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EOSINOPHILIC GRANULOMATOSIS WITH POLYANGIITIS (EGPA) OVERVIEW

  • DISEASE PROFILE

    THE BASICS OF EGPA

    Description

    The Chapel Hill Consensus Conference (CHCC)—a committee of clinicians and pathologists—renamed Churg-Strauss syndrome as EGPA in 2012. The CHCC defines EGPA as an eosinophil-rich and necrotizing granulomatous inflammation often involving the respiratory tract and necrotizing vasculitis predominantly affecting small to medium vessels. Patients often have asthma, sinusitis, and pulmonary infiltrates.1-3

    Prevalence and onset

    Based on global estimates, EGPA likely affects approximately 5,000 people in the United States.4,5* The average age range for onset is between 40 and 60 years old. However, onset can occur prior to age 40.6,7 It may take a while to diagnose EGPA. The average time between disease onset and diagnosis is approximately 49.7 months (±6.1 months).7

    Disease phases

    EGPA is classically described as a 3-phase disorder; however, these 3 phases do not necessarily have to follow one another and may overlap. Patients may not experience all phases6,8,9:

    1. PRODROMAL (ALLERGIC)
    Adult onset asthma is the main manifestation, but this phase may also include rhinosinusitis and growths in the nose
    2. EOSINOPHILIC
    Higher levels of eosinophils are found in the blood or tissues during this phase. For example, the heart and gastrointestinal tract may be affected
    3. VASCULITIC
    Severe blood vessel inflammation (vasculitis) can reduce blood flow to organs and tissues. For example, the nervous system and skin may be affected

    The mean latency between the onset of the prodromal phase and the vasculitic phase is estimated to be between 3 and 9 years.2

    Goal of treatment

    The current standard of care (SOC) is oral corticosteroids (OCS) with or without an immunosuppressant. According to EGPA guidelines, the goal of therapy in EGPA is to increase remission and reduce relapse rates while tapering OCS dose.10

    *The US estimate is derived from a global summary prevalence of 14.58 cases per million, based on a US population of approximately 325 million people as of July 2017.4,5

     

  • SELECT CLINICAL MANIFESTATIONS

    CLINICAL MANIFESTATIONS CAN VARY FROM PATIENT TO PATIENT

    Below are the organ domains that may be affected by EGPA8:

    Image of affected organ domains
  • CLASSIFICATION AND DIAGNOSTIC EVALUATIONS

    CLASSIFICATION CRITERIA

    American College of Rheumatology criteria

    The 1990 American College of Rheumatology criteria were established for classification, and not diagnostic, purposes for patients with vasculitis. The presence of at least 4 of the 6 criteria below yields a sensitivity of 85% and a specificity of 99.7% for the classification of EGPA.3,6

    These criteria include3:

    1. Asthma
    2. Eosinophilia (>10% of total white blood cells)
    3. Neuropathy (mono- or poly-)
    4. Non-fixed pulmonary infiltrates
    5. Paranasal sinus abnormalities
    6. Extravascular eosinophilic infiltration on biopsy
    4 of 6 Criteria

    POSSIBLE DIAGNOSTIC EVALUATIONS

    Laboratory and imaging tests (based on patient presentation)

    • Complete blood count (CBC) with differential to evaluate eosinophil count9
    • Urinalysis10
    • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level11
    • Pulmonary function tests10
    • Electromyography and nerve-conduction studies10
    • Electrocardiogram, N-terminal probrain natriuretic peptide (NT-proBNP), and troponin I measurements10
    • CT scans, MRI, ultrasound as needed10

    ANCA detection

    EGPA is an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. ANCA positivity is observed in up to 40% of patients with EGPA.10,12

    • A combination of immunofluorescence and enzyme-linked immunosorbent assays (ELISA) is used to maximize sensitivity and specificity for diagnosis13
    • ANCA positivity is suggestive of the disease in the appropriate clinical setting, but ANCA negativity does not rule out the disease10
    • Some data suggest there are different EGPA phenotypes based on ANCA status; however, more study is needed14,15

    Biopsy

    • Although biopsy is the gold standard, most patients do not undergo biopsy and are diagnosed on a clinical basis10,12
    • While skin, nerve, and muscle are among the tissues most often biopsied, endomyocardial, renal, and gastrointestinal biopsies may be useful as well10
    • A biopsy containing a blood vessel with extravascular eosinophils supports a diagnosis in the context of other clinical manifestations of EGPA10

References: 1. Jennette JC, Falk RJ, Bacon A, et al. 2012 Revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. Arthritis Rheum. 2013;65(1):1-11. 2. Latorre M, Baldini C, Seccia V, et al. Asthma control and airway inflammation in patients with eosinophilic granulomatosis with polyangiitis. J Allergy Clin Immunol Pract. 2016;4(3):512-519. 3. Masi AT, Hunder GG, Lie JT, et al. The American College of Rheumatology 1990 criteria for the classification of Churg-Strauss syndrome (allergic granulomatosis and angiitis). Arthritis Rheum. 1990;33(8):1094-1100. 4. Annual Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico: April 1, 2010 to July 1, 2017. U.S. Census Bureau, Population Division. Accessed January 18, 2018. 5. Data on file, GSK. 6. Vaglio A, Buzio C, Zwerina J. Eosinopilic granulomatosis with polyangiitis (Churg-Strass): state of the art. Allergy. 2013;68(3):261-273. 7. Moosig F, Bremer JP, Hellmich B, et al. A vasculitis centre based management strategy leads to improved outcome in eosinophilic granulomatosis and polyangiitis (Churg-Strauss, EGPA): monocentric experiences in 150 patients. Ann Rheum Dis. 2013;72(6):1011-1017. 8. Baldini C, Talarico R, Della Rossa A, Bombardieri S. Clinical manifestations and treatment of Churg-Strauss syndrome. Rheum Dis Clin North Am. 2010;36(3):527-543. 9. Noth I, Strek ME, Leff AR. Churg-Strauss syndrome. Lancet. 2003;361(9357):587-594. 10. Groh M, Pagnoux C, Baldini C, et al. Eosinophilic granulomatosis with polyangiitis (Churg–Strauss) (EGPA) Consensus Task Force recommendations for evaluation and management. Eur J Intern Med. 2015;26(7):545-553. 11. Pagnoux C. Updates in ANCA-associated vasculitis. Eur J Rheumatol. 2016;3(3):122-133. 12. Comarmond C, Pagnoux C, Khellaf M, et al. Eosinophilic granulomatosis with polyangiitis (Churg-Strauss): clinical characteristics and long-term followup of the 383 patients enrolled in the French Vasculitis Study Group cohort. Arthritis Rheum. 2013;65(1):270-281. 13. Hagen EC, Daha MR, Hermans J, et al. Diagnostic value of standardized assays for anti-neutrophil cytoplasmic antibodies in idiopathic systemic vasculitis. EC/BCR Project for ANCA Assay Standardization. Kidney Int. 1998;53(3):743-753. 14. Sablé-Fourtassou R, Cohen P, Mahr A, et al. Antineutrophil cytoplasmic antibodies and the Churg-Strauss syndrome. Ann Intern Med. 2005;143(9):632-638. 15. Sinico RA, Di Toma L, Maggiore U, et al. Prevalence and clinical significance of antineutrophil cytoplasmic antibodies in Churg-Strauss syndrome. Arthritis Rheum. 2005;52(9):2926-2935.