients in pediatric PH.