Influence of prior cognitive impairment on the severity of delirium symptoms among older patients.

Delirium is common among hospitalized elderly patients with prior cognitive impairment. Detecting delirium superimposed on dementia is a challenge for nurses and doctors. As a result, delirium among demented elderly patients is of increasing interest to healthcare professionals. So far, studies have failed to describe how symptoms of delirium are altered by severity of dementia. This would be valuable information to improve the rate of detection by nurses of delirium among demented patients. However, until now no research has examined the effect of severity of prior cognitive impairment on the severity of delirium symptoms among institutionalized older patients. This study describes the effect of severity of prior cognitive impairment on the severity of delirium symptoms among institutionalized older patients with delirium at the time of their admission to an acute care hospital. One hundred four institutionalized elderly people were included in this study and screened for delirium using the confusion assessment method. Patients with delirium (n = 71) were evaluated with the delirium index to determine the severity of the symptoms of delirium. The results showed that the severity of prior cognitive impairment influences the severity of most of the symptoms of delirium, particularly disordered attention, orientation, thought organization, and memory. Thus, taking into account the severity of prior cognitive impairment could help nurses to detect delirium among older patients.