Predictors of hospital readmission for patients diagnosed with delirium: An electronic health record data analysis.

INTRODUCTION: Delirium is an acute and fluctuating change in attention and cognition that increases the risk of functional decline, institutionalisation and death in hospitalised patients. After delirium, patients have a significantly higher risk of readmission to hospital. Our aim was to investigate factors associated with hospital readmission in people with delirium. METHODS: We carried out an observational retrospective cohort study using linked mental health care and hospitalisation records from South London. Logistic regression models were used to predict the odds of 30-day readmission and Cox proportional hazard models to calculate readmission risks when not restricting follow-up time. RESULTS: Of 2814 patients (mean age 78.9 years SD ±11.8) discharged from hospital after an episode of delirium, 823 (29.3%) were readmitted within 30 days. Depressed mood (odds ratio (OR) 1.34 (95% confidence interval (CI) 1.08-1.66)), moderate-to-severe physical health problems (OR 1.67 (95% CI 1.18-2.2.36)) and a history of serious circulatory disease (OR 1.29 (95% CI 1.07-1.55)) were associated with higher odds of hospital readmission, whereas a diagnosis of delirium superimposed on dementia (OR 0.67 (95% CI 0.53-0.84)) and problematic alcohol/substance (OR 0.54 (95% CI 0.33-0.89)) use were associated with lower odds. Cox proportionate hazard models showed similar results. CONCLUSION: Almost one-third of patients with delirium were readmitted within a short period of time, a more detailed understanding of the underlying risk factors could help prevent readmissions. Our findings indicate that the aetiology (as alcohol-related delirium), the recognition that delirium occurred in the context of dementia, as well as potentially modifiable factors, as depressed mood affect readmission risk, and should be assessed in clinical settings.