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.