Medical illnesses and risk of delirium in acute hospitalized adult-older patients

Objectives: The pathogenesis of delirium in hospitalised patients is complex and multi-factorial. Although several medical conditions had been associated with delirium, the real impact of different diseases on delirium onset has not been completely clarified. In this study we provided a comparison of delirium prevalence across various diseases in a large sample of adult/older individuals > 60 years (mean age: 70.5 years) admitted to acute medical wards. Design: Observational cross-sectional study. Setting: St. Anna University Hospital (Ferrara, Italy). Population: Hospital-based population; data from 74.379 consecutive discharge records of subjects ≥ 60 years were analysed. Measurements: DRGs, primary/secondary diagnosis (ICD-9-CM code), number of procedures and admissions, length of hospital stay, and possible death were evaluated. ICD-9 codes for delirium included 290.11, 290.3, 290.41, 293.0, and 293.1. Results: Overall, 1300 patients received a delirium diagnosis. Compared with controls, they were characterized by higher number of diagnoses, procedures, and comorbidity. The risk of delirium was associated with DRGs related to brain pathologies, major orthopaedic diseases/procedures, and major infections. As regards ICD-9 diagnoses, 13.7% (n.179) of delirium diagnoses could be attributable to cerebral atherosclerosis, 9.3% (n.121) to urinary tract infections, 6.5% (n.85) to Alzheimer’s disease, 5.5% to hypertension, 3.6% to diabetes, and 3.5% to atrial fibrillation (total: 42.1%). Conclusions: Our data suggest that among hospitalised elderly patients urinary infections might represent the most frequent modifiable risk factor for delirium. Clinicians need to have a high index of suspicion as regards the presence of urinary tract infections in this subjects, especially in those with cognitive impairment, since its early recognition and treatment might contribute to decrease the probability of delirium onset.