Within-day variability on short and long walking tests in persons with multiple sclerosis.
OBJECTIVE
To compare within-day variability of short (10 m walking test at usual and fastest speed; 10MWT) and long (2 and 6-minute walking test; 2MWT/6MWT) tests in persons with multiple sclerosis.


METHODS
Observational study.


METHODS
MS rehabilitation and research centers in Europe and US within RIMS (European network for best practice and research in MS rehabilitation).


METHODS
Ambulatory persons with MS (Expanded Disability Status Scale 0-6.5).


METHODS
Subjects of different centers performed walking tests at 3 time points during a single day.


METHODS
10MWT, 2MWT and 6MWT at fastest speed and 10MWT at usual speed. Ninety-five percent limits of agreement were computed using a random effects model with individual pwMS as random effect. Following this model, retest scores are with 95% certainty within these limits of baseline scores.


RESULTS
In 102 subjects, within-day variability was constant in absolute units for the 10MWT, 2MWT and 6MWT at fastest speed (+/-0.26, 0.16 and 0.15m/s respectively, corresponding to +/-19.2m and +/-54 m for the 2MWT and 6MWT) independent on the severity of ambulatory dysfunction. This implies a greater relative variability with increasing disability level, often above 20% depending on the applied test. The relative within-day variability of the 10MWT at usual speed was +/-31% independent of ambulatory function.


CONCLUSIONS
Absolute values of within-day variability on walking tests at fastest speed were independent of disability level and greater with short compared to long walking tests. Relative within-day variability remained overall constant when measured at usual speed.
University of Hasselt, REVAL/BIOMED, Belgium. Electronic address: Peter.Feys@uhasselt.be.
Peter
P
Feys
University of Aarhus, Department of Biostatistics, Denmark.
Bo
B
Bibby
Masku Neurological Rehabilitation Center, Finland.
Anders
A
Romberg
Neurorehabilitation Unit, CEMCat, Barcelona, Spain.
Carme
C
Santoyo
National MS Center Melsbroek, Belgium.
Benoit
B
Gebara
Center Neurologique et de Réadaptation Fonctionelle, Fraiture, Belgium.
Benoit Maertens
BM
de Noordhout
Rehabilitation and MS Center Overpelt, Belgium.
Kathy
K
Knuts
MS Mellen Center, Cleveland, United States.
Francois
F
Bethoux
MS hospitals, Ry, Denmark; MS hospitals, Haslev, Denmark.
Anders
A
Skjerbæk
MS hospitals, Ry, Denmark; MS hospitals, Haslev, Denmark.
Ellen
E
Jensen
University of Hasselt, REVAL/BIOMED, Belgium.
Ilse
I
Baert
Berner Klinik Montana, Switzerland.
Claude
C
Vaney
Vrije Universiteit, Amsterdam, The Netherlands.
Vincent
V
de Groot
Aarhus University, Department of Sport Sciences, Denmark.
Ulrik
U
Dalgas
D000328:Adult; D000368:Aged; D004185:Disability Evaluation; D005260:Female; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications*; D019370:Observation; D013997:Time Factors; D016138:Walking / Q000502:physiology*
10 meter walk test; 6 minute walking test; Multiple sclerosis; Outcome measures; Variability; Walking