Clinical Features And Outcomes Of Microscopic Polyangitis

Background:Microscopic polyangitis (MPA) is systemic and necrotizing vasculitis, with no or few immune deposits, predominantly affecting small vessels. Granulomatous inflammation is not centered on vessels. There are differences in epidemiology, clinical features and laboratory findings between different regions. At present, there are some studies on clinical manifestations and prognosis of MPA in Europe, Japan and Korea, but few in China.Objective:To explore the clinical features and risk factors of survival in MPA patients.Methods:We retrospectively investigated the clinical data of patients hospitalized with MPA in Peking Union Medical College Hospital from January2007to December2012, the data included demographic characteristics, clinical manifestations, laboratory parameters, chest computed tomography (CT), pulmonary function test, arterial blood gas analysis, echocardiography, histopathology, disease activity scores (Five Factor Score and Birmingham Vasculitis Activity Score, treatment and outcomes.The risk factors of survival time were analyzed.Results:The191patients met the criteria for MPA were enrolled. Eighty-nine men and102women, with a mean (±SD) age of63.1±13.84(range17-85, median age66) years.Their main clinical symptoms were fever (73%), arthralgias (32%), myalgias (30%), renal manifestations (89%), lung involvement (77%), ear-nose-throat (ENT) involvement (20%), peripheral neuropathy (19%) and central nervous system involvement (9%). Pulmonary involvement was the initial manifestation in93patients,41%(38/93) had interstitial lung disease, and5cases were lung single-organ involvement. Respiratory symptoms related to pulmonary involvement preceded other disease manifestations by two weeks to17years. Perinuclear pattern antineutrophil cytoplasmic antibodies (p-ANCA) were present in179of191patients (93.7%), the prevalence of positive cytoplasmic pattern antineutrophil cytoplasmic antibodies (c-ANCA) was4.2%. Chest CT manifestations included ground glass attenuation, honeycombing, patchy shadow, traction bronchiectasis and pleural effusion et al. Pulmonary function tests showed that resitrictive ventilation dysfunction and reduced carbon monoxide diffusing capacity. Of the191patients,69died during followup. Pneumonia was the leading cause (55.1%). The patients had a median survival time of75months (95%CI49.907-100.093). Age (≥66years, P=0.002), BVAS (≥21, P=0.000), FFS (P=0.004), alveolar hemorrhage (P=0.007) and pulmonary infection (P=0.000) were associated with higer mortality. COX multivariate regression analysis revealed that age (HR1.051,95%CI1.023-1.079, P=0.000), BVAS (HR1.094,95%CI1.064-1.126, P=0.000), alveolar hemorrhage (HR2.570,95%CI1.481-4.458, P=0.001) and pulmonary infection (HR1.399,95%CI1.042-1.879, P=0.025) were the risk factors of survival.Conclusion:Lung involvement could present before the time of diagnosis, at the same time or after the time of diagnosis. It was important to evaluate the function of extrapulmonary organs and detect the titer of ANCA on a regular basis. Survival time was related to age, BVAS, alveolar hemorrhage and pulmonary infection.