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

Abstract

Objective. Sporadic inclusion body myositis (IBM) is a debilitating idiopathic inflammatory myopathy (IIM) which affects hand function, ambulation, andswallowing. There is no approved pharmacological 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 studies to lay the path for developing a core set of outcome measures in IBM. Methods. In this systematised review, we have extracted all outcome measures reported in IBM clinical studies to determine what measures were being used and to assess the need for optimising 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, IBMfunctional rating scale (IBM-FRS), quantitative muscle testing, manual muscle testing, maximal voluntary isometric 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 clinical 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.

Phenotypic spectrum of inclusion body myositis

“…Nevertheless, dysphagia remains un-derrecognised in IBM, and unless asked specifically about it, patients may not even report symptoms of dysphagia. It has been used as an outcome measure only in three randomised clinical trials in IBM (10,11,29). Physical examination can provide several clues in diagnosing IBM (1,30).…”

Exploring challenges in the management and treatment of inclusion body myositis

“…Six outcome measures have been used as primary and several others as secondary in IBM clinical trials [ 94 ▪ ]. The primary outcome measures included the 6-min walk distance (6MWD), IBMFRS, quantitative muscle testing (QMT) and maximal voluntary isometric contraction testing (MVICT), manual muscle testing (MMT), and thigh muscle volume measured by MRI.…”

“…For instance, the 6-min walk distance test was designed to assess exercise capacity in pulmonary diseases and may be influenced by other nonneuromuscular conditions [ 95 ]. It also has a major flooring effect and cannot be used in IBM patients who have already lost ambulation [ 94 ▪ ]. Muscle strength testing, manually or via dynamometry, lacks standardization with marked intra- and inter-rater variability.…”

Update on the evaluation and management of dysphagia in sporadic inclusion body myositis

“…The Inclusion Body Myositis Functional Rating Scale (IBM-FRS) includes one item related to swallowing, which is rated from 0 (needs tube feeding) to 4 (normal) [11]. It is one of the most widely used outcome measures in IBM trials [12]. Yet, we are unaware of any study that has directly investigated the predictive validity between IBM-FRS, or more specifically the swallowing item, and validated measures of swallowing physiology.…”