The Efficacy of a Commercial Physical Activity Monitor in Longitudinal Tracking of Pulmonary Hypertension Patients

Patients with pulmonary arterial hypertension (PAH) have quality of life (QoL) limitations, decreased exercise capacity, and poor prognosis if left untreated. Standard exercise testing is routinely performed for the evaluation of patients with PAH but may be limited in its ability to monitor activity levels in daily living. We evaluated the validity of the commercial Fitbit Charge HR as a tool to assess real time exercise capacity as compared to standard exercise testing in patients with PAH. Ambulatory pediatric and adult PAH patients were enrolled and given a Fitbit with instructions to continuously wear during waking hours. Subjects underwent a 6-minute walk test (6MWT), cardiopulmonary exercise test (CPET) and an SF-36 QoL survey on the day of enrollment and follow-up. Twenty-seven ambulatory subjects with PH were enrolled and 21 had sufficient data for analyses (median age 25, range 13-59, 14 F) were enrolled. Daily steps measured by the Fitbit had a positive correlation with 6MWT distance (r = 0.72, p = 0.03) and an inverse correlation with WHO functional class. On the QoL survey, 77% reported improvement in energy/fatigue (p = 0.055). At follow up there was a strong correlation between Fitbit steps and role limitations due to physical problems (r = 0.88, p = 0.020) and weaker correlations with less related QoL markers. These findings suggest activity monitors may have potential as a simple/novel method of assessing longitudinal exercise capacity and activity levels in PAH patients. Further study in larger cohorts of patients is warranted to determine the best accelerometric correlates with outcomes.