OBJECTIVE: Validating NIH-published patient reported outcomes on hand function in Inclusion Body Myositis (IBM) patients against finger flexor, pinch, and grip strength.
BACKGROUND: IBM is the most common acquired myopathy after the age of 45 with no effective treatment. Indolent progression of the disease makes clinical trials challenging due to lack of effective measures. IBM Functional Rating Scale (IBM-FRS) has been used but, specifically, the hand domain scores do not correlate with grip strength, and only change when there is severe loss of grip and finger flexor strength. Several revised items for the IBM-FRS have been published based on patient reported outcomes or RASCH analysis. Our study validates a set of the published patient reported outcomes pertaining hand function in this patient population and compare them to measured finger flexor and grip strength.
DESIGN/METHODS: 121 subjects were recruited at 2019 Annual Patient Conference of the Myositis Association; 83 subjects had diagnosis of IBM, and 38 subjects were healthy individuals. All IBM subjects filled out the IBM-FRS and patient reported outcomes. Finger flexor, pinch, and grip strength of the dominant hand were measured qualitatively and quantitatively. Correlation between IBM-FRS and patient reported outcome scores with finger flexor and grip strength were analyzed.
RESULTS: The patient reported outcome measures have a higher correlation with both finger flexor and grip strength compared with the hand-function IBM-FRS items.
CONCLUSIONS: Our study proposes better ways to assess hand function in IBM patients with new hand function patient reported outcomes and newer quantitative measures.