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The construct validity of real-world digital mobility outcomes in people with COPD

Lookup NU author(s): Dr Dimitris Megaritis, Dr Silvia Del DinORCiD, Professor Lynn RochesterORCiD

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Abstract

© The authors 2026. Background: Recent advances in wearable technologies make it possible to accurately quantify real-world mobility performance through technically validated digital mobility outcomes (DMOs). The aim of the present study was to evaluate the construct validity (convergent, divergent, and known-groups validity) of 24 DMOs quantifying walking activity (amount and pattern) and gait ( pace, rhythm and bout-to-bout variability) in people with COPD. Methods: Part of the Mobilise-D observational cohort study, people with COPD, recruited from seven European sites, wore an activity monitor for 7 days during daily life. Functional capacity, health status, dyspnoea, lung function, quadriceps torque and experience of difficulty with physical activity were used as constructs for convergent validity testing (Pearson/Spearman correlation coefficients). Diastolic blood pressure was used as an unrelated construct for divergent validity (criterion: |r|<0.2). Known-groups validity was evaluated across Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages (I–IV), GOLD ABE and modified Medical Research Council dyspnoea grades (linear models with p-for-trend). Results 549 participants (37% females), had mean±SD age of 68±8 years, post-bronchodilator forced expiratory volume in 1 s (FEV1) 54±20% predicted and 6-min walk distance 416±119 m. Convergent validity was supported for the majority of DMOs (17 out of 24) with correlation coefficients meeting or exceeding the a priori hypotheses by clinical experts. All DMOs supported divergent validity. 22 out of 24 DMOs distinguished between disease severity groups successfully. Expert consensus supported construct validity of 17 DMOs. Conclusions: Construct validity was supported for all walking activity (amount and pattern) DMOs, and most of the gait ( pace, rhythm, and bout-to-bout variability) DMOs, indicating the clinical utility of these measures.

Publication metadata

Author(s): Megaritis D, Long M, De Las Heras M, Alcaraz-Serrano V, Alvarez P, Becker C, Braun J, Buekers J, Buttery S, Caulfield B, Cereatti A, Chynkiamis N, Del Din S, Delgado-Ortiz L, Demeyer H, Frei A, Gimeno-Santos E, Hopkinson NS, Ionescu A, Jansen C-P, Josa-Cullere A, Kirsten A, Koch S, Lemos J, Philip KEJ, Rochester L, Sharrack B, Singleton D, Vereijken B, Vogiatzis I, Watz H, Lanfranchi V, Troosters T, Garcia-Aymerich J

Publication type: Article

Publication status: Published

Journal: ERJ Open Research

Year: 2026

Volume: 12

Issue: 2

Online publication date: 29/04/2026

Acceptance date: 05/11/2025

Date deposited: 19/05/2026

ISSN (electronic): 2312-0541

Publisher: European Respiratory Society

URL: https://doi.org/10.1183/23120541.00993-2025

DOI: 10.1183/23120541.00993-2025

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