Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Apr;29(4-5):606-614.
doi: 10.1177/13524585231152433. Epub 2023 Feb 8.

Personalized monitoring of ambulatory function with a smartphone 2-minute walk test in multiple sclerosis

Ka-Hoo Lam  1 , Ioan Gabriel Bucur  2 , Pim van Oirschot  3 , Frank de Graaf  4 , Eva Strijbis  1 , Bernard Uitdehaag  1 , Tom Heskes  2 , Joep Killestein  1 , Vincent de Groot  5
Affiliations

Personalized monitoring of ambulatory function with a smartphone 2-minute walk test in multiple sclerosis

Ka-Hoo Lam et al. Mult Scler. 2023 Apr.

Abstract

Background: Remote smartphone-based 2-minute walking tests (s2MWTs) allow frequent and potentially sensitive measurements of ambulatory function.

Objective: To investigate the s2MWT on assessment of, and responsiveness to change in ambulatory function in MS.

Methods: One hundred two multiple sclerosis (MS) patients and 24 healthy controls (HCs) performed weekly s2MWTs on self-owned smartphones for 12 and 3 months, respectively. The timed 25-foot walk test (T25FW) and Expanded Disability Status Scale (EDSS) were assessed at 3-month intervals. Anchor-based (using T25FW and EDSS) and distribution-based (curve fitting) methods were used to assess responsiveness of the s2MWT. A local linear trend model was used to fit weekly s2MWT scores of individual patients.

Results: A total of 4811 and 355 s2MWT scores were obtained in patients (n = 94) and HC (n = 22), respectively. s2MWT demonstrated large variability (65.6 m) compared to the average score (129.5 m), and was inadequately responsive to anchor-based change in clinical outcomes. Curve fitting separated the trend from noise in high temporal resolution individual-level data, and statistically reliable changes were detected in 45% of patients.

Conclusions: In group-level analyses, clinically relevant change was insufficiently detected due to large variability with sporadic measurements. Individual-level curve fitting reduced the variability in s2MWT, enabling the detection of statistically reliable change in ambulatory function.

Keywords: Multiple sclerosis; ambulatory function; digital technology; outpatient monitoring; patient-specific modeling; smartphone.

PubMed Disclaimer

Conflict of interest statement

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: P.v.O. and F.d.G. are employees of Sherpa BV and Orikami Digital Health Products, respectively (industry partners). B.M.J.U. received consultancy fees from Biogen Idec, Genzyme, Merck Serono, Novartis, Roche, and Teva. J.K. has accepted speaker and consultancy fees from Merck, Biogen, Teva, Genzyme, Roche, and Novartis. The remaining authors have no conflicts of interest to declare.

Figures

Figure 1.
Figure 1.
Line graphs of clinical outcomes and 2-week averaged s2MWT at each clinical visit from baseline (M0) to 12-month follow-up (M12). T25FW in seconds, EDSS score, and s2MWT in meters. Symbols depict the median value and error bars represent the interquartile range. Abbreviations: T25FW: timed 25-foot walk test; EDSS: Expanded Disability Status Scale; s2MWT: smartphone-based 2-minute walk test.
Figure 2.
Figure 2.
Adherence rates to the scheduled s2MWT throughout the study period. Abbreviations: MS: multiple sclerosis; HC: healthy control.
Figure 3.
Figure 3.
Curve fitting examples showing each of the four most distinct trajectories in smartphone walking function. Each graph encompasses all s2MWT data of a single patient. The upper panels show the s2MWT scores (circles), the LLTM fit (solid line), and its 95% CI (band). Statistically significant change in the estimated s2MWT occurs when there is no overlap in 95% CIs between different time points (shown as dashed arrows). The middle panels show the T25FW scores (dots) with 20% thresholds for clinically relevant change (horizontal bars). Similarly, the lower panels show the EDSS scores with its thresholds for clinically relevant change: 1.5 points if EDSS = 0, 1 point if EDSS between 1.0 and 5.5, or 0.5 points if EDSS ⩾ 6.0. Occurrences of a relevant change in clinical outcomes are denoted by asterisks. Abbreviations: T25FW: timed 25-foot walk test; EDSS: Expanded Disability Status Scale; s2MWT: smartphone-based 2-minute walk test; LLTM: local linear trend model.
See this image and copyright information in PMC

References

    1. Kister I, Chamot E, Salter AR, et al.. Disability in multiple sclerosis. A reference for patients and clinicians. Neurology 2013; 80(11): 1018–1024. - PMC - PubMed
    1. Heesen C, Böhm J, Reich C, et al.. Patient perception of bodily functions in multiple sclerosis: Gait and visual function are the most valuable. Mult Scler 2008; 14(7): 988–991. - PubMed
    1. Sutliff MH.Contribution of impaired mobility to patient burden in multiple sclerosis. Curr Med Res Opin 2010; 26(1): 109–119. - PubMed
    1. Lublin FD, Häring DA, Ganjgahi H, et al.. How patients with multiple sclerosis acquire disability. Brain 2022; 145: 3147–3161. - PMC - PubMed
    1. Scalfari A, Neuhaus A, Daumer M, et al.. Early relapses, onset of progression, and late outcome in multiple sclerosis. JAMA Neurol 2013; 70(2): 214–222. - PubMed

Publication types