Delirium, a common cause for acute hospitalization among elderly patients is associated with significant morbidity, mortality, and economic cost especially with re-hospitalizations.  Studying risk factors associated with unplanned readmission may help lower readmission rates.

To study nationwide statistics of 30-day readmissions (30-DR) among elderly patients following hospitalization for delirium.

This was a retrospective observational study of elderly patients (age ≥65 years) hospitalized with a primary discharge diagnosis of delirium using the 2013 Nationwide Readmission Database (NRD).  Cases were identified by ICD9-CM codes linked to drug-induced delirium, alcohol-withdrawal delirium, encephalopathy-NOS, subacute delirium, and delirium with dementia.  The causes of 30-DR were identified by primary readmission discharge diagnoses. Multivariate logistic regression analyses were performed adjusting for stratified cluster design of NRD to identify the patient/system-specific factors associated with 30-DR.

Overall 30-DR rate was 17% (7140 of 42,655 weighted index admissions) and the median interval to readmission was 10 days.  The common causes of readmission were infection (18%), systemic diseases (11.4 %; acute kidney injury, congestive heart failure, respiratory failure), CNS disorders (5.9%), delirium-associated cognitive disorders (4.8%), alcohol-related (2.5%), and aspiration pneumonia (2.2%).  Compared to initial (index) hospitalization, readmission had higher mean length-of-stay (LOS; 6.9 vs. 6.1 days, p<0.0001) and hospitalization cost ($12594 vs. $10533, p<0.0001).  Independent predictors of readmission included discharge against medical advice (OR 1.9, p< 0.0034), >6 days LOS (OR 1.3, p<0.0001), chronic renal failure (OR 1.4, p<0.0001), CHF (OR 1.3, p<0.0001), chronic lung disease (OR 1.2, p<0.0004), and chronic liver disease (OR 1.2, p<0.03).  Having private insurance was associated with a lower risk of readmission (OR 0.78, p<0.02).

The 30-DR rate among elderly patients hospitalized with delirium was 17%.  The main predictors of readmission were sepsis and systemic diseases.  Implementation of care pathways to optimize management of these conditions may help reduce avoidable readmissions and associated cost.