Measuring sedentary behaviors in patients with idiopathic pulmonary fibrosis using wrist-worn accelerometers

Introduction: Idiopathic pulmonary fibrosis (IPF) patients suffer increasing functional limitation with disease worsening disease. Increasing time in sedentary behaviour has been associated with poorer quality of life. Determining thresholds for activity in patients with respiratory disease is difficult due to variable cardiorespiratory limitations between individuals. Measuring sedentary behaviour is not confounded by this limitation and may be a better measurement of activity in patients with respiratory disease. Objectives: To measure sedentary time in patients with IPF using wrist-worn accelerometers. Methods: 39 IPF patients wore a GENEActiv actiwatch continually for 7 days. Participants underwent measurement of forced vital capacity, diffusion capacity of carbon monoxide and 6 minute walk distance. Results: Valid data was captured from 35 of 39 participants (89.7%). Mean acceleration intensity recorded in the most active 5 hours of each day (in milli-g) were 43.8milli-g and sedentary time was 551.7 minutes per day. Daily sedentary time correlated moderately with M5 values (Pearson correlation -0.366, p=0.030). Only M5 values predicted sedentary time. No variability in sedentary time was seen by day of the week. There was a trend towards higher one and two-year mortality with increasing sedentary time. Conclusions: Wrist-worn accelerometers reliably collected data and were well tolerated. IPF patients spent long periods of time in sedentary behaviours. Of the standard clinical measures used, 6MWD predicted daily activity but not sedentary time; no clinical measures predicted sedentary time. Increased sedentary time may be associated with poorer outcomes in IPF patients.