Clinical characteristics and prognostic factors for MPO-ANCA positive interstitial lung disease: A comparative study of ANCA associated vasculitis (AAV)-ILD and pulmonary limited vasculitis

Introduction

Microscopic polyangiitis (MPA) with interstitial lung disease (ILD) has a significant impact on morbidity and mortality. This study evaluated the clinical characteristics, treatment responses, and prognostic factors of patients with ANCA-associated vasculitis with ILD (AAV-ILD) and pulmonary limited vasculitis (PLV).

Patients and methods

A retrospective chart review of ILD patients positive for MPO-ANCA was conducted from 2008 to 2021. Patients were classified into AAV-ILD or PLV groups. Data included laboratory test results, pulmonary function tests, and high-resolution computed tomography (HRCT) images. Statistical analyses were used to assess group differences and survival outcomes.

Results

Of 114 patients, 80 were diagnosed with PLV and 34 with AAV-ILD. The AAV-ILD group had higher corticosteroid treatment rates, higher serum creatinine levels, and better survival than the PLV group. The PLV group had higher KL-6 levels, lower %VC and % FVC in pulmonary function tests. Survival in the PLV group was significantly worse than that in the AAV-ILD group, and survival of patients with an alternative diagnosis on HRCT was better than that of patients with a UIP pattern. Cox regression analysis identified a diagnosis of MPA and HRCT classification as significant prognostic factors.

Conclusions

Patients with AAV-ILD had a better prognosis than those with PLV. HRCT patterns, particularly an alternative diagnosis on HRCT, were associated significantly with a favourable prognosis. The efficacy of corticosteroid treatment in PLV patients was limited. These findings highlight the importance of early and accurate diagnosis, as well as careful consideration of treatment strategies, for patients with in MPO-ANCA-positive ILD.