How do people with COPD walk? A European study on digitally measured real-world gait

Abstract

Background: The amount of walking that people with COPD do is reduced. However, data on their manner of walking (i.e. gait) are still lacking. We characterised real-world gait in COPD by assessing levels and distributions of gait parameters, and comparing them across COPD severity and with healthy peers.

Methods: 549 people with COPD from seven European sites and 19 healthy older adults wore single wearable devices (either Axivity AX6 or DynaPort MoveMonitor MM+) continuously for 1 week, from which we identified walking bouts, calculated 15 digital mobility outcomes (DMOs) aggregated at the weekly level, and compared them across COPD severity levels and with healthy peers.

Results: Of the participants with COPD, 37% were female with a mean±sd age of 68±8 years and a post-bronchodilator forced expiratory volume in 1 s of 54±20% predicted. All gait DMOs were normally distributed and exhibited variability between participants (e.g. mean±sd walking speed of 0.83±0.12 m·s^-1, ranging from 0.48 to 1.20 m·s^-1). Walking speed and cadence DMOs were lower with increasing disease severity (e.g. mean±sd walking speed of 0.88±0.11, 0.85±0.12, 0.80±0.12 and 0.78±0.14 m·s^-1 across Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1 to 4, p<0.001; mean±sd cadence of 93±6, 91±6 and 89±7 steps·min^-1 across GOLD A, B and E, p=0.013). Stride length and duration varied across COPD severity levels. Walking speed and cadence bout-to-bout variability only varied across dyspnoea severity levels. In a secondary analysis, we compared DMO data from people with COPD to a convenience sample of 19 healthy older adults (47% women, mean age 71±6 years) and found that walking speed and cadence varied between participants with COPD and healthy adults (e.g. mean±sd walking speed 0.83±0.12 versus 0.90±0.12 m·s^-1, p=0.041).

Conclusion: In people with COPD, gait DMOs are normally distributed and worsen as disease advances. Moreover, walking speed and cadence DMOs are significantly altered when compared to healthy peers. Further research should elucidate which DMOs can be improved with treatments to enhance mobility and reduce adverse events.

Overview of the study. FEV₁: forced expiratory volume in 1 s.

FIGURE 1

Distribution of gait digital mobility outcomes (DMOs) across Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1–4. Shorter walking bouts (WBs) were 10–30 s. Longer WBs were >30 s. p-trends shown across COPD severity stages obtained from linear regression models with COPD severity stages as a continuous variable NA: not applicable. ^#: unadjusted; ^¶: adjusted for age, sex, height, Functional Comorbidity Index and walking duration.

FIGURE 2

Distribution of gait digital mobility outcomes (DMOs) across Global Initiative for Chronic Obstructive Lung Disease (GOLD) ABE groups. Shorter walking bouts (WBs) were 10–30 s. Longer WBs were >30 s. p-trends across COPD severity stages obtained from linear regression models with COPD severity stages as a continuous variable. NA: not applicable. ^#: unadjusted; ^¶: adjusted for age, sex, height, Functional Comorbidity Index and walking duration.

FIGURE 3

Distribution of gait digital mobility outcomes (DMOs) across Modified Medical Research Council (mMRC) Dyspnoea Scale. Shorter walking bouts (WBs) were 10–30 s. Longer WBs were >30 s. p-trends across mMRC grades correspond to linear regression models, with mMRC Dyspnoea Scale grades as a continuous variable. NA: not applicable. ^#: unadjusted; ^¶: adjusted for age, sex, height, Functional Comorbidity Index and walking duration.

FIGURE 4

Differences in gait digital mobility outcomes (DMOs) between 549 people with COPD and 19 healthy older adults. Shorter walking bouts (WBs) were 10–30 s. Longer WBs were >30 s. p-values correspond to linear regression models. ^#: unadjusted; ^¶: adjusted for age, sex, height and walking duration.