Evidence-based Synthesis Program Department of Veterans Affairs

Health Services Research & Development Service Evidence-based Synthesis Program 

Delirium: Screening, Prevention, 

and Diagnosis – A Systematic Review 

of the Evidence

Department of Veterans Affairs

Health Services Research & Development Service

September 2011

Prepared for:

Department of Veterans Affairs

Veterans Health Administration

Health Services Research & Development Service

Washington, DC 20420

Prepared by:

Evidence-based Synthesis Program (ESP) Center

Minneapolis VA Medical Center

Minneapolis, MN

Timothy J. Wilt, MD, MPH, Director

Investigators:

Principal Investigator: 

Rebecca Rossom, MD, MSCR

Co-Investigators:

Pauline Anderson, RN 

Nancy Greer, PhD

Research Associates:

Roderick MacDonald, MS

Indulis Rutks, BS

James Tacklind, BS
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Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

PREFACE

Health Services Research & Development Service’s (HSR&D’s) Evidence-based Synthesis 

Program (ESP) was established to provide timely and accurate syntheses of targeted healthcare 

topics of particular importance to Veterans Affairs (VA) managers and policymakers, as they 

work to improve the health and healthcare of Veterans. The ESP disseminates these reports 

throughout VA.

HSR&D provides funding for four ESP Centers and each Center has an active VA affiliation. The 

ESP Centers generate evidence syntheses on important clinical practice topics, and these reports 

help:

• develop clinical policies informed by evidence,

• guide the implementation of effective services to improve patient outcomes and to 

support VA clinical practice guidelines and performance measures, and 

• set the direction for future research to address gaps in clinical knowledge.

In 2009, the ESP Coordinating Center was created to expand the capacity of HSR&D Central 

Office and the four ESP sites by developing and maintaining program processes. In addition, 

the Center established a Steering Committee comprised of HSR&D field-based investigators, 

VA Patient Care Services, Office of Quality and Performance, and Veterans Integrated Service 

Networks (VISN) Clinical Management Officers. The Steering Committee provides program 

oversight, guides strategic planning, coordinates dissemination activities, and develops 

collaborations with VA leadership to identify new ESP topics of importance to Veterans and the 

VA healthcare system.

Comments on this evidence report are welcome and can be sent to Nicole Floyd, ESP 

Coordinating Center Program Manager, at nicole.floyd@va.gov.

Recommended citation: Greer N, Rossom R, Anderson P, MacDonald R, Tacklind J, Rutks 

I, Wilt TJ. Delirium: Screening, Prevention, and Diagnosis - A Systematic Review of the 

Evidence. VA-ESP Project #09-009; 2011.

This report is based on research conducted by the Evidence-based Synthesis 

Program (ESP) Center located at the Minneapolis VA Medical Center, 

Minneapolis, MN funded by the Department of Veterans Affairs, Veterans Health 

Administration, Office of Research and Development, Health Services Research 

and Development. The findings and conclusions in this document are those of 

the author(s) who are responsible for its contents; the findings and conclusions 

do not necessarily represent the views of the Department of Veterans Affairs 

or the United States government. Therefore, no statement in this article should 

be construed as an official position of the Department of Veterans Affairs. No 

investigators have any affiliations or financial involvement (e.g., employment, 

consultancies, honoraria, stock ownership or options, expert testimony, grants or 

patents received or pending, or royalties) that conflict with material presented in 

the report.
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Delirium: Screening, Prevention, and Diagnosis – 

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TABLE OF CONTENTS

EXECUTIVE SUMMARY

Background.................................................................................................................................................... 1

Methods......................................................................................................................................................... 2

Data Synthesis............................................................................................................................................... 2

Peer Review................................................................................................................................................... 2

Results ........................................................................................................................................................... 2

Future Research............................................................................................................................................. 4

INTRODUCTION

Background.................................................................................................................................................... 5

METHODS

Topic Development........................................................................................................................................ 6

Search Strategy.............................................................................................................................................. 8

Study Selection.............................................................................................................................................. 8

Data Abstraction ............................................................................................................................................ 8

Quality Assessment ....................................................................................................................................... 8

Data Synthesis............................................................................................................................................... 9

Rating the Body of Evidence......................................................................................................................... 9

Peer Review................................................................................................................................................... 9

RESULTS

Literature Flow ............................................................................................................................................ 10

Key Question #1. What is the effectiveness of screening for delirium in adult inpatients? .................... 12

a. Do these results vary by medical unit, age, gender or comorbid conditions? ....................... 14

b. Does screening for delirium improve clinical outcomes?...................................................... 14

