Physical activity and activity space in patients with pulmonary fibrosis not prescribed supplemental oxygen

Abstract

Background: Patients with pulmonary fibrosis (PF) have impaired quality of life, and research suggests that dyspnea and physical activity are primary drivers. As PF progresses, some patients notice the disease "shrinks their worlds". The objective of this study is to describe movement (both physical activity and activity space) in a cohort of patients with PF of various etiologies who have not been prescribed supplemental oxygen (O2).

Methods: Subjects with PF not on supplemental O2 during the day were enrolled from across the U.S. from August 2013 to October 2015. At enrollment, each subject completed questionnaires and, for seven consecutive days, wore an accelerometer and GPS tracker.

Results: One hundred ninety-four subjects had a confirmed diagnosis of PF and complete, analyzable GPS data. The cohort was predominantly male (56%), Caucasian (95%) and had idiopathic pulmonary fibrosis (30%) or connective tissue disease related-PF (31%). Subjects walked a median 7497 (interquartile range [IQR] 5766-9261) steps per day. Steps per day were correlated with symptoms and several quality of life domains. In a model controlling for age, body mass index, wrist- (vs. waist) worn accelerometer and percent predicted diffusing capacity (DLCO%), fatigue (beta coefficient = -51.5 ± 11.7, p < 0.0001) was an independent predictor of steps per day (model R2=0.34).

Conclusions: Patients with PF, who have not been prescribed O2 for use during the day, have wide variability in their mobility. Day-to-day physical activity is related to several domains that impact quality of life, but GPS-derived activity space is not. Wearable data collection devices may be used to determine whether and how therapeutic interventions impact movement in PF patients.

Trial registration: NCT01961362 . Registered 9 October, 2013.

Conflict of interest statement

Ethics approval and consent to participate

All subjects gave written, informed consent including consent to publish study results. The study was approved by the NJH Institutional Review Board (HS-2790), and the study is registered on Consent for publication

Not Applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1

GPS data from one subject at two time points. Panel a. GPS tracks. Panel b. SDE for the same subject. Panel c. RNB for the Footnote: SDE = standard deviational ellipse; RNB = road network buffer. Data from two timepoints are given to show capabilities of data. Blue = data collected at baseline; green = data collected after supplemental oxygen was started. For both SDE and RNB, larger areas indicated greater activity space

Fig. 2

Flowchart of Enrolled Subjects

Fig. 3

Distribution of Accelerometer-derived measures of physical activity. Footnote: horizontal line = median, box = interquartile range (IQR); whiskers = 1.5IQR; and dots = outliers