Twenty-eight days later: emergency diagnoses associated with increased risk of readmission, a retrospective observational study of older adults

Aims: To describe diagnostic categories and comorbidities associated with increased risk of readmission within 28 days among older adults. Methods: Retrospective observational study of all hospital admissions following ED attendance by patients aged ≥ 60 years between July 2020 and June 2023. Index and subsequent 28-day readmission were identified using ED data and hospital discharge records. ED diagnosis, Australian Refined Diagnosis-Related Group (AR-DRG) discharge codes, and ICD-10-AM comorbidities were extracted. Multivariate logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations with 28-day readmission. The study and findings have been reported against the STROBE-RECORD guideline. Results: Of the 28,730 initial patient visits, 7.9% re-presented within 28 days. The most common ED diagnoses at initial and readmission were chest pain (5.4% vs. 4.6%), falls (5.2% vs. 4.1%), dyspnoea (3.5% vs. 3.1%), abdominal pain (3.1% vs. 3.3%) and cerebrovascular accident (1.7% vs. 1.7%). The most frequent AR-DRGs were respiratory infections/inflammations, kidney and urinary signs/symptoms, and other digestive system disorders. Key ICD-10-AM codes associated with a higher likelihood of readmission within 28 days were obstructive/reflux uropathy (OR 2.66, 95% CI 1.78–3.96), urinary retention (OR 1.84, 95% CI 1.38–2.46), chronic ischaemic heart disease (OR 1.57, 95% CI 1.10–2.25), delirium (OR 1.35, 95% CI 1.07–1.71) and disorders of fluid, electrolyte, and acid–base balance (OR 1.29, 95% CI 1.09–1.54). Conclusion: Nearly 8% of older adults are readmitted within 28 days. Our described approach offers a potential framework to identify at-risk groups and intervene to reduce avoidable representations and/or admissions.