Delirium

C The Author 2008. Published by Oxford University Press on behalf of the British Geriatrics Society. Age and Ageing 2009; 38: 19–26 doi: 10.1093/ageing/afn253 All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org Published electronically 18 November 2008

SYSTEMATIC REVIEW

Persistent delirium in older hospital patients: a systematic review of frequencyand prognosis
MARTIN G. COLE1,2 , ANTONIO CIAMPI3,4 , ERIC BELZILE3 , LIHONG ZHONG3
Department of Psychiatry, St. Mary’s Hospital Center, Montreal, Quebec, Canada Department of Psychiatry, McGill University, Montreal, Quebec, Canada 3 Department of Clinical Epidemiology and Community Studies, St. Mary’s Hospital Center, Montreal, Quebec, Canada 4 Department of Epidemiology and Biostatistics,McGill University, Montreal, Quebec, Canada
2 1

Address correspondence to: Martin G. Cole. Tel: (+1) 5143453511, Ext. 5060; Fax: (+1) 5147342652. Email: martin.cole@ssss.gouv.qc.ca

Abstract
Background: one explanation for the poor prognosis of delirium among older hospital patients may be that many of these patients do not recover from delirium. We sought to determine the frequency andprognosis of persistent delirium (PerD) in older hospital patients by systematically reviewing original research on this topic. Methods: MEDLINE, EMBASE, PsycINFO and the Cochrane Database of Systematic Reviews were searched for potentially relevant articles. The bibliographies of relevant articles were searched for additional references. Eighteen reports (involving 1,322 patients with delirium) metthe following seven inclusion criteria: original research published in English or French, prospective study design, study population of at least 20 hospital patients, patients aged 50 years or more, follow-up of at least 1 week, acceptable definition of delirium at enrolment and included at least one assessment for PerD at discharge or later. The methods of each study were assessed according tothe six criteria for prognostic studies described by the Evidence-Based Medicine Working Group. Information about the sample origin and size, age, proportion with dementia, criteria for delirium, timing of follow-up assessments, criteria for PerD, proportion with PerD and prognosis of PerD was systematically abstracted from each report, tabulated and combined using standard meta-analysistechniques. Results: the combined proportions with PerD at discharge, 1, 3 and 6 months were 44.7% (95% CI 26.8%, 63.7%), 32.8% (95% CI 18.4%, 47.2%), 25.6% (95% CI 7.9%, 43.4%) and 21% (95% CI 1.4%, 40.6%), respectively. The outcomes (mortality, nursing home placement, function, cognition) of patients with PerD were consistently worse than the outcomes of patients who had recovered from delirium.Conclusion: PerD in older hospital patients is frequent, appears to be associated with adverse outcomes and may account for the poor prognosis of delirium in this population. These findings have potentially important implications for clinical practice and research.
Keywords: persistent delirium, aged, frequency, prognosis, elderly

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Introduction
Delirium is a cognitive disorder defined by acute onset, fluctuating course and disturbances of consciousness, attention, orientation, memory, thought, perception and behaviour [1]. It occurs in hyperactive, hypoactive or mixed forms in up to 50% of older hospital patients [2,3], many with pre-existing dementia [4]. Traditionally, the course of delirium has beendescribed as transient [5], in which recovery is likely to be com-

plete if the underlying etiological factor is promptly corrected or self-limited [1]. Among older hospital patients, however, the prognosis is poor [3,6]. In this population, delirium is associated with significant increases in cognitive impairment and functional disability [7–9], length of hospital stay [10,11], rates of...