Reliability, validity and responsiveness of physical activity monitors in patients with inflammatory myopathy

Abstract

Objective Idiopathic inflammatory myopathies (IIM) cause proximal muscle weakness, which affect activities of daily living. Wearable physical activity monitors (PAMs) objectively assess continuous activity with potential clinical usefulness in IIM assessment. We examined the psychometric characteristics for PAM outcomes in IIM. Methods Adult IIM patients were prospectively evaluated (baseline, 3 and 6-months) in an observational study. A waist-worn PAM (ActiGraph GT3X-BT) assessed average step counts/min, peak 1-min cadence, and vector magnitude/min. Validated myositis core set measures (CSM) including manual muscle testing (MMT), physician global disease activity (MD global), patient global disease activity (Pt global), extra-muscular disease activity (Ex-muscular global), HAQ-DI, muscle enzymes, and patient-reported physical function were evaluated. Test-retest reliability, construct validity, and responsiveness were determined for PAM measures and CSM using Pearson correlations and other appropriate analyses. Results 50 adult IIM patients enrolled [mean (SD) age, 53.6 (±14.6); 60% female, 94% Caucasian]. PAM measures showed strong test-retest reliability, moderate-to-strong correlations at baseline with MD global (r=-0.37- -0.48), Pt-global (r=-0.43- -0.61), HAQ-DI (r=-0.47- -0.59) and MMT (r = 0.37–0.52), and strong discriminant validity for categorical MMT and HAQ-DI. Longitudinal association with MD global (r=-0.38- -0.44), MMT (r = 0.50–0.57), HAQ-DI (r=-0.45- -0.55), and functional tests (r = 0.30–0.65) were moderate-to-strong. PAM measures were responsive to MMT improvement (≥10%) and moderate-to-major improvement on ACR/EULAR myositis response criteria. Peak 1-min cadence had the largest effect size and Standardized Response Means (SRMs). Conclusion PAM measures showed promising construct validity, reliability, and longitudinal responsiveness; especially peak 1-min cadence. PAMs provide valid outcome measures for future use in IIM clinical trials.

How to manage with telemedicine people with neuromuscular diseases?

“…A recent study on portable activity monitors for idiopathic inflammatory myopathies measuring average step counts/minute; peak 1-min cadence showed high compliance of patients in wearing devices (revealing a high level of patients commitment toward disease) and a very high level of concordance of these measurements with classical in-patient or ambulatory clinical evaluation. It demonstrated validity in register changes in the physical status of neuromuscular patients, with early recognition of worsening [ 28 ].…”

“…It demonstrated validity in register changes in the physical status of neuromuscular patients, with early recognition of worsening [ 28 ].…”

Validation of two simple patient-centered outcome measures for virtual monitoring of patients with idiopathic inflammatory myositis

“…Patient-centered assessments like AL allow more regular and frequent measurements by patients at home or simpler more objective measurements during clinic follow-up may mitigate some of these limitations. Additionally, these may serve as important secondary outcomes to supplement the collection of validated CSMs in clinical trials [14].…”

“…Inclusion criteria were all adults with the diagnosis of PM or DM as per 2017 ACR/EULAR myositis classification criteria who were evaluated at rheumatology clinic between January and March of 2021. Children and those with known symptomatic ILD (dyspnoea VAS ≥ 2), PAH, or significant lower limb arthritis (pain VAS ≥ 2) were excluded due to the nature of the tests being evaluated and the pilot nature of the study [13][14][15]. Patients with other conditions interfering with their physical function, such as severe fibromyalgia, pregnancy, or fractures, were also considered ineligible for enrolment.…”

“…A visible shift of in-person clinical practice to virtual or remote consulting in times of a global pandemic has necessitated a wider use of patient-centered outcomes (PCOMs) and device-based objective measures of disease assessment for remote monitoring of the patients [9][10][11]. A few studies have explored the potential tool for monitoring disease remotely, a realm that may assume larger importance for future optimal disease management [12][13][14].…”