B41-38 Respiratory-Related Hospitalizations in Autoimmune-Spectrum Interstitial Lung Disease: A 10-Year Retrospective Cohort From a Large Academic Health System

Abstract Rationale Respiratory-related hospitalizations (RRH) are associated with significant morbidity and mortality among patients with interstitial lung disease (ILD). Common causes of acute presentations include infection, acute exacerbations, and/or disease progression. This study describes the characteristics, hospital courses, treatment regimens, and outcomes of patients hospitalized receiving steroid treatment for an acute presentation of connective tissue-associated ILD (CTD-ILD), idiopathic pneumonia with autoimmune features (IPAF), or idiopathic nonspecific interstitial pneumonia (iNSIP). Methods We conducted a retrospective cohort study of patients admitted with worsening ILD to hospitals in the University of North Carolina Health System between 10/2015 and 5/2025. Subjects were screened from the electronic medical record who met ICD-10 criteria for 1) RRH; 2) CTD-ILD, IPAF, or iNSIP; and 3) steroid treatment for ILD. Patients whose symptoms were fully attributable to heart failure or a non-parenchymal respiratory etiology were excluded. We performed a systematic evaluation of clinical variables, diagnostic testing, hospitalization management and vital status. Results We screened 1110 subjects and identified 127 hospitalizations from 107 subjects with an acute presentation of ILD. Subjects were predominately female (59%) and white (45%). The average age at admission was 61 years. The most common ILD subtypes were myositis (24%), rheumatoid arthritis (22%), IPAF (20%) and iNSIP (18%). Baseline characteristics at admission are presented in Table 1. On admission, 41/125 (33%) patients required large bore nasal cannula or greater, and 29/124 (23%) were admitted directly to the ICU. Thirty-four patients (26%) had a culture-positive infection on admission, 28 of which were from a pulmonary source. Antibiotics were initiated within two days of admission in 92/123 (75%) of patients. Twenty-six (20%) subjects underwent bronchoscopy with nine diagnostic BAL results. Thirty-seven subjects (29%) received 500 milligrams or greater prednisone equivalents within seven days of admission. Forty-seven patients (37%) also received a new or increased dose of adjunct/immunosuppression therapy. The percentage of patients who survived transplant-free to discharge was 87%. Thirty-two patients (28%) were re-hospitalized within thirty days, and one patient died within thirty days of discharge. Conclusions In this cohort of patients receiving steroids for an acute presentation of CTD-ILD, IPAF, or NSIP, nearly one-third required high amounts of oxygen support or intensive care at admission. Broad spectrum antibiotics and high dose steroids were both commonly prescribed, reflecting diagnostic uncertainty, though bronchoscopy was infrequent. Patients were frequently re-admitted within thirty days. Given the morbidity of these presentations, prospective studies are warranted to guide optimal diagnostic evaluation and treatment strategies. This abstract is funded by: none