Clinical characteristics and prognosis for delirium in Spanish internal medicine departments: An analysis from a large clinical-administrative database.

Objectives: To investigate the prevalence of reported delirium and its associated factors and costs.

Design: Retrospective and descriptive analysis of a national clinical-administrative database that includes all patients hospitalised in Spain in internal medicine departments from January 2007 to December 2014.

Material And Method: The study included the patients' sociodemographic and clinical data (sex, age, diagnosis and procedures).

Results: The prevalence of reported delirium was 2.5% (114,343 of 4,628,397 discharge reports). Delirium was most common in the 81-90-year age group (48%) and in institutionalised patients (4.5% vs. 2.9%; P<.001). The diagnoses most associated with delirium were dementia (14% vs. 7% for patients without delirium), cerebrovascular disease (17% vs. 11%), malnutrition (4% vs. 2%), pressure ulcers (4% vs. 2%), dysphagia (2% vs. 0.2%) and hyponatraemia (5% vs. 2%) (P<.001 in all cases). Patients with delirium also had longer mean stays (11.85±13.15days vs. 9.49±11.17) and higher hospital mortality (OR: 1.41; 95%CI: 1.39-1.43; P=.0001). The costs attributable to delirium in 8years exceeded €100 million (almost €1,000 per hospitalisation/patient). We developed a predictive model for the risk of developing delirium, which has insufficient sensitivity but is useful for identifying low-risk patients.

Conclusions: Patients who develop delirium during their hospitalisation in internal medicine have a longer stay, greater mortality and an increased risk of being institutionalised at discharge. Delirium is probably poorly reported in the discharge reports prepared by internists.