Key Question #2. What are the effectiveness and harms of delirium prevention strategies in 

acute elderly inpatients? ........................................................................................................... 14 

a. Do these results vary by medical unit, age, gender or comorbid conditions?........................ 32

Key Question #3. What is the comparative diagnostic accuracy of the tools used to detect delirium? .... 33

a. In elderly medical and surgical inpatients? .......................................................................... 33 

b. In elderly ICU inpatients?...................................................................................................... 36

SUMMARY AND DISCUSSION

Summary of Evidence by Key Question ..................................................................................................... 40

Recommendations for Future Research....................................................................................................... 41

Conclusions ................................................................................................................................................. 42

REFERENCES ................................................................................................................................................... 43
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Delirium: Screening, Prevention, and Diagnosis – 

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TABLES

Table 1. Summary of Study Baseline Characteristics for Delirium Prevention Studies.......................... 15

Table 2. Incidence of Delirium - Pharmacologic Prevention Studies...................................................... 17

Table 3. Evidence Summaries for the Randomized Pharmacologic Delirium Studies: Incidence of 

Delirium..................................................................................................................................... 21

Table 4. Components of Multi-Component Interventions for Delirium Prevention................................ 24

Table 5. Incidence of Delirium - Non-Pharmacologic or Mixed Treatments Prevention Studies........... 25

Table 6. Evidence Summaries for the Randomized Non-pharmacologic Delirium Studies: Incidence 

of Delirium................................................................................................................................. 26

Table 7. Adverse Events and Mortality – Prevention Studies ................................................................. 28

Table 8. Outcomes – Intensive Care Unit Diagnostic Accuracy Studies................................................. 38

FIGURES

Figure 1. Analytic Framework .................................................................................................................... 7

Figure 2. Flow Diagram – Delirium Screening Studies............................................................................ 10

Figure 3. Flow Diagram – Delirium Prevention Studies........................................................................... 11

Figure 4. Flow Diagram – Delirium ICU Diagnosis Studies.................................................................... 11

Figure 5. Incidence of Delirium, Randomized Pharmacologic Trials....................................................... 20

APPENDIX A. Search Strategies.............................................................................................................. 52

APPENDIX B. Study Selection Form ..................................................................................................... 54

APPENDIX C. Peer Review Comments/Author Responses ............................................................ 55

APPENDIX D. Evidence Tables

Table 1. Characteristics of Pharmacologic Prevention Studies.................................................................. 61

Table 2. Primary Prevention Outcomes of Pharmacologic Studies............................................................ 71

Table 3. Characteristics of Non-Pharmacologic or Mixed Treatments Prevention Studies ....................... 74

Table 4. Primary Prevention Outcomes of Non-Pharmacologic or Mixed Studies.................................... 84

Table 5. Characteristics of Intensive Care Unit Diagnostic Accuracy Studies........................................... 88
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Delirium: Screening, Prevention, and Diagnosis – 

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EVIDENCE REPORT

INTRODUCTION

This review was undertaken to evaluate the effectiveness of screening for delirium in adult 

inpatients, the effectiveness of strategies employed to prevent delirium in acute elderly 

inpatients, and the comparative diagnostic accuracy of tools used to detect delirium in elderly 

medical, surgical, and ICU patients. 

For this review, we were careful to make the important distinction between screening for 

delirium (testing all patients for delirium without a prior index of suspicion) and diagnosis of 

delirium (testing those patients for whom there is already some suspicion of delirium).

BACKGROUND

Delirium is a common syndrome, characterized by the acute onset of altered mental status, 

hallmarked by difficulty sustaining attention and a fluctuating course, and frequently causing 

patients, families, and health care providers considerable distress. There have been wide 

variations in the reported incidence of delirium in medical inpatients, largely due to differences 

in setting, patient population, and methodology. It has been estimated that 10-30% of patients 

admitted to the hospital develop delirium;9,10 this percentage can increase significantly in at-risk 

populations, including frail elderly patients (estimated at 60%),11 post-surgical elderly patients 

(estimated as high as 89%),12 or ICU patients (estimated at 41%).13

Delirium has been associated with multiple serious outcomes in medically ill patients, including 

increased morbidity, length of stay, healthcare costs, institutionalization, and mortality.2,3,14-16

