LONG-TERM OBSERVATIONAL STUDY OF INTERSTITIAL LUNG DISEASE IN ANCA-ASSOCIATED VASCULITIS
Authors: David Jayne et al.
That Interstitial Lung Disease (ILD) may be an early disease manifestation of ANCA-associated Vasculitis (AAV) was first published in 2010. All patients of the initial report showed renal involvement. Still, there is limited data on the epidemiology and long-term outcome of ILD patients with conflicting results regarding the effectiveness of the immunosuppressive treatment.
This study reports about 1002 patients with AAV or ANCA-associated ILD. CTs of ILD patients showed UIP, NSIP, organising pneumonia or chronic hypersensitivity pneumonia. The occurrence of ILD was compared with the presence and histology of nephritis, focusing on fibrotic phenotypes and assessed the impact of immunosuppressive therapy on the rate of evolution of FVC% and TLCOc% between treatment initiation (T0) and 12(±3) months (T12). 54 patients had microscopic polyangiitis (MPA), 15 had granulomatosis with polyangiitis (GPA) and 20 had ANCA positive ILD without vasculitis (ANCA-ILD). The total prevalence of ILD was 8.9% (n=89) with mean age 69.2±10.8 years and MPO positivity in 82%. The median survival was 10 years; the survival with UIP (n=66) was worse compared to non-UIP (n=23) (log-rank, p=0.04). Patients with AAV-ILD and renal involvement (n=47) had better kidney function and lower proteinuria at diagnosis compared to those with nephritis without ILD (n=186) (mean eGFR 41.87 vs 29.6 ml/min/1.73m2, p=0.007). FVC% at baseline was an independent risk factor for respiratory failure (oxygen requirement) [HR 0.94 CI 95% (0.892-0.994), p=0.030]. When evaluating the impact of immunosuppression on lung progression over 12 months (cyclophosphamide, CYC, n=30; rituximab, RTX, n=25; mycophenolate, MMF, n=8), higher increase of FVC% and lower decline of TLOCc% were reported in the CYC compared to the RTX groups [mean difference: FVC%= -2.49, 95% CI (-10.06 to 5.07), TLCOc=-11.25, 95% CI (-33.08 to 10.58)].
Taken together this study confirms a prognostic impact of fibrotic phenotype (UIP with worst prognosis) and initial FVC. It shows that in this phenotype of AAV, the lung has a higher impact on outcome than the kidney. Furthermore, a better response to CYC than RTX is reported. Collectively, it underlines the need of multidisciplinary approach in AAV.