[Clinical features and survival analysis of microscopic polyangiitis-associated interstitial lung disease:a retrospective study of 28 patients].

To explore the clinical features, laboratory examination and imaging features of microscopic polyangiitis (MPA)-associated interstitial lung disease (ILD), and to perform survival analysis. The records of 28 patients with MPA-ILD who were treated at the Affiliated Hospital of Medical School of Ningbo University were reviewed retrospectively from August 2014 to November 2021. The patients' clinical features, laboratory parameters, pulmonary function test, echocardiography, chest CT scan findings and therapeutic regimen were analyzed, and the relevant data were statistically analyzed. There were 18 males and 10 females, with an average age of (70.1±9.3) years. Among them, 13 patients had a history of smoking. The main clinical manifestations were cough (14/28), fever (12/28), chest tightness, shortness of breath (12/28) and hemoptysis (3/28). Sixteen patients had renal involvement, and 78.57% (22/28) and 89.28% (25/28) of the patients had elevated C-reactive protein (CRP) and ESR respectively. Sixteen (16/28) patients had increased rheumatoid factor (RF), and the positive rate of myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) was 82.12% (23/28). 96.43% (27/28) of ILDs were diagnosed before or at the same time as MPA. The chest radiological pattern was mainly usual interstitial pneumonia (UIP) or UIP-like (15/28), followed by nonspecific interstitial pneumonia (NSIP) (8/28). Compared with non-UIP-like patients, UIP or UIP-like patients were older (=0.018), and had higher serum LDH level (=0.041), but serum creatinine level was significantly lower (=0.041). Univariate and multivariate survival analysis showed that inappropriate treatment (=9.81, 95%: 1.68-57.29, =0.011) and elevated serum LDH (=4.11, 95%: 0.99-17.00, =0.051) were independent risk factors for shortened survival of MPA-ILD, while elevated RF (=0.22, 95%: 0.06-0.91, =0.037) was a protective factor for prolonged survival. MPA-ILD patients had fewer systemic vasculitis symptoms. Most of the ILD patients were diagnosed before or at the same time as MPA. The chest radiological pattern was mainly UIP or UIP-like, followed by NSIP. Early use of glucocorticoids combined with immunosuppressant or rituximab could improve the survival rate of MPA-ILD. The elevated serum LDH was an independent risk factor for shortened survival of MPA-ILD, while elevated RF was a protective factor for prolonged survival.