Delirium is often significantly under-recognized by healthcare providers and can frequently 

be difficult to resolve.5,6,17,18 Several brief “bedside” questionnaires and checklists exist that 

can detect delirium earlier and among those with milder symptoms. Efforts to prevent the 

development of delirium in those at risk have been advocated.3,6 Medications (including 

sedatives, narcotics, and anticholinergic drugs), diseases and intercurrent illnesses (e.g., stroke, 

infection, shock, anemia), surgical procedures (especially orthopedic and cardiac surgery), 

and environmental factors (e.g., use of a bladder catheter, pain, and emotional stress) are all 

precipitating factors for delirium development.6,7 Therefore, identifying and implementing 

effective strategies to prevent and detect delirium could improve clinical outcomes and 

resource utilization. Suggested strategies to prevent delirium include avoidance of psychoactive 

medications, pharmacologic interventions to decrease risk, and single- or multi-component 

non-pharmacologic interventions (including use of music, mobilization, fluid and nutrition 

management, and orientation and cognitive stimulation).4,6,7
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Delirium: Screening, Prevention, and Diagnosis – 

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METHODS

TOPIC DEVELOPMENT

This project was nominated by Nancy Schmid, ADPNS, a Nurse Executive at Syracuse 

VA Medical Center, with input from a technical expert panel of clinicians, researchers, and 

administrators. 

The final key questions are:

1. What is the effectiveness of screening for delirium in adult inpatients? 

a. Do these results vary by medical unit, age, gender or comorbid conditions? 

b. Does screening for delirium improve clinical outcomes? 

2. What are the effectiveness and harms of delirium prevention strategies in acute elderly 

inpatients? 

a. Do these results vary by medical unit, age, gender or comorbid conditions?

3. What is the comparative diagnostic accuracy of the tools used to detect delirium:

a. In elderly medical and surgical inpatients?

b. In elderly medical or surgical intensive care unit (ICU) inpatients?

An analytic framework (Figure 1) was developed to depict the potential pathway of a 

hospitalized adult patient. This report will focus on the outcomes and harms associated with 

screening (Key Question #1), preventive interventions (Key Questions #2), and diagnosis (Key 

Question #3).
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, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

rk

Diagnosis of Delirium (KQ3)

Intermediate Outcomes:Change in mental status

Clinical Outcomes:Length of Stay (Hospital, ICU)Ventilator timeMortalityTime to TransferADL/IADLTime to return to baselineInstitutionalization

No Delirium

KQ2 Preventive Intervention

ve Intervention

Harms of Preventive Interventions:Resource utilizationUnnecessary intervention

: 

 

KQ1 Screening

Treatment

Harms of Treatment:Resource utilizationUnnecessary treatment
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Delirium: Screening, Prevention, and Diagnosis – 

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SEARCH STRATEGY

We searched MEDLINE, CINAHL, and PsycINFO from 1950 to November 2010 using standard 

search terms (Appendix A). We limited the search to peer-reviewed articles involving human 

subjects and published in the English language. Additional citations were identified from 

reference lists and Technical Expert Panel members. 

STUDY SELECTION

Physicians, nurses, and research assistants trained in the critical analysis of literature assessed 

for relevance the abstracts of citations identified from literature searches. Full-text articles 

of potentially relevant abstracts were retrieved for further review. A Study Selection Form 

(Appendix B) was used to guide this review.

Specific exclusion criteria for the screening and diagnosis questions were as follows:

1) Non-English publication

2) Population <16 yrs old 

3) Alcohol-related delirium

4) Not hospitalized patients (nursing home or similar was excluded)

5) No reference standard (DSM III, III-R, or IV)

6) Index test and reference standard performed by same individual

7) Case series (<10 patients), case report, editorial, letter

8) Not patients with delirium

9) No outcomes of interest

10) Not a screening or diagnosis study 

Specific exclusion criteria for the prevention question were as follows:

1) Non-English publication

2) Population <16 years old

3) Nursing home residents (or mixed hospital/nursing home if unable to get results of hospital 

only)

4) Case series, case report, editorial, letter

5) Not about delirium prevention

DATA ABSTRACTION 

Study characteristics, patient characteristics, and outcomes were extracted and evidence and 

outcomes tables, organized by key question, were created under the supervision of the Principal 

Investigator, a geriatric psychiatrist. 

