Delirium detection in the emergency department: A diagnostic accuracy meta-analysis of history, physical examination, laboratory tests, and screening instruments

INTRODUCTION

Geriatric emergency department (ED) guidelines emphasize timely identification of delirium. This article updates previous diagnostic accuracy systematic reviews of history, physical examination, laboratory testing, and ED screening instruments for the diagnosis of delirium as well as test-treatment thresholds for ED delirium screening.

METHODS

We conducted a systematic review to quantify the diagnostic accuracy of approaches to identify delirium. Studies were included if they described adults aged 60 or older evaluated in the ED setting with an index test for delirium compared with an acceptable criterion standard for delirium. Data were extracted and studies were reviewed for risk of bias. When appropriate, we conducted a meta-analysis and estimated delirium screening thresholds.

RESULTS

Full-text review was performed on 55 studies and 27 were included in the current analysis. No studies were identified exploring the accuracy of findings on history or laboratory analysis. While two studies reported clinicians accurately rule in delirium, clinician gestalt is inadequate to rule out delirium. We report meta-analysis on three studies that quantified the accuracy of the 4 A's Test (4AT) to rule in (pooled positive likelihood ratio [LR+] 7.5, 95% confidence interval [CI] 2.7-20.7) and rule out (pooled negative likelihood ratio [LR-] 0.18, 95% CI 0.09-0.34) delirium. We also conducted meta-analysis of two studies that quantified the accuracy of the Abbreviated Mental Test-4 (AMT-4) and found that the pooled LR+ (4.3, 95% CI 2.4-7.8) was lower than that observed for the 4AT, but the pooled LR- (0.22, 95% CI 0.05-1) was similar. Based on one study the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) is the superior instrument to rule in delirium. The calculated test threshold is 2% and the treatment threshold is 11%.

CONCLUSIONS

The quantitative accuracy of history and physical examination to identify ED delirium is virtually unexplored. The 4AT has the largest quantity of ED-based research. Other screening instruments may more accurately rule in or rule out delirium. If the goal is to rule in delirium then the CAM-ICU or brief CAM or modified CAM for the ED are superior instruments, although the accuracy of these screening tools are based on single-center studies. To rule out delirium, the Delirium Triage Screen is superior based on one single-center study.

Can we improve delirium prevention and treatment in the emergency department? A systematic review

BACKGROUND

This systematic review was conducted to evaluate any interventions to prevent incident delirium, or shorten the duration of prevalent delirium, in older adults presenting to the emergency department (ED).

METHODS

Health sciences librarian designed electronic searches were conducted from database inception through September 2021. Two authors reviewed studies, and included studies that evaluated interventions for the prevention and/or treatment of delirium and excluded non-ED studies. The risk of bias (ROB) was evaluated by the Cochrane ROB tool or the Newcastle-Ottawa (NOS) scale. Meta-analysis was conducted to estimate a pooled effect of multifactorial programs on delirium prevention.

RESULTS

Our search strategy yielded 11,900 studies of which 10 met study inclusion criteria. Two RCTs evaluated pharmacologic interventions for delirium prevention; three non-RCTs employed a multi-factorial delirium prevention program; three non-RCTs evaluated regional anesthesia for hip fractures; and one study evaluated the use of Foley catheter, medication exposure, and risk of delirium. Only four studies demonstrated a significant impact on delirium incidence or duration of delirium-one RCT of melatonin reduced the incidence of delirium (OR 0.19, 95% CI 0.06 to 0.62), one non-RCT study on a multi-factorial program decreased inpatient delirium prevalence (41% to 19%) and the other reduced incident delirium (RR 0.37, 95% CI 0.22 to 0.61). One case-control study on the use of ED Foley catheters in the ED increased the duration of delirium (proportional OR 3.1, 95% CI 1.3 to 7.4). A pooled odds ratio for three multifactorial programs on delirium prevention was 0.46 (95% CI 0.31-0.68, I2  = 0).

CONCLUSION

Few interventions initiated in the ED were found to consistently reduce the incidence or duration of delirium. Delirium prevention and treatment trials in the ED are still rare and should be prioritized for future research.

