A comparative analysis of different biofluids using Raman spectroscopy to determine disease activity in ANCA ‐associated vasculitis

Abstract

Identifying persistent or relapsing disease in anti‐neutrophil cytoplasmic autoantibody (ANCA) associated vasculitis (AAV) remains a clinical challenge with an unmet need for a reliable biomarker of multisystem disease. In this study we confirm for the first time that Raman spectroscopy offers a novel cost‐effective candidate biomarker to discriminate active disease from remission in AAV with excellent accuracy. Spectrochemical interrogation of plasma and serum samples demonstrated equal ability to discriminate disease activity with good group separation on PC1 direction and a high degree of accuracy on validation testing using blind predictive modelling: F‐score 80% for plasma (specificity 93.3%, sensitivity 70%, AUC 0.95) and 80% for serum (specificity 80%, sensitivity 80%, AUC 0.92). Similar findings were seen on analysis of paired remission samples following successful remission‐induction therapy. A larger study with longitudinal data is required to validate these findings with the potential to aid patient care.