How are patients with coexisting Giant Cell Arteritis (GCA) and myeloproliferative disorders managed?

From the Guidelines

Management of patients with coexisting Giant Cell Arteritis (GCA) and myeloproliferative disorders requires a coordinated approach addressing both conditions simultaneously, with initial treatment typically involving high-dose corticosteroids and potential addition of steroid-sparing agents like tocilizumab, alongside management of the myeloproliferative disorder. The treatment strategy should prioritize controlling arterial inflammation while managing blood cell proliferation, with careful attention to potential drug interactions and cumulative toxicities from multiple medications 1.

Key Considerations

• Initial treatment with high-dose corticosteroids (prednisone 40-60 mg daily) is crucial to rapidly control GCA inflammation and prevent vision loss, with gradual tapering over 12-24 months based on clinical response and inflammatory markers.
• For steroid-sparing, tocilizumab (162 mg subcutaneously weekly or every other week) can be added, which has shown efficacy in maintaining remission while reducing steroid exposure 1.
• The myeloproliferative disorder management depends on the specific type but may include cytoreductive therapy such as hydroxyurea, ruxolitinib for myelofibrosis, or phlebotomy for polycythemia vera to maintain hematocrit below 45% 1.
• Low-dose aspirin (81-100 mg daily) is typically used to reduce thrombotic risk in both conditions.

Monitoring and Adjustment

• Regular monitoring is essential, including complete blood counts, inflammatory markers (ESR, CRP), liver function tests, and clinical assessments for symptoms of both conditions.
• The treatment approach must be adjusted based on the patient's response, with careful consideration of the potential for drug interactions and cumulative toxicities from multiple medications 1.

Recent Guidelines

• The 2018 EULAR recommendations for the management of large vessel vasculitis provide a framework for the treatment of GCA, including the use of glucocorticoids and steroid-sparing agents like tocilizumab 1.
• The 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of giant cell arteritis and Takayasu arteritis also provides recommendations for the management of GCA, including the use of immunosuppressive therapy and surgical intervention in certain cases 1.

From the Research

Management of Coexisting GCA and Myeloproliferative Disorders

• The management of patients with coexisting Giant Cell Arteritis (GCA) and myeloproliferative disorders is complex and requires careful consideration of the treatment options for both conditions 2.
• Glucocorticoids remain the mainstay of treatment for GCA, with an initial dose of 40-60 mg/day of prednisone usually adequate 3, 4.
• In patients with myeloproliferative disorders, the treatment of GCA may need to be tailored to avoid exacerbating the underlying condition 2.
• Methotrexate has been shown to be effective as a glucocorticoid-sparing agent in patients with GCA, and may be considered in patients with myeloproliferative disorders 5.
• The use of low-dose aspirin may also be beneficial in reducing the risk of cranial ischemic complications secondary to GCA 3, 4.

Treatment Outcomes

• Patients with coexisting GCA and myeloproliferative disorders may have a distinct clinical phenotype and poorer outcome, with a higher risk of steroid dependence and relapse 2.
• The relapse-free and steroid-free survivals were significantly decreased in patients with GCA and myeloproliferative disorders compared to those with idiopathic GCA 2.
• However, the overall survival was not significantly different between the two groups 2.

Clinical Considerations

• The diagnosis of GCA in patients with myeloproliferative disorders requires careful consideration of the clinical presentation and laboratory findings 2.
• The treatment of GCA in patients with myeloproliferative disorders should be individualized, taking into account the specific needs and risks of each patient 4, 2.
• Regular monitoring for corticosteroid-associated side effects, relapses, and flare-ups is essential in the management of patients with coexisting GCA and myeloproliferative disorders 6.