Is continuation of Xolair (omalizumab) injection, diagnosis code D47.02, from 3/24/25 to 6/30/25, medically necessary?

Medical Necessity Determination: Continuation of Xolair for Systemic Mastocytosis

Primary Determination

No, continuation of Xolair (omalizumab) from 3/24/25 to 6/30/25 was NOT medically necessary based on the clinical documentation provided, as the patient does not meet diagnostic criteria for systemic mastocytosis (D47.02) and shows evidence of worsening symptoms despite treatment escalation.

Critical Diagnostic Discrepancy

The fundamental issue is diagnostic misclassification. The patient carries a diagnosis code of D47.02 (systemic mastocytosis), but the clinical documentation explicitly states "Idiopathic Mast Cell Activation Syndrome (MCAS), diagnosed in 2020" with bone marrow biopsy from April 2021 showing "no mastocytosis" 1. This is a critical distinction because:

• Bone marrow biopsy showed no evidence of mastocytosis, with flow cytometry revealing no mast cell disorders and negative KIT mutation analysis 1
• The patient has MCAS, not systemic mastocytosis, which are distinct clinical entities with different diagnostic criteria and treatment paradigms 1
• Insurance criteria specifically require meeting major and minor diagnostic criteria for systemic mastocytosis (Appendix B criteria), which this patient objectively fails to meet 1

Evidence of Treatment Failure

The clinical trajectory demonstrates progressive symptom worsening despite aggressive treatment escalation:

• Dose escalation from 450mg to 600mg every 2 weeks on 1/13/25 has not controlled symptoms 1
• The 4/7/25 note explicitly states: "Overall trajectory is for increasing symptoms in spite of recent medication changes of increased Xolair and re-introduction of cromolyn" 1
• Patient had 68 emergency department visits in 2024, indicating severe uncontrolled disease despite ongoing Xolair therapy 1
• Patient continues to report persistent nausea, worsening headaches, and symptoms with every bowel movement as of 4/7/25 1

Continuation Criteria Not Met

The insurance policy requires that continuation therapy patients "must meet all initial authorization criteria" 1. However:

• Initial approval criteria require documented systemic mastocytosis with specific diagnostic findings, which this patient lacks 1
• The clinical response does not demonstrate benefit—continuation of therapy should show improvement or stabilization, not progressive worsening 2
• Research evidence shows that continuation of omalizumab after long-term treatment should result in "improved symptom control and reduced exacerbation risk" 2, which is clearly not occurring in this case

Evidence-Based Considerations for Omalizumab Continuation

When omalizumab IS appropriately continued long-term:

• The XPORT study demonstrated that patients continuing omalizumab had 40.1% relative reduction in exacerbations compared to withdrawal 2
• Continuation should show maintained benefit with improved Asthma Control Test scores and reduced exacerbation rates 2
• Some patients maintain clinical improvement even after withdrawal following 6 years of treatment, with downregulation of basophil reactivity 3

Safety Monitoring Requirements

If Xolair were to be continued (which is not recommended based on lack of efficacy and wrong diagnosis), proper safety protocols must be followed:

• Patients must be observed for 2 hours after the first 3 injections and 30 minutes after subsequent injections 4, 5
• All patients must carry an epinephrine autoinjector, as anaphylaxis occurs in 0.09-0.2% of patients, with 75% of reactions occurring within 2 hours but some delayed up to 4 days 5, 1
• Anaphylaxis risk is higher in patients with prior history of anaphylaxis to foods or medications 1, which this patient has (documented idiopathic anaphylaxis)

Clinical Recommendation

The appropriate course of action is:

• Deny continuation based on incorrect diagnosis (MCAS coded as systemic mastocytosis) and failure to meet diagnostic criteria for the billed diagnosis 1
• Recommend comprehensive re-evaluation by the Massachusetts General Hospital allergist to confirm diagnosis and explore alternative therapeutic strategies for MCAS 1
• Consider alternative treatments for MCAS, as the current regimen including maximum-dose Xolair is clearly failing to control symptoms 1
• Document that 26 prior visits (3/14/24-2/24/25) plus the requested 8 visits represent substantial treatment duration without adequate response 1