Current status of clinical outcome measures in inclusion body myositis: a systematised review

Objective. Sporadic inclusion body my-ositis (IBM) is a debilitating idiopathic inflammatory myopathy (IIM) which affects hand function, ambulation, and swallowing. There is no approved phar-macological therapy for IBM, and there is a lack of suitable outcome measure to assess the effect of an intervention. The IBM scientific interest group under IMACS reviewed the previously used outcome measures in IBM clinical stud-ies to lay the path for developing a core set of outcome measures in IBM.Methods. In this systematised review, we have extracted all outcome meas-ures reported in IBM clinical studies to determine what measures were being used and to assess the need for optimis-ing outcome measures in IBM.Results. We found 13 observational studies, 17 open-label clinical trials, and 15 randomised control trials (RCTs) in IBM. Six-minute walk distance, IBM -functional rating scale (IBM-FRS), quantitative muscle testing, manual muscle testing, maximal voluntary iso-metric contraction testing, and thigh muscle volume measured by MRI were used as primary outcome measures. Twelve different outcome measures of motor function were used in IBM clini-cal trials. IBM-FRS was the most used measure of functionality. Swallowing function was reported as a secondary outcome measure in only 3 RCTs.Conclusion. There are inconsistencies in using outcome measures in clinical studies in IBM. The core set measures developed by the IMACS group for other IIMs are not directly applicable to IBM. As a result, there is an unmet need for an IBM-specific core set of measures to facilitate the evaluation of new potential therapeutics for IBM.