Clinical features and prognosis of microscopic polyangiitis with pulmonary involvement

Abstract:

Objective To investigate the clinical features and prognostic factors of microscopic polyangiitis（MPA） with pulmonary involvement.Methods A retrospective analysis was performed for the clinical data of 237 MPA patients with pulmonary involvement who were diagnosed and followed up till March 1，2021 in The First Affiliated Hospital of Chongqing Medical University from January 1， 2014 to March 1， 2021. The Kaplan-Meier method and the Cox proportional-hazards regression model were used to analyze survival data and obtain cumulative survival rate and prognostic factors.Results The MPA patients with pulmonary involvement had a mean age of 65.18 years and a median follow-up time of 26.13 months. Among the 237 patients enrolled in this study，98（41.35%） had MPA with diffuse alveolar hemorrhage（DAH）. The 1-，3-，and 5-year cumulative survival rates were 67.50%， 54.10%， and 43.00%，respectively，for the MPA patients with pulmonary involvement， with a median survival time of 45.03 （0.10， 97.73） months. The 1-， 3-，and 5-year cumulative survival rates were 63.30%，49.40%，and 40.20%，respectively，for the patients with MPA with DAH. The multivariate Cox regression analysis showed that age>65 years［hazard ratio（HR）=1.981，95%CI=1.244-3.154，P=0.004］，white blood cell count（WBC）>10×10⁹/L（HR=1.860，95%CI=1.170-2.956，P=0.009），serum creatinine（SCr）>250 μmol/L（HR=1.987，95%CI=1.217-3.243，P=0.006），PaO₂/FiO₂<300 mmHg（HR=2.780，95%CI=1.696-4.557，P<0.001），and Birmingham vasculitis activity score version 3（BVASv.3） at the time of diagnosis（HR=1.040，95%CI=1.006-1.075，P=0.020） were independent influencing factors for survival time（P<0.05）.Conclusion MPA patients with pulmonary involvement tend to have a low survival rate. Age>65 years，WBC>10×10⁹/L，SCr>250 μmol/L， PaO₂/FiO₂<300 mmHg， and BVASv.3 at the time of diagnosis are independent risk factors for the poor prognosis of MPA with pulmonary involvement.