Hospital outcomes in interstitial lung disease-related admissions: a multicentre retrospective study in the North West of England.

BackgroundInterstitial lung diseases (ILD) are a heterogenous group of often progressive, unpredictable diseases. They frequently result in hospitalisations secondary to respiratory decompensation, termed ILD-related admissions. A proportion of these are due to acute exacerbations (AEILD). All are associated with high mortality but poorly characterised in real-world populations. AimTo evaluate mortality outcomes and associated risk factors following ILD-related hospital admissions, including AEILD. MethodsWe conducted a multicentre retrospective cohort study of primary ICD10 coded admissions for ILD between 01.01.2017 and 31.12.2019 across 11 NHS hospitals in the North West of England. AEILD events were classified using clinical criteria: a <30-day respiratory deterioration not secondary to cardiac failure, pulmonary embolism or pneumothorax. The AEILD sub-group was subsequently divided into those with CT confirmation (definite AEILD) and without CT confirmation (suspected AEILD). Primary outcome was time from admission to death. Statistical analyses included Kaplan-Meier survival and multivariate cox proportional hazards modelling. ResultsOf 938 admissions ILD-related admissions, 54.5% met study AEILD criteria. Overall, 90-day all-cause mortality was 40.2%. Median survival of the AEILD cohort was 107 days (95% CI 87.0 - 141.0 days) and other ILD-related admission cohort 241.0 days (95% CI 208.0 - 308.0 days), with a statistically significant difference in survival (p <0.0001). 37.6% (192/511) of AEILD events had CT confirmation. Within the AEILD sub-group, median survival was higher in the CT group (144 days vs. 100 days, p = 0.027). AEILD was independently associated with mortality in a multivariate model, and pre-admission oxygen, age and neutrophilia were associated with mortality in both ILD-admission and AEILD 90-day all-cause mortality models. Only 13.9% of admissions had documented palliative care input. ConclusionMortality associated with ILD-related admissions is high, with AEILD events independently associated with high mortality. Findings highlight the need for improved education, improved access to palliative care and targeted AEILD research. Key MessagesO_ST_ABSWhat is already known on this topic.C_ST_ABSHospital admissions in interstitial lung disease (ILD) carry a high risk of mortality, particularly when precipitated by an acute exacerbation (AEILD). Prior international surveys have highlighted clinician heterogeneity in the approach to AEILD, but there is very limited real-world data describing admission outcomes, diagnostic and treatment patterns from the UK. What this study adds.This study adds to the understanding that AEILD conveys poor survival outcomes and highlights age, pre-admission oxygen use and neutrophilia as poor prognostic indicators. It highlights underuse of CT for diagnostic confirmation and demonstrates that a lack of CT confirmation is associated with shorter survival in simple modelling. It also demonstrates low palliative care inpatient service utilisation. How this study might affect research, practice or policy.These findings highlight the urgent need for consistent diagnostic pathways, equitable access to CT imaging and early multidisciplinary input for AEILD. Improved education of the non-specialist, patients and their relatives could improve recognition and outcomes in this high-risk population - including timeline access to palliative care and acute admission burden.