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Characteristics Associated With Delirium Persistence Among Newly Admitted Post-Acute Facility Patients

¹ Research and Training Institute
² Department of Medicine, Hebrew Rehabilitation Center for Aged, Boston, Massachusetts.
³ Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
⁴ Division of General Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
⁵ Division on Aging, Harvard Medical School, Boston, Massachusetts.

Address correspondence to Dan K. Kiely, MPH, MA, Hebrew Rehabilitation Center for Aged, Research and Training Institute, 1200 Centre Street, Boston, MA 02131. E-mail: kiely{at}mail.hrca.harvard.edu

Background. Delirium is costly, common, and may persist for weeks or months. Therefore, the adverse impact of delirium on loss of independence may occur in the post-acute setting rather than in the hospital. The purpose of this study is to describe the rate of delirium persistence and identify baseline patient characteristics that are associated with delirium persistence at 1 month among newly admitted post-acute facility patients who were admitted with delirium.

Methods. Patients were recruited from 4 Boston area skilled nursing facilities specializing in post-acute care (PAC). Assessment instruments included the Confusion Assessment Method Diagnostic Algorithm, the modified Delirium Symptom Interview, the Memorial Delirium Assessment Scale (MDAS), and the Blessed Dementia Rating Scale (BDRS). Multiple logistic regression analyses were used to identify patient characteristics associated with delirium persistence (at 1 month).

Results. Nearly 51% of the 85 delirious patients enrolled in this study had delirium at their 1-month follow-up assessment. Four patient factors associated with delirium persistence were identified: older age (85 years), severe delirium at PAC admission (MDAS score >15), prehospital cognitive impairment based on proxy report [BDRS], and the presence of all 8 modified Delirium Symptom Interview symptoms at PAC admission. Our model has very good predictive power (area under the receiver operating characteristic = 0.85).

Conclusions. Delirium is persistent in the post-acute setting. If verified in further research, the risk factors found in this study could be used to identify patients who are likely to have delirium after 1 month, and may prove useful in developing and targeting interventions of care.