POS1176 HOSPITALIZATION RATES, FEATURES, AND DISCHARGE DIAGNOSES OF A LARGE NATIONWIDE COHORT OF ANCA-ASSOCIATED VASCULITIS

Background Hospitalizations due to relapse or disease complications are major concerns during follow-up of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Objectives To determine rates of hospitalization in a large cohort of patients with AAV compared with the national general population, and to describe features and associated primary discharge diagnoses. Methods Between 2007 and 2018, we examined the hospitalization records of AAV patients from 13 Italian hospitals. Hospitalization dates, features, length of stay, primary discharge diagnoses and patient data were abstracted from charts. Age- and sex-standardized hospitalization rates (SHR) were calculated by an indirect method, per year and for the study period, using the 2007–2018 hospitalization data provided by the Italian Ministry of Health. Multivariable and survival models were used to explore associations between these outcomes, clinical parameters at diagnosis, and pre-existing comorbidities. Results A total of 610 hospitalizations occurred in 635 patients with AAV (19.4% microscopic polyangiitis, MPA; 34.6% granulomatosis with polyangiitis, GPA; 46.0% eosinophilic GPA, EGPA) during a 12-year observation; in 19.8% for life-threatening conditions and leading to death in 2.3%. The median time to first hospitalization was 504 days (25-75%IQR, 95-1497), and the median hospitalization length was 8 days (25-75%IQR, 8-14).The 2018 SHR (95%CI) was 1.14 (0.91, 1.43) for all AAV combined, 1.13 (0.68, 1.76) for MPA, 1.48 (1.02, 2.08) for GPA, and 0.90 (0.60, 1.31) for EGPA. These rates tended to a gradual increase from 2007 to 2018 in the whole AAV cohort of patients and in every disease subset (Figure 1A). The main causes of hospitalization in patients with AAV were infectious diseases (18.7%), followed by major relapse and diagnostic re-evaluation (17.2% each), and cardiovascular diseases (10.8%). Among those due to infections, the main site was the respiratory system (44.6%), followed by urinary tract (9.6%) and sepsis (6.3%). Among AAV patients hospitalized during follow-up (47.1%), 55.5% had only 1 hospitalization, 18.7% had 2, and 25.6% had 3 or more hospitalizations. Patients with a diagnosis of GPA or MPA (versus EGPA), higher vasculitis activity (assessed by BVAS), ANCA positivity at diagnosis, and hospitalization at diagnosis (all p<0.001), more pre-existing comorbidities and older age (both p<0.05), were more likely to be hospitalized during follow-up (Figure 1B). Conclusion Patients with AAV have a significant burden of hospitalization during the disease course. Approximately half of the patients is hospitalized during follow-up, with infections, relapses and cardiovascular diseases as the main causes of hospitalizations. Our findings showed the existence of risk profiles of patients more likely to be hospitalized, requiring more active vigilance.