217P Comparing IBMFRS and sIFA as progression indicators in inclusion body myositis patients from the INSPIRE-IBM trial

Inclusion body myositis (IBM) is a common muscular disorder in individuals over the age of 40 years, characterized by atrophy and progressive muscle weakness. Patient-reported outcomes such as the IBMFRS or the sIFA questionnaire provide valuable insights into disease impact from the patient's perspective on their symptoms, functional limitations, and quality of life. However, it remains a topic of further investigation to determine which of these questionnaires exhibits stronger correlations with disease progression. The INSPIRE-IBM is a natural history study involving 150 IBM patients across 13 different US sites. Evaluations are conducted biannually over two years and patients complete IBMFRS, sIFA, EAT-10, Sydney Swallow Questionnaire, PROMIS, along with manual muscle testing and pulmonary functions tests. This abstract analyzes correlations between IBMFRS and sIFA with the other assessments by regression analysis to identify which is a stronger correlator with disease progression. Preliminary analysis, involving 87 patients who completed three time points, revealed a strong correlation between IBMFRS and sIFA (R2=0.7, p=3.21E-96). Both outcomes show moderate correlation with PFTs (R2 between 0.5-0.7), with no significant difference in strength of correlation. IBMFRS and sIFA exhibit similar correlation with MMTs (R2=0.43, p=0.93). As the study is ongoing, more timepoints will be available per patient closer to the conference date and will be included in the analysis.