Inappropriate psychiatric admission of elderly patients with unrecognized delirium.

Objectives: To explore factors that might contribute to misattribution of mental status changes to psychiatric illness when an elderly patient actually has a delirium (mental status changes due to a medical condition).
Methods: Records of 900 elderly patients referred to a Veterans Affairs psychiatric inpatient unit and 413 to an inpatient psychiatric team at a public hospital from 2001 to 2007 were reviewed. Cases referred because of symptoms secondary to an unrecognized delirium underwent further analysis of preadmission assessments. Comparisons were made to elderly patients with delirium appropriately admitted to medical units.
Results: Thirty (2.3%) of the patients referred to psychiatric units were found to have a physical disorder requiring medical intervention within twelve hours. Compared to 30 delirious patients admitted to medical units, those inappropriately referred to psychiatric units had significantly lower rates of adequate medical histories, physical examinations, cognitive assessments, and laboratory/radiological studies. Among patients with delirium referred to psychiatric units, 66.7% had a history of mental illness, versus 26.7% of comparable admissions to medical units (chi (7) = 60.00, P < 0.001).
Conclusions: Our findings suggest that elderly patients with delirium admitted to psychiatric units are less likely to undergo complete diagnostic assessments than delirious elderly patients admitted to medical units. Symptoms of delirium appear more likely to be incorrectly attributed to psychiatric illness in patients with a history of mental illness than in patients without such a history. Possible explanations for these findings and suggestions for addressing these issues are offered.