Emergency testing for antineutrophil cytoplasmic antibodies combined with a dialog-based policy between clinician and biologist: effectiveness for the diagnosis of ANCA-associated vasculitis.

Abstract

A prompt immunosuppressive treatment initiation is crucial in ANCA-associated vasculitis (AAV) to minimize organ injury. The aim of the present work was to analyze the accuracy of emergency ANCA screening to identify rapidly patients with AAV. In our Institution, emergency ANCA screening is based on a telephone call between a Clinician and a Biologist. Indirect immunofluorescence (IIF) for ANCA detection was performed using a commercial kit (Euroimmun(®) Granulocyte Mosaic 12). Positive serums for c- or p-ANCA at IIF are subsequently screened for antigenic specificity (MPO or PR3) by an immunodot technique (immunodot, D-Tek(®).) Positive samples with atypical c- or p-ANCA pattern at IIF are subsequently screened for antigenic specificity by ELISA. Data were retrieved from patients' medical records and confronted to emergency ANCA screening results. Between 2005 and 2012, 114 patients were screened. IIF was positive in 27.2% of patients, but c-/p-ANCA anti-MPO/-PR3 was detected in 13.2% of patients. The sensibility and specificity of IIF combined with immunodot for newly diagnosed AAV were 83.3 and 100%, respectively. Ten patients were newly diagnosed with AAV. In these patients, a specific AAV treatment was initiated less than 24 h following ANCA screening. Emergency ANCA screening based on a clinical gating policy was relevant to identify patients with AAV diagnosis, and was associated with a rapid treatment initiation.