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Published on: January 29, 2016
Walking as a Mediator Between Strength and Health-Related Quality of Life in Multiple Sclerosis
Laura B Simaitis1, Elizabeth S Gromisch, Alyssa Demeule
1Department of Physical Therapy, Quinnipiac University, Hamden, Connecticut (L.B.S., A.D., R.M., C.P.); Mandell Center for Multiple Sclerosis, Mount Sinai Rehabilitation Hospital, Trinity Health Of New England, Hartford, Connecticut (E.S.G., H.M.D.); Department of Rehabilitation Medicine, Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, Connecticut (E.S.G., H.M.D.); Department of Medical Sciences, Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, Connecticut (E.S.G.); and Department of Neurology, University of Connecticut School of Medicine, Farmington, Connecticut (E.S.G.).
Abstract:
Background and Purpose: Lower limb (LL) weakness and gait impairment are prevalent among persons with multiple sclerosis (PwMS) and can impede functional independence and impact health-related quality of life (HR-QoL). The purpose of this study was to examine the mediation effect of walking speed and perceived walking ability on the relationship between LL weakness and HR-QoL in ambulatory PwMS.
Methods:
Participants (n = 175) were PwMS in this secondary analysis of a cross-sectional study. Demographics, pain (visual analog scale), fatigue (5-item Modified Fatigue Impact Scale), LL strength (hip extensors [HE] and flexors [HF], knee extensors [KE] and flexors [KF], and ankle plantarflexors [APF] and dorsiflexors [ADF]), Timed 25-Foot Walk, 12-item MS Walking Scale, and HR-QoL (MS Impact Scale-Physical [MSIS-29-Phys] and Psychological [MSIS-29-Psych]) were collected. Bivariate and mediation analyses using Hayes' PROCESS were performed to determine if LL strength had an indirect effect through walking speed or perceived walking ability on physical and psychological HR-QoL while controlling for fatigue and pain.
Results:
There were significant ( P < 0.01) correlations for all strength measures with the MSIS-29-Phys and for HF, KE, KF, and APF with the MSIS-29-Psych. In the mediation analyses, LL strength indirectly influenced PwMS' MSIS-29-Phys through walking speed and perceived walking ability. There was only partial mediation between HE, HF, KF, ADF, and MSIS-29-Phy when walking speed was in the model. LL strength did not influence MSIS-29-Psych.
Discussion And Conclusions:
LL strength impacts physical HR-QoL through walking but does not indirectly affect PwMS' perceived psychological HR-QoL. These findings may prompt physical therapists to create individualized care plans that address LL weakness and walking impairments with the goal of promoting optimal outcomes and improving HR-QoL.
Video Abstract Available:
for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A504 ).
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