Risk Factors for Delirium in Older Adults in the Emergency Department: A Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis to identify risk factors for delirium in geriatric patients in the emergency department and to identify emergency department (ED)-based modifiable risk factors for developing delirium during hospitalization. We searched evidence based medicine reviews, EMBASE, MEDLINE, Scopus, and Web of Science for observational studies from the time of their inception to July 2020. We included studies that evaluated potential risk factors for either prevalent or incident delirium among older adults (age ≥ 60 years) presenting to the ED. When appropriate, we meta-analyzed estimates for risk factors using a random-effects model. The certainty of evidence was evaluated using the grading of recommendations assessment, development and evaluation approach. The study's protocol was registered in PROSPERO (CDR42020175261). A total of 4,513 citations were reviewed, and 34 studies met the criteria for inclusion: 27 evaluating risk factors for ED delirium (13,412 patients) and 7 evaluating ED-based risk factors for developing delirium during hospitalization (2,238 patients). The prevalence of ED delirium ranged from 7% to 35%. Four factors had strong associations with ED delirium and were graded as high-certainty evidence, including nursing home residence (4 studies; odds ratio [OR], 3.45; 95% confidence interval [CI], 2.17 to 5.48), cognitive impairment (7 studies; OR, 4.46; 95% CI, 3.38 to 5.89), hearing impairment (3 studies, OR, 2.57; 95% CI, 1.03 to 6.41), and a history of stroke (3 studies; OR, 3.20; 95% CI, 1.17 to 8.75). The rate of developing delirium during hospitalization ranged from 11% to 27%. A length of stay of more than 10 hours in ED was associated with a higher risk of delirium (1 study; OR, 2.23; 95% CI, 1.13 to 4.41). One study reported that severe pain, rather than the use of opioids, was associated with the development of delirium. These findings can be used to prioritize delirium screening in the ED and develop novel ED delirium risk scores or prevention interventions.

Trends in Geriatric Emergency Medicine

Geriatric emergency medicine has emerged as a subspecialty of emergency medicine over the past 25 years. This emergence has seen the development of increases in training opportunities, care delivery strategies, collaborative best practice guidelines, and formal geriatric emergency department accreditation. This multidisciplinary field remains ripe for continued development in the coming decades as the aging US population parallels a call from patients, health care providers, and health systems to improve the delivery of high-value care. This article educates emergency medicine practitioners and highlights high-value care practice trends to inform and prioritize decision-making for this unique patient population.

Delirium in Emergency Departments: Is it Recognized?

BACKGROUND

Delirium is a complex neurocognitive manifestation of an underlying medical or surgical abnormality such as substance abuse, infection, sepsis, or organ failure. A recognized risk factor for delirium is advanced age (age >65 years). The projected demographic changes over the next 2 decades suggest that the number of aging adults will grow dramatically, and emergency nurses will see an increasing number of older patients manifesting the wide range of neuropsychiatric symptoms associated with delirium.

METHOD

An examination of 5 commonly used delirium assessment tools was undertaken specific to clinical features, use, scoring, findings, advantages, and disadvantages.

FINDINGS

Numerous factors contribute to the lack of effective delirium recognition. However, emergency nurses, with educational support, can successfully use the delirium assessment tools to recognize delirium.

CONCLUSION

Emergency nurses face challenges in recognizing delirium. One key challenge for many of these nurses is the appropriate use of assessment tools suitable for the ED setting.

Delirium Prevention, Detection, and Treatment in Emergency Medicine Settings: A Geriatric Emergency Care Applied Research (GEAR) Network Scoping Review and Consensus Statement

BACKGROUND

Older adult delirium is often unrecognized in the emergency department (ED), yet the most compelling research questions to overcome knowledge-to-practice deficits remain undefined. The Geriatric Emergency care Applied Research (GEAR) Network was organized to identify and prioritize delirium clinical questions.

METHODS

GEAR identified and engaged 49 transdisciplinary stakeholders including emergency physicians, geriatricians, nurses, social workers, pharmacists, and patient advocates. Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews, clinical questions were derived, medical librarian electronic searches were conducted, and applicable research evidence was synthesized for ED delirium detection, prevention, and management. The scoping review served as the foundation for a consensus conference to identify the highest priority research foci.

RESULTS

In the scoping review, 27 delirium detection "instruments" were described in 48 ED studies and used variable criterion standards with the result of delirium prevalence ranging from 6% to 38%. Clinician gestalt was the most common "instrument" evaluated with sensitivity ranging from 0% to 81% and specificity from 65% to 100%. For delirium management, 15 relevant studies were identified, including one randomized controlled trial. Some intervention studies targeted clinicians via education and others used clinical pathways. Three medications were evaluated to reduce or prevent ED delirium. No intervention consistently prevented or treated delirium. After reviewing the scoping review results, the GEAR stakeholders identified ED delirium prevention interventions not reliant on additional nurse or physician effort as the highest priority research.

CONCLUSIONS

Transdisciplinary stakeholders prioritize ED delirium prevention studies that are not reliant on health care worker tasks instead of alternative research directions such as defining etiologic delirium phenotypes to target prevention or intervention strategies.

The 4 'A's test for detecting delirium in acute medical patients: a diagnostic accuracy study

BACKGROUND

Delirium is a common and serious neuropsychiatric syndrome, usually triggered by illness or drugs. It remains underdetected. One reason for this is a lack of brief, pragmatic assessment tools. The 4 'A's test (Arousal, Attention, Abbreviated Mental Test - 4, Acute change) (4AT) is a screening tool designed for routine use. This project evaluated its usability, diagnostic accuracy and cost.

