Imel EA et al_Familial hypophosphatemia_Supplementary material.docx

<b>Real-World Clinical and Healthcare Resource Burden Among </b><b>Burosumab-Naïve </b><b>with Familial Hypophosphatemia</b>Objective: To examine the real-world clinical and healthcare resource burden of familial hypophosphatemia (FH). Methods: In a retrospective, observational cohort study using MarketScan® claims data from 2017 to 2021, clinical characteristics and healthcare resource utilization (HCRU) and costs were compared between burosumab-naïve pediatric and adult patients with ≥ 1 FH diagnosis code and matched controls without FH. Patient characteristics were evaluated at baseline, and disease characteristics, HCRU, and costs were evaluated over a 12-month follow-up period. Outcomes were analyzed descriptively. Costs were additionally analyzed using multivariate regression models. Results: Overall, 570 patients with FH and 1710 non-FH matched controls were included. Approximately 10% of study participants were aged &lt; 18 years. Patients with FH had 7.8-fold higher mean baseline comorbidity (Charlson Comorbidity Index). The prevalence of morbidities over the 12-month follow-up period was higher in patients with FH than controls, including renal disease (33% vs 3%), arthralgia (25% vs 10%), osteoarthritis (17% vs 6%), and delayed growth/walking difficulty (16% vs 2%; all <i>P</i> &lt; .001). All-cause HCRU was significantly greater for patients with FH than controls over follow-up, including the proportion of patients with at least one inpatient admission (60% vs 4%), outpatient emergency room visit (52% vs 16%), and outpatient pharmacy prescription (96% vs 71%; all <i>P</i> &lt; .001). The mean annual total healthcare cost per patient was also 22.6-fold higher for patients with FH than controls (adjusted cost difference = $129 643; <i>P</i> &lt; .001). Differences were apparent across all age groups. Conclusions: Compared with non-FH matched controls, burosumab-naïve patients with FH experienced multiple morbidities and had substantially higher HCRU and costs.