RF18 | PSAT149 Joint Function and Quality of Life in Fibrodysplasia Ossificans Progressiva: Results from an International Burden of Illness Survey of Patients and Family Members

INTRODUCTION: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare genetic disorder of progressive heterotopic ossification, resulting in cumulative loss of joint function and severe disability. We present results from an international, cross-sectional FOP Burden of Illness Survey (NCT04665323) demonstrating the impact of loss of joint function on quality of life (QoL) for patients and their family members. METHODS: Individuals with FOP (survey proxy-completed for patients aged <13 years), their primary caregivers, and other family members (aged ≥18 years) were eligible to participate. Family members who acted as a proxy could also participate themselves, as a family member. The survey was available online from 18Jan21–30Apr21 in 15 countries and 11 languages. The Patient­-Reported Mobility Assessment (PRMA) evaluated range of motion across 12 joints and 3 body regions (total scores range from 0–30; higher scores reflect more severe limitations). PRMA total scores were categorized into four Levels: Level 1, 0–6; Level 2, 7–12; Level 3, 13–18; Level 4, ≥19. To assess the impact of FOP on QoL, patients ≥13 years and their family members completed the EuroQoL health-related QoL questionnaire (EQ-5D-5L; index ranges from <0 [worst health] to 1 [full health]). Descriptive analyses of EQ-5D-5L index scores were performed for each population and by patients’ PRMA Level. Linear regression analyses (adjusted for geographic region) were used to evaluate the relationship between patients’ degree of joint impairment (PRMA total score) and patient or family member EQ-5D-5L index score. RESULTS: 463 survey responses were received from 405 individuals: patient/proxy population, n=219 (patients ≥13 years, n=161; proxies for patients <13 years, n=58); family member population, n=244, of whom 163 identified as primary caregivers. Mean (standard deviation [SD]) EQ-5D-5L index score was 0.24 (0.36) for patients ≥13 years, 0.83 (0.22) for primary caregivers, and 0.85 (0.21) across all family members. For the patient population, mean (SD) EQ-5D-5L index score decreased as PRMA Level increased: Level 1, 0.61 (0.26); Level 2, 0.46 (0.34); Level 3, 0.21 (0.30); Level 4, 0.05 (0.26). There was a significant negative association between PRMA total score and EQ­-5D-5L index score for patients, such that for every 1-unit increase in the PRMA total score of the patient, there was a mean (standard error [SE]) decrease of 0.029 (0.003; p<0.0001) in EQ-5D-5L adjusted for geographic region. For all family members, there was no significant association between EQ-5D-5L and the PRMA total score of the patient (p=0.6737). CONCLUSION: Loss of joint function (as represented by PRMA Level) has a significant, detrimental impact on QoL for patients with FOP. These findings increase understanding of the impact of FOP on patients and their family members, and may help to improve quality of care and access to support for the FOP community. Funding: Sponsored by Ipsen. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Sunday, June 12, 2022 12:48 p.m. - 12:53 p.m.