{"title":"Psychometric Properties of Free-Living Step-Based Metrics (Daily Steps and Peak Cadence) in Multiple Sclerosis.","authors":"Peixuan Zheng, Robert W Motl","doi":"10.1016/j.apmr.2025.05.005","DOIUrl":null,"url":null,"abstract":"<p><strong>Objective: </strong>We examined the reliability, precision, and clinically detectable change of step-based metrics (daily steps, peak 30-min cadence [Peak-30<sub>CAD</sub>], and peak 1-min cadence [Peak-1<sub>CAD</sub>]) over 6 months in the absence of intervention and evaluated the construct validity through correlations with laboratory-assessed walking and gait performance among persons with multiple sclerosis (MS).</p><p><strong>Design: </strong>Cross-sectional study.</p><p><strong>Setting: </strong>University-based laboratory.</p><p><strong>Participants: </strong>Seventy-eight ambulatory adults (18-64y) with MS.</p><p><strong>Interventions: </strong>Not applicable.</p><p><strong>Main outcome measures: </strong>Free-living physical activity (via ActiGraph GT3X accelerometer), the Timed 25-Foot Walk, 6-minute walk, gait assessment (gait velocity, step length, and time), and disability status (the 12-item MS Walking Scale, Patient-Determined Disease Steps, and Self-Report Expanded Disability Status Scale) were measured before and after 6 months without any intervention.</p><p><strong>Results: </strong>Step-based metrics were stable with no significant changes across time (P>.05) and demonstrated good test-retest reliability (intraclass correlation coefficients: 0.80-0.85) and acceptable precision (SEM%s:14.4%∼24.3%). The minimal detectable changes at 95% CIs (MDC<sub>95</sub>) values for Peak-30<sub>CAD</sub>, Peak-1<sub>CAD</sub>, and daily steps were 25.6 steps/min, 31.0 steps/min, and 2909.2 steps/d, respectively. There were consistent, strong associations between peak cadence with walking tests, gait parameters, and disability status at both time points (|r<sub>s</sub>|=.52-.79), even after controlling for daily steps (|pr<sub>s</sub>|=.25-.58; P<.05).</p><p><strong>Conclusions: </strong>Walking represents an important clinical endpoint in people with MS, yet it is often measured in controlled settings using performance-based tests that might not reflect real-world status. Our findings support step-based metrics via accelerometry as reliable and valid measures of free-living ambulatory performance and may inform the inclusion of these metrics in clinical trials among people with MS.</p>","PeriodicalId":8313,"journal":{"name":"Archives of physical medicine and rehabilitation","volume":" ","pages":""},"PeriodicalIF":3.6000,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Archives of physical medicine and rehabilitation","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1016/j.apmr.2025.05.005","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"REHABILITATION","Score":null,"Total":0}
引用次数: 0
Abstract
Objective: We examined the reliability, precision, and clinically detectable change of step-based metrics (daily steps, peak 30-min cadence [Peak-30CAD], and peak 1-min cadence [Peak-1CAD]) over 6 months in the absence of intervention and evaluated the construct validity through correlations with laboratory-assessed walking and gait performance among persons with multiple sclerosis (MS).
Design: Cross-sectional study.
Setting: University-based laboratory.
Participants: Seventy-eight ambulatory adults (18-64y) with MS.
Interventions: Not applicable.
Main outcome measures: Free-living physical activity (via ActiGraph GT3X accelerometer), the Timed 25-Foot Walk, 6-minute walk, gait assessment (gait velocity, step length, and time), and disability status (the 12-item MS Walking Scale, Patient-Determined Disease Steps, and Self-Report Expanded Disability Status Scale) were measured before and after 6 months without any intervention.
Results: Step-based metrics were stable with no significant changes across time (P>.05) and demonstrated good test-retest reliability (intraclass correlation coefficients: 0.80-0.85) and acceptable precision (SEM%s:14.4%∼24.3%). The minimal detectable changes at 95% CIs (MDC95) values for Peak-30CAD, Peak-1CAD, and daily steps were 25.6 steps/min, 31.0 steps/min, and 2909.2 steps/d, respectively. There were consistent, strong associations between peak cadence with walking tests, gait parameters, and disability status at both time points (|rs|=.52-.79), even after controlling for daily steps (|prs|=.25-.58; P<.05).
Conclusions: Walking represents an important clinical endpoint in people with MS, yet it is often measured in controlled settings using performance-based tests that might not reflect real-world status. Our findings support step-based metrics via accelerometry as reliable and valid measures of free-living ambulatory performance and may inform the inclusion of these metrics in clinical trials among people with MS.
期刊介绍：
The Archives of Physical Medicine and Rehabilitation publishes original, peer-reviewed research and clinical reports on important trends and developments in physical medicine and rehabilitation and related fields. This international journal brings researchers and clinicians authoritative information on the therapeutic utilization of physical, behavioral and pharmaceutical agents in providing comprehensive care for individuals with chronic illness and disabilities.
Archives began publication in 1920, publishes monthly, and is the official journal of the American Congress of Rehabilitation Medicine. Its papers are cited more often than any other rehabilitation journal.
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