The development and validation of a novel tool for the assessment of bulbar dysfunction in ALS

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PROJECT SUMMARY The ultimate goal of this research is to improve clinical practice standards and expedite the pace of therapeutic trials through the development of a clinical tool for assessing the progression of bulbar dysfunction in amyotrophic lateral sclerosis (ALS). As per patient reports, bulbar dysfunction is the most debilitating consequence of ALS, because it leads to the inability to communicate one’s wishes and to eat normally, and because it increases the risk of serious medical complications such as aspiration pneumonia and choking. The great majority of persons diagnosed with ALS experience the loss of motor function in the muscles responsible for speaking and swallowing. Despite its significant impact on quality of life and widespread in ALS, bulbar dysfunction has not received sufficient research attention to date. Bulbar dysfunction is also typically not assessed in clinical trials, beyond a patient report of symptoms. For these reasons, there is strong agreement among the ALS experts on the need for an objective clinician-administered bulbar dysfunction assessment tool. The overall goal of this project is to design a valid and reliable bulbar motor severity assessment tool - the ALS Index of Bulbar Dysfunction (ALS-IBD). In our preliminary work, we have obtained expert consensus regarding the domains to be included in the tool and then exhaustively sampled the literature identifying a large number of candidate items for assessing bulbar motor dysfunction across the identified domains. Our tool development plan adheres to the current best practices for outcome measure development, which have determined the following specific aims: (1) further refine the candidate items by surveying a cohort of speech- language pathology experts; (2) evaluate inter-rater and test-retest reliability of each item and reduce items based on the pre-set reliability criterion; (3) evaluate construct validity of each reliable item relative to the instrumental measures established in our prior work and the validity of the ALS-IBD as a whole relative to the current symptom-based standards; and finally (4) estimate the ALS-IBD’s responsiveness to change over time and its interpretability in the context of changes that are meaningful to the patients. To achieve these aims, we will recruit 100 people diagnosed with ALS, presenting with a range of bulbar impairment severity. To establish content and face validity of ALS-IBD, we will survey 30 expert speech- language pathologists regarding the content, feasibility, clarity of wording, and response options of the candidate items. To estimate inter-rater and intra-rater reliability, we will administer the ALS-IBD multiple times in a subset of participants. To establish construct validity, the individual item scores will be correlated with the highly sensitive instrumental measures to identify items that are most valid with respect to the constructs that they represent. The instrumental measures will be extracted from the kinematic analyses of oromotor and speech movements; acoustic analyses of syllables and connected speech tasks; aerodynamic measures of voice and cough; and the videofluoroscopic analysis of swallowing. The optimized item set created as a result of the item reliability and validity evaluations will comprise the ALS-IBD. The final version of the tool will be subjected to recalculation of its reliability and the assessment of its construct validity relative to the symptom- based measures (e.g. ALS-Functional Rating Scale – Revised). The ALS-IBD will also be assessed for its responsiveness and interpretability using the change in scores between the baseline session and a second session recorded in six months. This effort will yield a brief, scientifically valid, inexpensive, easy-to-use, clinician-administered assessment tool that can be used to track bulbar disease progression in ALS clinics and as an outcome measure in clinical trials.