The American Psychiatric Association Practice Guideline for the Prevention and Treatment of Delirium, Second EditionThe American Psychiatric Association Practice Guideline for the Prevention and Treatment of Delirium, Second Edition Prevalence rates of delirium range widely depending on patient population and treatment setting. Information on rates of delirium in community settings is limited, but in emergency and hospital settings, one quarter or more of the patients will experience delirium. Rates can be even higher in older individuals, critical care patients,