Risk of opportunistic infections in patients with antineutrophil cytoplasmic antibody‐associated vasculitis, using a Japanese health insurance database

Abstract Aim Opportunistic infections (OIs) adversely affect outcomes in patients with antineutrophil cytoplasmic antibody‐associated vasculitis (AAV). This study aimed to identify the incidence proportion of risk factors for OIs in patients with AAV who were on remission‐induction therapy, using a Japanese health insurance database. Method This retrospective longitudinal population‐based study was conducted using claims data provided by Medical Data Vision Co., Ltd. We defined individuals as AAV cases receiving remission‐induction therapy if they met all of the following criteria: (a) having OIs with at least 1 specified International Statistical Classification of Diseases and Related Health Problems, 10th Revision code (M300, M301, M313, or M318); (b) receiving at least 1 prescription of oral corticosteroids (CS) with prednisolone (PSL)‐equivalent dosage ≥30 mg/d, CS pulse therapy, immunosuppressive agents or rituximab during hospitalization between April 2008 and April 2017; and (c) at least 7 days of hospitalization while on the above‐mentioned therapies. We calculated incidence and proportion of OIs during the year following remission‐induction therapy and the adjusted odds ratio (OR) using a logistic regression model. Results We included 2299 patients with AAV in this study. OIs occurred in 460 patients (20.0%), with the most frequently occurring OI being cytomegalovirus infection (n = 122, 6.5%). After adjusting for covariates, age by decade (OR 1.24, 95% CI: 1.12‐1.36), daily PSL dose per 10 mg (OR 1.16, 95% CI: 1.08‐1.25), and CS pulse therapy (OR 1.29, 95% CI: 1.04‐1.60) were found to be significantly associated with occurrence of OIs. Conclusion Older age and corticosteroid use were found to be significant risk factors for OIs in patients with AAV on remission‐induction therapy, using a health insurance database.