Churg-Strauss syndrome, now also referred to by its medically more accurate term eosinophilic granulomatosis with polyangiitis (EGPA), is a rare systemic vasculitis (inflammation in the wall of blood vessels of the body), predominantly affecting small-sized vessels. Because antineutrophil cytoplasmic auto-antibodies (ANCA) can be detected in the serum (liquid and acellular part of the blood) in up to 40% of the patients, it is also considered one of the three ANCA-associated vasculitides, along with granulomatosis with polyangiitis (GPA/Wegener’s) and microscopic polyangiitis. However, the clinical characteristics and outcomes of these 3 vasculitides differ noticeably.
Main clinical characteristics of EGPA (Churg-Strauss) include late-onset allergic rhinitis and asthma, increased blood eosinophil count (a type of white blood cells usually implicated in allergy and defense against certain parasitic infections) and vasculitis manifestations, some of which can be life-threatening. Mechanisms of the disease are complex and not completely elucidated, but treatment is well standardized, and the majority of patients respond well to therapy. Long-term corticosteroid therapy is frequently needed because of persistent asthma.
What is EGPA (Churg-Strauss)?
EGPA (Churg-Strauss) is one of the rarest systemic vasculitis, with less than 2 people in a million population being diagnosed each year. The main disease features include late-onset asthma, blood eosinophilia and vasculitis manifestations such as skin nodules or purpura (skin rash of punctuated red lesions) and mononeuritis multiplex (causing numbness or tingling or sudden loss of strength in the hands or feet). Cardiac involvement is also frequent and important to diagnose because it can be potentially severe and life-threatening.
The cause of this disease is unknown. Most patient have asthma, often with an allergic component as well as nasal polyps. In few cases, exposure to some environmental inhaled allergens, vaccinations, desensitization or drugs (like leukotriene receptor antagonists used for treating asthma) have been incriminated as potential triggers or precipitating factors for EGPA (Churg Strauss) onset or flares.
Who gets EGPA (Churg-Strauss) and how common is it?
People around the age of 50 years are most affected. The disease can occur at any age, although very rarely in childhood. There is no sex preponderance and there is no strong evidence of a difference in occurance of the disease around the globe, at least between European and North American countries, where EGPA (Churg-Strauss) currently affects about 10 to 15 living patients in a million population.
EGPA (Churg-Strauss) predominantly affects the small-sized arteries in the body. The symptoms depend on which organs are affected and to which extent. Thus, symptoms vary from one person to another and not all symptoms are present in everyone at the time of diagnosis or during the course of the disease. However, almost all patients have asthma and/or nasal sinus polyps and blood eosinophilia. Of note, eosinophilia is relatively frequent in patients with common allergic asthma even when a patient does not have EGPA (Churg-Strauss). Other features of this disease can include:
- Rapid and sudden weight loss
- Muscle and joint pain
- Skin rash (purpura, subcutaneous nodules or recurrent and diffuse hives)
- Numbness or tingling of the hands or feet
- Sudden loss of strength in the hands or feet
- Chest pain or palpitations (unpleasant awareness of your own heartbeat, which can be irregular)
- Increasing shortness of breath or coughing (not improving with conventional anti-asthma drugs)
- Venous thrombotic events (phlebitis or pulmonary embolism)
- Abdominal pain
- Presence of blood in the stools
The diagnosis of EGPA (Churg-Strauss) is based on the combination of symptoms, physical examination, laboratory tests, specialized imaging studies and, when possible, a biopsy of an affected tissue or organ to demonstrate the typical features of EGPA. vasculitis. The presence of blood eosinophilia is suggestive of EGPA but by itself is not enough to diagnose this disease. Many other conditions can cause blood eosinophilia, such as allergy, some parasitic infections or primary blood disorders (named primary hypereosinophilic syndrome or neoplasms). In some patients, the detection in the serum of antineutrophil cytoplasmic auto-antibodies (ANCA) can also support the diagnosis.
Treatment and Side Effects
Patients without severe vasculitis manifestations (that is, if there is no vasculitis-related cerebral, cardiac, renal or gastrointestinal involvement) can initially be treated with corticosteroids alone. More than 90% of such patients will achieve remission, but one-third may experience relapses and thus require the addition of another drug. Patients with severe manifestations are generally treated with a combination of corticosteroids and an immunosuppressant drug, such as cyclophosphamide, methotrexate or azathioprine, depending on the clinical situation. Frequently a combination of corticosteroids and cyclophosphamide are used for the first three to six months, and thereafter the cyclophosphamide is switched to methotrexate or azathioprine for maintenance for several additional months.
The prognosis for patients with EGPA (Churg-Strauss) has improved dramatically within the past 3 decades although there is still no cure. More than 90% of the patients will achieve remission, with disappearance of active clinical symptoms. However, vasculitis relapse occur in up to 35% of the patients. Asthma, which is not considered to be directly due to the vasculitis, persists in more than 70% of patients even when the vasculitis is not active. Thus, patients may require continuing low doses of prednisone and/or inhaled corticosteroids for several months or years.
What are the complications?
Cardiac involvement represents the main potential and initial complication of EGPA (Churg-Strauss), along with treatment-induced adverse events, especially infections. Besides persistent asthma in most of the patients in remission, vasculitic peripheral neuropathy can cause damage and long-lasting numbness or decreased sensitivity in feet or hands. In the long term, congestive heart failure and other cardiovascular complications due to long-term treatments or cardiac vasculitis involvement, can also occur. Comprehensive and long term follow-up is necessary.
Monitoring the disease
Patients require close and prolonged follow-up with their doctors with periodic monitoring of the disease activity which is done based on symptoms and laboratory evaluations. In addition to monitoring for disease relapses, patients also need to be monitored for problems related to asthma, organ damage due to vasculitis, cardiovascular status and treatment related side effects.
Blood eosinophil count and parameters of inflammation (sedimentation rate or C reactive protein) are among the tests ordered on a regular basis to monitor disease activity. However, these test results should be interpreted cautiously because they can be altered in several other conditions (allergies, infections etc).
What’s new in EGPA (Churg-Strauss)?
Long term follow up of groups of patients with EGPA (Churg-Strauss) have provided valuable information on the prognosis of the disease and long-term complications of therapy. Clinical trials through multi-center and international collaborations are providing insights on how to treat this disease, and reduce the need for corticosteroids. A better understanding of the causes of this disease may help to develop better and safer therapeutic strategies and identify reliable biomarkers for the follow-up of the patients over time.
Revision: September 2012