Prevalence and risk factors of delirium in psychogeriatric outpatients

BACKGROUND: Delirium is a serious neuropsychiatric syndrome, which requires timely treatment. However, it is easily missed, especially in older patients with premorbid cognitive disorders. OBJECTIVES: The aim of this study is to investigate the prevalence and risk factors of delirium in older outpatients with and without dementia. METHOD: We assessed 444 patients referred to the memory clinic of a psychiatric hospital between March 2013 and March 2014. Demographic information, medical history, impairments in daily living activities and referral information were registered. Patients underwent a psychiatric examination using the Delirium Rating Scale‐Revised‐98 and cognitive tests, a physical examination and laboratory tests. We recorded medication use and changes before and after the onset of symptoms. RESULTS: Among the 444 outpatients, 85 had probable delirium (prevalence of 19%), and 10 had subsyndromal delirium (2%). The most common triggers were infection (42%), drug‐intoxication or withdrawal (22%), and metabolic/endocrine disturbance (12%). Age (OR 1.07, 95% CI 1.02‐1.11) and prior delirium (OR 3.34, 95% CI 1.28‐8.69) were independent non‐modifiable factors associated with an increased risk of delirium. The only independent modifiable risk factor was infection (OR 17.31, 95% CI 8.44‐35.49). CONCLUSIONS: A delirium was detected in one of five patients referred for dementia screening. Most patients could be treated at home. Age and prior delirium were predictive of an increased risk of delirium.