This policy is designed to address medical guidelines that are appropriate for the majority of individuals with a particular disease, illness, or condition. Each person's unique clinical circumstances may warrant individual consideration, based on review of applicable medical records.

Burosumab (Crysvita) is considered medically necessary in adult and pediatric individuals one (1) year of age or older who meet ALL of the following:

• Diagnosis of XLH, verified by pathogenic mutation in PHEX; and
• Oral phosphate and active vitamin D analogs have been discontinued and will remain discontinued at least 7 days before and during ongoing treatment with burosumab (Crysvita); and
• Documentation of fasting serum phosphorus concentration below the reference range for age; and
• At least ONE of the following:
  • Documentation of low tubular resorption of phosphate corrected for glomerular filtration rate (TmP/GFR) based on age; or
  • Documentation of any of the following signs and symptoms of XLH including but not limited to growth retardation, bone fractures, musculoskeletal pain, dental abscesses, x-ray imaging showing deformities, or Thacher Rickets Severity Score (RSS), etc.

Continuation of therapy with burosumab (Crysvita) after twelve (12) months may be considered medically necessary for the treatment of an individual with documented diagnosis of XLH when the following criteria are met:

• Diagnosis of XLH; and
• Documentation of improved fasting serum phosphorus concentration in relation to age (doses should be held if serum phosphorus is above 5 mg/dL); and
• Documentation of improved TmP/GFR level if previously reported; and
• Documentation of improved signs and symptoms of XLH such as a lower score on the Thacher Rickets Severity Score (RSS).

The use of burosumab (Crysvita) is considered experimental/investigational and, therefore, non-covered for all other indications. Scientific literature does not support its use for other indications.

The administration of burosumab (Crysvita) is typically an outpatient procedure which is only eligible for coverage as an inpatient procedure in special circumstances, including, but not limited to, the presence of a co-morbid condition that would require monitoring in a more controlled environment such as the inpatient setting.

Services that do not meet the criteria of this policy will be considered experimental/investigational (E/I). A network provider can bill the member for the experimental/investigational service. The provider must give advance written notice informing the member that the service has been deemed E/I. The member must be provided with an estimate of the cost and the member must agree in writing to assume financial responsibility in advance of receiving the service. The signed agreement must be maintained in the provider’s records.

• Link to Provider Resource Center for the Medical Policy Update

8/2018 Clinical Guidelines Developed for Burosumab (Crysvita)

• Link to Diagnosis Codes

• Link to References