Risk factors for secondary infection in the treatment with anti-neutrophil cytoplasmic antibody-associated vasculitis

Abstract

Objective To investigate the clinical characteristics and risk factors of secondary infection in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). Methods One hundred and eighteen patients newly diagnosed with AAV at the institute of nephrology, Tongji hospital affiliated to Huazhong university of science and technology, from 2012 to 2017, were analyzed retrospectively. Induction therapy included single corticosteroids, combination of corticosteroids with cyclophosphamide and combination of corticosteroids with other immunosuppressive agents. End point was defined as moderate to severe infection which was diagnosed by the clinical and radiological manifestation as well as microbiological evidences. The infection-related survival curve was drawn to reflect the time when the infection occurred. The clinical baseline variables in patients with and without infection were compared. Multivariate Logistic regression model was used to determine the independent predictors of infection. Receiver-operating characteristic curve (ROC) was plotted for evaluating the predictive value of lymphocyte on moderate to severe infection. Results During follow-up of median 3 months (1-30 months), 88 infection episodes were found in 63 (53.4%) patients, of which 54 times (61.4%) occurred within 6 months after treatment, 46 times (52.3%) happened within 3 months after treatment. The most common organ of infection was lung (62.5%), and the most common pathogen was bacteria (51.1%). Multivariate Logistic regression model showed that lung involvement (OR=4.44, 95% CI 1.59-12.41), moderate reduction of lymphocyte in follow-up (OR=5.69, 95% CI 2.05-15.85) and severe lymphocyte reduction (OR=36.28, 95%CI 3.45-381.17) were independent risk factors of secondary infection in AAV patients (all P<0.05). ROC curve showed that the area under the curve of lymphocyte as a predictor of severe infection was 0.767 (95% CI 0.64-0.89, P<0.05). Based on lymphocyte less than 0.49×109/L which was the cut-off value for predicting severe infection, the sensitivity and the specificity were 83.9% and 71.9%, respectively. Conclusions Lung involvement and moderate-severe lymphopenia during follow-up are independent risk factors of secondary infection in AAV patients. Hence, physician should pay more attention to those patients, and adjust treatment in time to avoid the occurrence of infection. Key words: Antibodies, antineutrophil cytoplasmic; Infection; Risk factors; Lymphopenia; Anti-neutrophil cytoplasmic antibody-associated vasculitis