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

Idiopathic pulmonary fibrosis (IPF) patients suffer increasing functional limitation with disease worsening disease. Increasing time in sedentary behavior 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 behavior is not confounded by this limitation and may be a better measurement of activity in patients with respiratory disease.

To measure sedentary time in patients with IPF using wrist-worn accelerometers.

Thirty-nine IPF patients wore a GENEActiv actiwatch continually for 7 days. Participants underwent measurement of forced vital capacity, diffusion capacity of carbon monoxide and 6-min walk distance (6MWD).

Valid data was captured from 35 of 39 participants (89.7%). Mean acceleration intensity recorded in the most active 5 h of each day (in milli-g) were 43.8 milli-g and sedentary time was 551.7 min per day. Daily sedentary time correlated moderately with M5 values (Pearson correlation -0.366, P = .030). Only M5 values predicted sedentary time. No variability in sedentary time was seen by day of the week. There was a trend toward higher 1 and 2-year mortality with increasing sedentary time.

Wrist-worn accelerometers reliably collected data and were well tolerated. IPF patients spent long periods of time in sedentary behaviors. 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.