Predictors of Delirium Development in Older Medical Inpatients: Readily Identifiable Factors at Admission

Article type: Research Article

Authors: O’Regan, Niamh A.^{a; b; c; *} | Fitzgerald, James^d | Adamis, Dimitrios^e | Molloy, David William^a | Meagher, David^{d; f} | Timmons, Suzanne^a

Affiliations: [a] Centre for Gerontology and Rehabilitation, School of Medicine, University College Cork, Cork, Ireland | [b] Department of Medicine, Division of Geriatric Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada | [c] St. Joseph’s Healthcare London – Parkwood Institute, London, Ontario, Canada | [d] Graduate Entry Medical School, University of Limerick, Limerick, Ireland | [e] Sligo Mental Health Services, Sligo, Ireland | [f] Cognitive Impairment Research Group, Centre for Interventions in Infection, Inflammation & Immunity (4i), Graduate Entry Medical School, University of Limerick, Ireland

Correspondence: [*] Correspondence to: Niamh A. O’Regan, MB BCh BAO, BMedSci, MRCPI, PhD, Assistant Professor, Department of Medicine, Division of Geriatric Medicine, St. Joseph’s Healthcare London – Parkwood Institute, 550 Wellington Rd., London, Ontario, N6C 0A7, Canada. Tel.: +1 519 685 4021; E-mail: [email protected]

Abstract: Background:Identifying patients at high risk of delirium is crucial to facilitate prevention. Although dementia is the most consistent risk factor across populations, it remains under-diagnosed. Hence understanding other markers of delirium vulnerability on admission is important. Objective: We aimed to identify predictors of incident delirium development in older medical inpatients that were readily identifiable at presentation to the emergency department. Methods:Medical inpatients of ≥70 years were assessed on admission for delirium using the Revised Delirium Rating Scale (DRS-R98) and those with prevalent delirium were excluded. Consenting non-delirious patients were then assessed daily using the DRS-R98. Data pertaining to multiple baseline delirium risk factors were collected, including pre-morbid dementia. Multivariable logistic regression was used to examine which factors predicted the development of incident delirium. Results:Of 555 patients approached, 184 (33.1%) had prevalent delirium. Following other exclusions, 191 were included in the study and 61 developed incident delirium. Predictors of incident delirium on multivariable analysis, controlling for confounders, were dementia (OR 2.54, 95% CI 1.01–6.43, p = 0.048); Barthel Index score (OR 1.15 for each unit decrease in score, 95% CI 1.06–1.25, p = 0.001), and Modified Cumulative Illness Rating Scale score (OR 1.13 for each unit increase in score, 95% CI 1.05–1.22, p = 0.001). Conclusion:Dementia is a well-known risk factor for delirium; however, it too is under-recognized and on admission can be missed. Conversely, the Barthel Index is a simple and widely used measure of functional ability that may prove useful in stratifying those at risk of in-hospital delirium on admission.

Keywords: Comorbidity, delirium, dementia, frail elderly, risk factor

DOI: 10.3233/JAD-180178

Journal: Journal of Alzheimer's Disease, vol. 64, no. 3, pp. 775-785, 2018