Criteria for classification from the American College of Rheumatology consist of the following: Asthma Eosinophilia of > 10% in peripheral blood Paranasal sinusitis Pulmonary infiltrates, sometimes transient Histologic evidence of vasculitis with extravascular eosinophils Multiple mononeuropathy or polyneuropathy If ≥ 4 criteria are present, sensitivity is 85%, and specificity is 99.7%.