Emergency department presentations of community-acquired lower respiratory tract disease in Bristol, UK: a prospective cohort study 2022-2023.

Background: Recent reports highlight the importance of acute lower respiratory tract disease (aLRTD) for patients, but data describing incidence and burden in emergency departments (ED) are lacking.

Methods: A cohort study ascertaining cases prospectively at two EDs in Bristol, UK, enrolling adults (≥18 years) presenting with aLRTD from 1 August 2022 to 31 July 2023. Multivariate logistic regression modelled risk of hospitalisation. Incidence was estimated per 1000 person-years, using adult population estimates for the AvonCAP study catchment area.

Results: 151 865 ED visits, with 9452 (6.2%) aLRTD cases: 2376 (25%) were discharged and 7076 (75%) subsequently hospitalised, including:3663 (38.8%) pneumonia, 4167 (44.1%) non-pneumonic lower respiratory tract infection and 1622 (17.2%) cases without evidence of infection. Univariate analysis demonstrated that aLRTD patients discharged were younger than those hospitalised (median age 43.4 years, IQR 29.4-62.3 vs 74.0 years, IQR 59.8-83.5), and less likely to have pneumonia (17.0% vs 46.0%, respectively). Smoking, heart failure at presentation and underlying chronic cardiac disease conferred risk of admission, above an age effect in the adjusted logistic regression model.Total ED aLRTD incidence was 12.8/1000 person-years (9.6 admitted, 3.2 seen and discharged), with incidences of 7.0 and 36.8/1000 person-years in 18-64 years and ≥65 years, respectively, and incidence increased with patient age: 39.5 and 82.5/1000 person-years in 75-84 years and ≥85 years age groups, respectively.

Interpretation: We report a higher ED aLRTD incidence than in recent British Thoracic Society and Getting It Right First Time reports. This is concerning, particularly in older adults, and may be reduced by respiratory disease optimisation and public health initiatives including smoking cessation and vaccination programmes.