Objectives: To validate the Memorial Delirium Assessment Scale (MDAS) as a measure of delirium severity in a cohort of patients aged 65 and older; to examine the association between severity of delirium and patient outcomes; and to examine the association between psychomotor variants of delirium and each of those outcomes.
Design: Prospective assessment of sample.
Participants: One hundred twenty-two older patients (mean age +/- standard deviation = 79 +/- 8) who had undergone acute hip fracture surgery.
Measurements: We used standardized instruments to assess prefracture activities of daily living (ADLs), ambulatory status, cognition, and living situation. Postoperatively, each patient was interviewed daily. Delirium was diagnosed using the Confusion Assessment Method (CAM), and delirium severity was measured using the MDAS. The MDAS was also used to categorize the psychomotor types of delirium into "purely hypoactive" or "any hyperactivity." Telephone or face-to-face interviews were conducted at 1 and 6 months to assess survival, ADL function, ambulatory status, and living situation.
Results: Of 122 patients, 40% developed CAM-defined delirium. Delirious patients had higher average MDAS scores than nondelirious patients (11.7 vs 2.4, P <.0001). We used the median of the average MDAS score to classify patients into mild or severe delirium. Severe delirium was generally associated with worse outcomes than was mild delirium, and the associations reached statistical significance for nursing home placement or death at 6 months (52% vs 17%, P =.009). Additionally, patients who did not meet full CAM criteria for delirium experienced worse outcomes if they had some symptoms of delirium than if they had no or few symptoms (nursing home placement or death at 6 months: 27% vs 0%, P =.001). Surprisingly, these patients with subsyndromal delirium who did not fulfill CAM criteria for delirium but demonstrated significant delirium symptoms, had outcomes similar to or worse than those with mild CAM-defined delirium. Pure hypoactive delirium accounted for 71% (34/48) of cases and was less severe than was delirium with any hyperactivity (average MDAS score 10.6 vs 14.8, P =.007). In our cohort, patients with pure hypoactive delirium had better outcomes than did those with any hyperactivity (nursing home placement or death at 1 month: 32% vs 79%, P =.003); this difference persisted after adjusting for severity.
Conclusion: In this study of delirium in older hip fracture patients, the MDAS, a continuous severity measure, was a useful adjunct to the CAM, a dichotomous diagnostic measure. In patients with CAM-defined delirium, severe delirium was generally associated with worse outcomes than was mild delirium. In patients who did not fulfill CAM criteria, subsyndromal delirium was associated with worse outcomes than having few or no symptoms of delirium. Patients with subsyndromal delirium had outcomes similar to patients with mild delirium, suggesting that a dichotomous approach to diagnosis and management may be inappropriate. Pure hypoactive delirium was more common than delirium with any hyperactive features, tended to be milder, and was associated with better outcomes even after adjusting for severity. Future studies should confirm our preliminary associations and examine whether treatment to reduce the severity of delirium symptoms can improve outcomes after hip fracture repair.