Physical activity patterns and clusters in 1001 patients with COPD

Abstract

We described physical activity measures and hourly patterns in patients with chronic obstructive pulmonary disease (COPD) after stratification for generic and COPD-specific characteristics and, based on multiple physical activity measures, we identified clusters of patients. In total, 1001 patients with COPD (65% men; age, 67 years; forced expiratory volume in the first second [FEV₁], 49% predicted) were studied cross-sectionally. Demographics, anthropometrics, lung function and clinical data were assessed. Daily physical activity measures and hourly patterns were analysed based on data from a multisensor armband. Principal component analysis (PCA) and cluster analysis were applied to physical activity measures to identify clusters. Age, body mass index (BMI), dyspnoea grade and ADO index (including age, dyspnoea and airflow obstruction) were associated with physical activity measures and hourly patterns. Five clusters were identified based on three PCA components, which accounted for 60% of variance of the data. Importantly, couch potatoes (i.e. the most inactive cluster) were characterised by higher BMI, lower FEV₁, worse dyspnoea and higher ADO index compared to other clusters ( p < 0.05 for all). Daily physical activity measures and hourly patterns are heterogeneous in COPD. Clusters of patients were identified solely based on physical activity data. These findings may be useful to develop interventions aiming to promote physical activity in COPD.

Keywords: Chronic obstructive pulmonary disease; cluster analysis; outcome assessment (healthcare); physical activity; principal component analysis.

Figure 1.

Daily physical activity hourly patterns of the patients with chronic obstructive pulmonary disease after stratification for (a) and (b) – modified Medical Research Council (mMRC) grades, data available for 868 subjects only; (c) and (d) – body mass index (BMI) classification; (e) and (f) – Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades (1 to 4); and (g) and (h) – GOLD groups (a to d). (a), (c), (e) and (g) represent weekdays, while (b), (d), (f) and (h) represent weekend days. Data pooled per hour as mean (95% confidence intervals).

Figure 2.

The five clusters identified. (a) Graph in three dimensions presenting the three principal component analysis (PCA) components; (b) graph in two dimensions presenting the first and second components; (c) graph in two dimensions presenting the first and third components; and (d) graph in two dimensions presenting the second and third components. Details about the relationship between components and clusters can be found in the supplementary material.

Figure 3.

Daily time in activities of very light intensity (a), light intensity (b) and moderate-to-vigorous intensity (c) by clusters of patients with chronic obstructive pulmonary disease. Data are presented as median (interquartile range).

Figure 4.

Daily physical activity hourly pattern of clusters of patients with chronic obstructive pulmonary disease during weekdays (a) and weekend days (b). Data pooled per hour as mean (95% confidence intervals).