Using Dynamometry to Assess Grip Strength over Five Years in Individuals with Multiple Sclerosis
Objectives: In this study we explore the extent that quantitative tests of hand strength are able to detect change over time. We hypothesize that a decline in hand strength will be quantified using a hand-held dynamometer and that individuals with MS progressive disease will show greater decline than those with relapsing disease.
Methods: A longitudinal two year hand function study on 147 individuals with MS was previously conducted. From this original cohort we followed a sub group of fifty-five individuals (40 women; 35 relapsing-remitting MS) with EDSS ranging from 0-8.5 over five years (mean follow-up 4.82 years). Annual hand grip strength was quantitatively measured bilaterally using dynamometry. Symptom duration and EDSS were also collected. Multivariate mixed-effects regression models using a patient-specific random intercepts were used for analysis.
Results: Following adjustment for age, disease subtype, symptom duration and sex, we observed a statistically significant annual decline of -0.91 pounds (95% CI: -1.43 to -0.36; P=0.001) in dominant-hand grip function and of -0.75 pounds (95% CI: -1.30 to -0.18; P=0.01) in weaker hand function. When accounting for MS subtype we observed a marginally stronger rate of decline in weaker and dominant hand function among progressive patients (for changes in dominant hand function: P=0.08; for changes in weaker hand function: P=0.18).
Conclusions: The data presented here show that hand strength is frequently impaired in individuals with MS. Assessing hand strength with a dynamometer is a quantitative way to accurately monitor change over time. It is therefore important to assess hand function when following individuals with MS both in a clinical setting as well as in trials.