Recent temporal trends, characteristics and outcomes of patients with non-COVID-19 community-acquired pneumonia at two tertiary hospitals in Australia: an observational study

Abstract

Background: Community-acquired pneumonia (CAP) leads to considerable morbidity and mortality globally. However, data on CAP burden in Australia, especially during the coronavirus disease 2019 (COVID-19) pandemic, are limited. Aims: We characterised and assessed clinical outcomes of non-COVID-19 CAP hospitalisations over a 6-year period at two major hospitals in South Australia. Methods: All non-COVID-19 CAP hospitalisations were identified using the International Statistical Classification of Diseases and Related Health Problems, Tenth revision, Australian modification (ICD-10-AM) codes, between 1 January 2018 and 31 December 2023, at two tertiary hospitals in Adelaide. Clinical outcomes included in-hospital and 30-day mortality, length of stay (LOS) in, intensive care unit (ICU) admission and 30-day readmissions. Multilevel regression models were utilised to identify predictors of clinical outcomes. Results: Over the 6-year period, there were 7853 non-COVID-19 CAP hospitalisations, with a temporal increase from 100 per 100 000 population in 2018 to 208 per 100 000 population in 2023 (P < 0.001). The mean (SD) age was 75.1 (17.6) years, and 54.6% were males. The mean age declined over time (P < 0.05), while other characteristics remained stable. Streptococcus pneumoniae was the most commonly identified bacterium (21.8% of cases). In-hospital mortality occurred in 7.8% of patients, with 30-day mortality and readmission rates of 14.3% and 16.9% respectively. LOS declined significantly during the pandemic years; however, mortality remained stable over time. Frailty status, malnutrition and number of comorbidities significantly predicted 30-day mortality and LOS, in addition to pneumonia severity and ICU admission. Conclusions: There has been an increasing trend of hospitalisations for non-COVID-19 CAP during the COVID-19 pandemic, with a concomitant trend towards shorter LOS and no significant shift in other clinical outcomes.