Renal function and ear, nose, throat involvement in anti-neutrophil cytoplasmic antibody-associated vasculitis: Prospective data from the European Vasculitis Society clinical trials

Objective: We investigated whether ENT involvement is associated with renal biopsy findings and renal function in patients with ANCA-associated vasculitis (AAV). Methods: Newly diagnosed AAV patients derived from three international, multicentre trials were included. To investigate an association between ENT involvement and estimated glomerular filtration rate (eGFR) at diagnosis and 5-year follow-up, we performed multivariable regression analyses including clinical and histopathological parameters. To investigate whether our findings are specific to ENT involvement, we performed comparable analyses between eGFR and other early disease manifestations (arthralgia/arthritis, cutaneous and lung involvement). Results: One hundred and eighty-five of the 414 patients had ENT involvement. The mean presenting eGFR of patients with and without ENT involvement was 39.16 and 23.88 ml/min/1.73m², respectively (P<0.001). Mean eGFR increased by 6.76 ml/min/1.73m² with each added ENT symptom (P = 0.007). Patients with ENT involvement had less interstitial fibrosis and tubular atrophy and a prognostically more favourable histopathological class on renal biopsy examination. Multivariable regression analyses correcting for clinical and histopathological parameters showed that ENT involvement is associated with both baseline and 5-year follow-up eGFR. There were no associations between baseline and 5-year follow-up eGFR and arthralgia/arthritis, cutaneous or lung involvement, suggesting that our findings are specific to ENT involvement. Conclusion: The presence of ENT involvement in AAV patients is associated with prognostically favourable renal biopsy findings and better renal function. These results indicate that there may be different phenotypes of AAV defined by ENT involvement.