Delirium in elderly general medical inpatients: a prospective study

Background: More than 49% of all US hospital days are spent caring for patients with delirium. There are few Australian data on this important condition. The aim of the study was to determine the prevalence and incidence of delirium in older medical inpatients in a metropolitan teaching hospital, the incidence of known risk factors and current practice in identifying and managing patients at risk of this condition. Methods: Patients aged 65 years or more, and admitted to a general medical unit, were eligible for study inclusion. Participants were screened with an Abbreviated Mental Test Score (AMTS) and chart review. Confusion Assessment Method was used to diagnose delirium if confusion was documented or AMTS < 8. Barthel Index (BI), demographics, delirium risk factors and management were recorded. Results: Prevalent delirium was diagnosed in 19 of 104 (18%) and incident delirium in 2 of 85 (2%) participants. Pre-existing cognitive impairment and admission AMTS < 8 were strongly associated with prevalent delirium (P-values < 0.01). Age > 80 years, Barthel Index <= 50, use of high-risk medications and electrolyte disturbance were also associated with prevalent delirium. Prevalent delirium was not recognized by the treating unit in 4 of 19 cases (21%). Five of 104 (4.8%) of participants had a formal cognitive assessment on admission. One of 19 patients (5.3%) with prevalent delirium had an orientation device in their room. Conclusion: Pre-existing cognitive impairment and admission AMTS are strong predictors of delirium. Despite this, formal cognitive assessment is not routinely carried out in elderly medical patients. Recognition of delirium may be improved by routine cognitive assessment in elderly medical patients.