The calculator in question is the ACR/EULAR (American College of Rheumatology/European League Against Rheumatism) Classification Criteria for Eosinophilic Granulomatosis with Polyangiitis (EGPA). This scoring system is used in the clinical setting to classify patients with suspected EGPA, a rare autoimmune disease characterized by inflammation of small to medium-sized blood vessels, and a high number of eosinophils, a type of white blood cell.

The ACR/EULAR criteria for EGPA are applicable to patients who present with symptoms suggestive of vasculitis, particularly those with a history of asthma, sinusitis, transient pulmonary infiltrates, and peripheral eosinophilia. The criteria include six items: asthma, eosinophilia >10%, neuropathy, non-fixed pulmonary infiltrates, paranasal sinus abnormality, and biopsy containing a blood vessel with extravascular eosinophils. 

The clinical utility of this calculator is to aid in the diagnosis of EGPA, which can be challenging due to its rarity and the wide range of clinical presentations. The ACR/EULAR criteria for EGPA can help clinicians differentiate EGPA from other types of vasculitis and guide appropriate treatment.

There are no specific exclusion criteria for the use of the ACR

ACR/EULAR classification criteria for eosinophilic granulomatosis with polyangiitis

# Criteria
 # Entry criteria
A. Evidence of small- or medium-vessel vasculitis on imaging (+20)
B. Alternative diagnoses mimicking vasculitis are excluded (+20)
# Clinical criteria
C. Obstructive airway disease (+3)
D. Nasal polyps (+3)
E. Mononeuritis multiplex (+1)
# Laboratory and biopsy criteria
F. Blood eosinophil count >= 1×10**9/L (+5)
G. Extravascular eosinophilic-predominant inflammation on biopsy (+2)
H. Positive test for cytoplasmic antineutrophil cytoplasmic antibodies or anti-proteinase 3 antibodies (-3)
I. Hematuria (-1)

# Conditions
- score >= 46
- true
- score == 0

2022 American College of Rheumatology / European Alliance of Associations for Rheumatology Classification Criteria for Eosinophilic Granulomatosis with Polyangiitis.