SUN-LB092 The Role of the Modified Performance-Oriented Mobility Assessment Tool in the Evaluation of Gait in Adults with Hypophosphatasia

Introduction: Hypophosphatasia (HPP) is a rare, inherited, systemic, metabolic disorder characterized by a mutation of the ALPL gene, that affects expression of tissue non-specific alkaline phosphatase (TNSALP).(1) Disease manifesta as a myriad of symptoms impairing mobility in patients, including seizures, bone/joint/muscle pain, muscle weakness, pathological fractures, and fatigue. To formally evaluate the impact of these symptoms on mobility in HPP, with or without therapeutic intervention, the modified Performance-Oriented Mobility Assessment (mPOMA-G), a gait assessment tool, has been developed and validated in children with HPP. It has not been formally assessed in adults with HPP; the purpose of this study. Methodology: Retrospective video gait analysis was conducted in a cohort of adult patients with HPP evaluated by physical therapy (PT) at an Academic Medical Center over a two-year period (n=128 [53 individuals], median age:50 years (22-79 years). Scores were analyzed for correlation with relevant medical history and other PT outcome measures. Results: The mPOMA-G score significantly correlated with Functional Gait Assessment, Gait speed and the Six-minute walk tests. ( p values 0.016, 0.035 and <0.001 respectively.) 79% of patients had a mPOMA-G score of ≥10/12, consistent with little gait impairment and did not significantly correlate with Maximum Gait Speed, Five-Times Sit-to-Stand, or Sensory Organization Tests. Significant but weak correlations with ALP levels and treatment with enzyme replacement therapy were demonstrated, but not with and fracture history. Conclusions: While no significant correlations were documented between mPOMA-G performance and disease severity, the significant correlations with other gait measures indicates that the assessed gait deviations are indirectly accounted for with measures of gait speed, endurance, and dynamic balance. The ceiling effect and the low sensitivity of the mPOMA-G suggests a limited utility in accurately assessing gait deficits in adults with HPP. Clinical Relevance: The PT evaluation for adults with HPP at this clinic consists of standardized measurements of gait speed, static and dynamic balance, endurance, and transfers, which can be reliably readministered to assess performance over time. A standardized and qualitative disease-specific measure of gait would be a valuable tool to facilitate optimal management of adult patients with HPP and further research is necessary to develop such an instrument. 1. White MP. Ann NY Acad Sci. 2010; 1192: 190-200.2. Phillips D. et al. Mol Genet Metab. 2016; 119: 14-19. Phillips D. et al. J Pediatr Rehabil Med. 2018; 11(3): 187-192.4. Tomazos I. et al . ESPE Abstracts. 2016; 86: FC2.5.5. Weber TJ. et al. Metabolism. 2016; 65(10): 1522-1530. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.