Does This Patient Have Delirium?: Value of Bedside Instruments

Abstract

CONTEXT: Delirium occurs in many hospitalized older patients and has serious consequences including increased risk for death and admission to long-term care. Despite its importance, health care clinicians often fail to recognize delirium. Simple bedside instruments may lead to improved identification. OBJECTIVE: To systematically review the evidence on the accuracy of bedside instruments in diagnosing the presence of delirium in adults. DATA SOURCES: Search of MEDLINE (from 1950 to May 2010), EMBASE (from 1980 to May 2010), and references of retrieved articles to identify studies of delirium among inpatients. STUDY SELECTION: Prospective studies of diagnostic accuracy that compared at least 1 delirium bedside instrument to the Diagnostic and Statistical Manual of Mental Disorders-based diagnosis made by a geriatrician, psychiatrist, or neurologist. DATA SYNTHESIS: There were 6570 unique citations identified with 25 prospectively conducted studies (N = 3027 patients) meeting inclusion criteria and describing use of 11 instruments. Positive results that suggested delirium with likelihood ratios (LRs) greater than 5.0 were present for the Global Attentiveness Rating (GAR), Memorial Delirium Assessment Scale (MDAS), Confusion Assessment Method (CAM), Delirium Rating Scale Revised-98 (DRS-R-98), Clinical Assessment of Confusion (CAC), and Delirium Observation Screening Scale (DOSS). Normal results that decreased the likelihood of delirium with LRs less than 0.2 were calculated for the GAR, MDAS, CAM, DRS-R-98, Delirium Rating Scale (DRS), DOSS, Nursing Delirium Screening Scale (Nu-DESC), and Mini-Mental State Examination (MMSE). The Digit Span test and Vigilance "A" test in isolation have limited utility in diagnosing delirium. Considering the instrument's ease of use, test performance, and clinical importance of the heterogeneity in the confidence intervals (CIs) of the LRs, the CAM has the best available supportive data as a bedside delirium instrument (summary-positive LR, 9.6; 95% CI, 5.8-16.0; summary-negative LR, 0.16; 95% CI, 0.09-0.29). Of all scales, the MMSE (score <24) was the least useful for identifying a patient with delirium (LR, 1.6; 95% CI, 1.2-2.0). CONCLUSION: The choice of instrument may be dictated by the amount of time available and the discipline of the examiner; however, the best evidence supports use of the CAM, which takes 5 minutes to administer.