The Clinical Features And Prognosis Of ANCA Associated Interstitial Pneumonia

Objective ANCA-associated vasculitis(AAV)is a group of autoimmune diseases that involve small blood vessels and cause multiple system damage,among which kidney and lung damage are the most common target organs.AAV lung damage often contains interstitial pneumonia(IP)due to repeated alveolar hemorrhage.However,IP in some patients precedes AAV.In addition,we often observe that IP patients only have ANCA positive cases but do not meet the diagnostic criteria of AAV,and there is no clear definition of the relationship among ANCA,AAV and IP.Therefore,the purpose of this study is to understand the clinical characteristics and prognosis of such specific ANCA positive IP patients who were not diagnosed with AAV(defined as ANCA associated interstitial pneumonia),as well as to further understand the incidence of IP in AAV patients and its effect on prognosis.Methods 36 cases which diagnosed IP but not conform to ANCA associated vasculitis(ANCA-IP patients),19 cases which both diagnosed with IP and ANCA associated vasculitis(AAV-IP patients),27 AAV patients without pulmonary involvement in vasculitis were classified as AAV-N group,and 40 patients of idiopathic interstitial pneumonia(IIP)were studied by a retrospective method.The differences of clinical features,laboratory indexes,pulmonary High Resolution CT(HRCT)images,the treatment and its prognosis were compared among groups.Kruskal-Wallis H test,chi square method,multivariate Logistic regression and Kaplan-meier method were used for statistical analysis.Results(1)There were no significant differences in age and sex among ANCA-IP,AAV-IP,and IIP groups.Dyspnea was the most common clinical manifestation in IIP group;the white blood count(WBC),creatinine(Cr),C-reactive protein(CRP),erythrocyte sedimentation rate(ESR)were all significantly higher in AAV-IP group.Honeycomb sign within the lessions of pulmonary HRCT was found more frequently in ANCA-IP group than others.(2)In terms of the prognosis,the patients with low doses of glucocorticoid or symptomatic treatment had better prognosis than large doses of glucocorticoid combined with CTX.In contrast,no differences were exhibited with three different treatments in IIP group.(3)What was significant was that during the follow-up period,2.8%(1 case)of ANCA-IP patients progressed to AAV after 25 months.(4)Multivariate Logistic regression analysis showed that large doses of glucocorticoid combined with CTX treatment was a related risk factor for survival.(5)No statistically significant difference about age or gender were detected between AAV-IP and AAV-N groups,dyspnea and cough were more common in the AAV-IP group.Urine routine,white blood cell,creatinine,C reactive protein and erythrocyte sedimentation rate in AAV-IP group were similar to AAV-N group.(6)Our results showed reticular,honeycomb lung and ground-glass shadow were found on HRCT in AAV-IP patients.In the AAV-N group,bronchiectasis,nodules and pleural effusion might be existed on HRCT.(7)Moreover,the mortality rate of AAV-IP patients was significantly higher than that of AAV-N group.Conclusion In our study,we concluded that the ANCA-IP patients probably be in a stable condition for a long time and keep long-term not progressing to AAV,because it may be an early stage of AAV or an independent state of the disease,aggressive immunosuppressive therapy may not be applied in ANCA-IP.IP is common in AAV patients and it even can occur before AAV.What’s more,AAV patients with IP often have worse prognosis.