Associations between upper limb disability on the different levels of the International Classification of Functioning, Disability and Health in people with multiple sclerosis
BACKGROUND: It is unknown how impairments caused by MS have impact on the upper limb capacity, performances and community integration. OBJECTIVES: This study aimed to investigate to which extent impairments explained the variance in 'activity' and 'participation' level measures and to which extent upper limb capacity measures explained perceived performance on the 'activity' level in persons with MS (PwMS) with different dexterity levels. DESIGN: A cross-sectional study. METHODS: One hundred and five PwMS (median EDSS=6.5) were assessed with measures of (a) 'body functions and structures' level: strength, active range of motion of the wrist, tactile sensitivity, tremor, spasticity and pain, (b) 'activity' level: the Nine Hole Peg test (NHPT), Action Research Arm Test (ARAt) and Manual Ability Measure-36 (MAM-36), and (c) 'participation' level: the Community Integration Questionnaire. The sample was split in a low and high dexterity group using the median score of the NHPT. RESULTS: In the total group, muscle strength, tactile sensitivity of the thumb and intention tremor explained 53-64% of the variance in the 'activity' level measures. In the low dexterity subgroup, muscle strength and active range of motion explained 43-71% of the variance in the 'activity' measures. In the high dexterity subgroup, only 35% of the variance in the MAM-36 was explained by muscle strength. Capacity measures (NHPT and ARAT) were moderately to highly associated with perceived performance (MAM-36) in the low dexterity group. LIMITATIONS: Some of the outcome measures showed ceiling effects in PwMS with a high dexterity level. CONCLUSIONS: Upper limb muscle strength is the most important impairment affecting capacity and the perceived performance in daily life. Associations between outcome measures differ between PwMS with different dexterity levels.