INFLAMMATORY MYOPATHIES: P.159Feasibility and validation of modified oculobulbar facial respiratory score (mOBFRS) in sporadic inclusion body myositis

Abstract

Sporadic inclusion body myositis (sIBM) is a neurodegenerative disorder that results in progressive limb muscle weakness with bulbar and respiratory involvement. The leading cause of morbidity and mortality are secondary to bulbar dysfunction. The IBMFRS is a reliable patient reported outcome measure used in sIBM, however, we lack objective scales that can quantitate deterioration in bulbar and respiratory functions. We are conducting a prospective study to test the feasibility of using, and validate the use of the modified oculobulbar facial respiratory score (mOBFRS) in sIBM. The mOBFRS is validated in immune myasthenia gravis. We will evaluate if changes in mOBFRS in sIBM: 1) can be reliably measured on a serial basis; 2) correlate with scores of the existing subjective IBM Functional Rating Scale (IBMFRS) and objective Bulbar Rating Scale (BRS); and 3) can be used as a potential outcome measure in clinical trials. Subjects are tested at baseline, month 6 and month 12. Interim analysis was done using a linear mixed effect model to assess the BRS compared with mOBFRS as fixed effect and a random intercept to account for the with-in subject correlation. Pearson's correlation was calculated between swallow time and subjective swallow ability at each visit. Within the first 12 months 36 subjects have completed visit one, 19 completed month 6, and 4 completed month 12. The mOBFRS score is significantly associated with the BRS along all three visits (p< 0.0001). One score change of mOBFRS leads to an average of 0.39 point change in the BRS. The IBMFRS swallow ability question was compared to the mOBFRS timed swallow test which showed no correlation at any of the three visits. Conducting the mOBFRS in a clinic setting has proved to be feasible. mOBFRS is trending to be a useful measure of bulbar function but the study is ongoing.