Familial Hypophosphatemia Increases Clinical Burden, Health Care Costs

Patients with familial hypophosphatemia have substantially more comorbidities, health care resource utilization (HCRU), and medical costs than those without hypophosphatemia, according to the results of a study published in the Journal of the Endocrine Society.

Conventional treatment of familial hypophosphatemia relies on oral phosphate salts and active vitamin D, which may worsen hypophosphatemia and cause hypercalcemia, nephrocalcinosis, and hyperparathyroidism. Despite the recent Food and Drug Administration (FDA) approval of the antibody burosumab, its accessibility remains limited. Moreover, the health care resource burden of hypophosphatemia remains unclear, which makes it challenging to determine the cost-benefit ratio of expanded use of burosumab.

To examine the real-world clinical and health care resource burden of familial hypophosphatemia, researchers conducted a retrospective observational cohort study by using MarketScan claims data from 2017 through 2021. Inclusion criteria were burosumab-naïve pediatric and adult patients with at least 1 diagnosis code for hypophosphatemia and matched control participants without the condition.

The researchers compared patient characteristics at baseline and disease characteristics, HCRU, and costs during 12 months of follow-up between patients with and without hypophosphatemia. Subgroup analyses stratified by age group were also conducted.

The study included 570 participants with hypophosphatemia and 1710 matched control participants. Roughly 10% of study participants were younger than 18 years of age and 57.0% of participants were female.

Participants with vs without hypophosphatemia had a 7.8-fold higher mean baseline Charlson Comorbidity Index and a higher prevalence of comorbidities such as kidney disease (33% vs 3%), arthralgia (25% vs 10%), and osteoarthritis (17% vs 6%; P <.001) during follow-up.

During follow-up, all-cause HCRU was statistically significantly greater for participants with hypophosphatemia than control participants for in-patient admission (60% vs 4%), out-patient emergency room visits (51.6% vs 15.7%), and out-patient pharmacy prescriptions (96% vs 71%; P <.001).

The mean annual total health care cost per participant was 22.6-fold greater among those with familial hypophosphatemia than control participants (adjusted cost difference, $129,643 (P<.001).

These between-group differences were observed across all age groups.

Study limitations include a lack of generalizability to patients without health care coverage, the absence of data on race, and the exclusion of patients who took burosumab.

The researchers concluded, “Patients with familial hypophosphatemia had a greater clinical burden than matched controls, including baseline Charleston Comorbidity Index score and medication use and morbidities including renal disease, over the 12-month follow-up period. All-cause HCRU and costs were substantially and significantly greater for patients with hypophosphatemia compared with controls.”

Disclosure: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.