METHODS

Phase 1 - the usability of the 4AT in routine practice was measured with two surveys and two qualitative studies of health-care professionals, and a review of current clinical use of the 4AT as well as its presence in guidelines and reports. Phase 2 - the 4AT's diagnostic accuracy was assessed in newly admitted acute medical patients aged ≥ 70 years. Its performance was compared with that of the Confusion Assessment Method (CAM; a longer screening tool). The performance of individual 4AT test items was related to cognitive status, length of stay, new institutionalisation, mortality at 12 weeks and outcomes. The method used was a prospective, double-blind diagnostic test accuracy study in emergency departments or in acute general medical wards in three UK sites. Each patient underwent a reference standard delirium assessment and was also randomised to receive an assessment with either the 4AT (n = 421) or the CAM (n = 420). A health economics analysis was also conducted.

RESULTS

Phase 1 found evidence that delirium awareness is increasing, but also that there is a need for education on delirium in general and on the 4AT in particular. Most users reported that the 4AT was useful, and it was in widespread use both in the UK and beyond. No changes to the 4AT were considered necessary. Phase 2 involved 785 individuals who had data for analysis; their mean age was 81.4 (standard deviation 6.4) years, 45% were male, 99% were white and 9% had a known dementia diagnosis. The 4AT (n = 392) had an area under the receiver operating characteristic curve of 0.90. A positive 4AT score (> 3) had a specificity of 95% [95% confidence interval (CI) 92% to 97%] and a sensitivity of 76% (95% CI 61% to 87%) for reference standard delirium. The CAM (n = 382) had a specificity of 100% (95% CI 98% to 100%) and a sensitivity of 40% (95% CI 26% to 57%) in the subset of participants whom it was possible to assess using this. Patients with positive 4AT scores had longer lengths of stay (median 5 days, interquartile range 2.0-14.0 days) than did those with negative 4AT scores (median 2 days, interquartile range 1.0-6.0 days), and they had a higher 12-week mortality rate (16.1% and 9.2%, respectively). The estimated 12-week costs of an initial inpatient stay for patients with delirium were more than double the costs of an inpatient stay for patients without delirium (e.g. in Scotland, £7559, 95% CI £7362 to £7755, vs. £4215, 95% CI £4175 to £4254). The estimated cost of false-positive cases was £4653, of false-negative cases was £8956, and of a missed diagnosis was £2067.

LIMITATIONS

Patients were aged ≥ 70 years and were assessed soon after they were admitted, limiting generalisability. The treatment of patients in accordance with reference standard diagnosis limited the ability to assess comparative cost-effectiveness.

CONCLUSIONS

These findings support the use of the 4AT as a rapid delirium assessment instrument. The 4AT has acceptable diagnostic accuracy for acute older patients aged > 70 years.

FUTURE WORK

Further research should address the real-world implementation of delirium assessment. The 4AT should be tested in other populations.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN53388093.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 40. See the NIHR Journals Library website for further project information. The funder specified that any new delirium assessment tool should be compared against the CAM, but had no other role in the study design or conduct of the study.

Delirium risk in non-surgical patients: systematic review of predictive tools

OBJECTIVE

Delirium is a common, serious condition associated with poor hospital outcomes. Guidelines recommend screening for delirium risk to target diagnostic and/or prevention strategies. This study critically reviews multicomponent delirium risk prediction tools in adult non-surgical inpatients.

STUDY DESIGN

Systematic review of studies incorporating at least two clinical factors in a multicomponent tool predicting risk of delirium during hospital admission. Derivation and validation studies were included. Study design, risk factors and tool performance were extracted and tabulated, and study quality was assessed by CHARMS criteria.

DATA SOURCES

PubMed, Embase, PsycINFO, and Cumulative Index to Nursing Health Literature (CINAHL) to 11^th March 2018.

DATA SYNTHESIS

22 derivation studies enrolling 38,874 participants (9 with a validation component) and 4 additional validation studies were identified, from a range of ward types. All studies had at least moderate risk of bias. Older age and cognitive, functional and sensory impairment were important predisposing factors. Precipitating risk factors included infection, illness severity, renal and electrolyte disturbances. Tools mostly did not differentiate between predisposing and precipitating risk factors mathematically or conceptually Most tools showed fair to good discrimination, and identified more than half of older inpatients at risk.

CONCLUSIONS

Several validated delirium risk prediction tools can identify patients at increased risk of delirium, but do not provide clear advice for clinical application. Most recommended cut-points are sensitive but have low specificity. Implementation studies demonstrating how risk screening can better direct clinical interventions in specific clinical settings are needed to define the potential value of these tools.