Red flags for clinical suspicion of eosinophilic granulomatosis with polyangiitis (EGPA).

Background: Eosinophilic granulomatosis with polyangiitis (EGPA), is a rare ANCA-associated systemic vasculitis. Its overlapping features with other vasculitic or eosinophilic diseases, and the wide and heterogeneous range of clinical manifestations, often result in a delay to diagnosis.

Objective: To identify red flags that raise a suspicion of EGPA to prompt diagnostic testing and to present an evidence-based clinical checklist tool for use in routine clinical practice.

Methods: Systematic literature review and expert consensus to identify a list of red flags based on clinical judgement. GRADE applied to generate a strength of recommendation for each red flag and to develop a checklist tool.

Results: 86 studies were included. 40 red flags were identified as relevant to raise a suspicion of EGPA and assessed by the experts as being clinically significant. Experts agreed that a diagnosis of EGPA should be considered in a patient aged ≥6 years with a blood eosinophil level >1000 cells/µL if untreated and >500 cells/µL if previously treated with any medication likely to have altered the blood eosinophil count. The presence of asthma and/or nasal polyposis should reinforce a suspicion of EGPA. Red flags of asthma, lung infiltrates, pericarditis, cardiomyopathy, polyneuropathy, biopsy with inflammatory eosinophilic infiltrates, palpable purpura, digital ischaemia and ANCA positivity, usually anti-myeloperoxidase, among others, were identified.

Conclusion: The identification of a comprehensive set of red flags could be used to raise a suspicion of EGPA in patients with eosinophilia, providing clinicians with an evidence-based checklist tool that can be integrated into their practice.