QUALITY ASSESSMENT

We assessed study quality of randomized trials of prevention strategies (Key Question 2) 

according to the following criteria: 1) adequate allocation concealment, 2) blinding of key study 

personnel, 3) analysis by intention-to-treat, and 4) reporting of number of withdrawals/dropouts 

by group assignment.19 Studies were rated as good, fair, or poor quality. A rating of good 
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Delirium: Screening, Prevention, and Diagnosis – 

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generally indicated that the trial reported adequate allocation concealment, blinding, analysis by 

intent-to-treat, and reasons for dropouts/attrition were reported. Studies were generally rated poor 

if the method of allocation concealment was inadequate or not defined, blinding was not defined, 

analysis by intent-to-treat was not utilized, and reasons for dropouts/attrition were not reported 

and/or there was a high rate of attrition.

Study quality of studies reported for Key Question 3 (studies of diagnostic accuracy) was 

assessed using the method described in the Rationale Clinical Examination series.8

 Briefly, 

studies are designated as Level of Evidence 1 if they present an independent, blinded comparison 

with a criterion standard in a large number (defined as 100 or more patients in the delirium 

diagnosis review) of consecutive individuals suspected of having the target condition or a 

Level of Evidence 2 if they meet all the criteria for Level 1 but enroll fewer than 100 patients. 

Level of Evidence 3 studies are similar to Level 1 or Level 2 studies but do not enroll patients 

consecutively. Studies with a non-independent comparison with the criterion standard and that 

enroll (at least in part) patients who obviously have the target condition are designated as Level 

of Evidence 4. Studies with a reference test of questionable validity are designated Level of 

Evidence 5.

DATA SYNTHESIS

We constructed evidence tables showing the study characteristics and results for all 

included studies, organized by key question. We critically analyzed studies to compare their 

characteristics, methods, and findings. Pooled analyses were performed, where feasible, for 

studies of prevention strategies. All other data were narratively summarized.

RATING THE BODY OF EVIDENCE

We assessed the overall quality of evidence for randomized trials of prevention strategies (Key 

Question #2) using the method reported by Owens et al.20 Briefly, for each outcome evaluated, 

the strength of the evidence was assessed based on: (1) risk of bias; (2) consistency; (3) 

directness; and (4) precision. Based on these four domains, the overall evidence was rated as: (1) 

high, meaning high confidence that the evidence reflects the true effect; (2) moderate, indicating 

moderate confidence that further research may change our confidence in the estimate of effect 

and may change the estimate; (3) low, meaning there is low confidence that the evidence reflects 

the true effect; and (4) insufficient, indicating that evidence either is unavailable or does not 

permit a conclusion. Due to heterogeneity in the interventions evaluated, we did not rate the 

overall strength of evidence for the non-randomized trials.

PEER REVIEW

A draft version of this report was reviewed by technical experts and VA clinical leadership. Their 

comments and our responses are presented in Appendix C.
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Delirium: Screening, Prevention, and Diagnosis – 

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RESULTS

LITERATURE FLOW

For the screening question, we identified 1,889 abstracts and excluded 1,778. We reviewed the 

full text of 111 references and none met inclusion criteria. 

For the prevention question, we identified 1,175 abstract and excluded 947. Of 228 full text 

articles reviewed, 31 met eligibility criteria. We added 8 references from hand-searching for 

a total of 39 included references. In addition to our literature search, we identified one recent 

Cochrane systematic review of delirium prevention21 and a recent National Institute for Health 

and Clinical Excellence (NICE) guideline on diagnosis, prevention, and management of 

delirium.7,22 Five of the six randomized controlled trials included in the Cochrane review are 

included in our analysis. The sixth trial, a study of prophylactic citicoline (a psychostimulant) 

versus placebo, was published in Spanish language and was therefore not eligible for our review. 

The authors reported no difference in delirium incidence.23

The NICE guideline cited seven studies of pharmacologic prevention strategies, five studies of 

non-pharmacologic strategies, and eight studies of multi-component interventions. Six of the 

pharmacologic studies, one of the non-pharmacologic studies, and seven of the multi-component 

studies met our inclusion criteria and are included in our analysis. The remaining studies were 

either not conducted in a hospital setting or did not provide data on outcomes of interest. 

For the question about diagnostic accuracy, our search was limited to studies of patients admitted 

to intensive care units. We identified 76 abstracts and excluded 40 of those. Of 36 full text articles 

reviewed, 15 met inclusion criteria. Figures 2, 3, and 4 present the literature search results.

Figure 2. Flow Diagram – Delirium Screening Studies

Search results = 1889 references

Pulled for full text review = 111 

references

Included studies = 0 references

Excluded = 111 references

Not relevant to key question = 111 

references

Excluded = 1778 references

Not English language = 1

Patients less than 16 years old = 17

Alcohol-related delirium = 6

Not hospitalized patients = 13

No reference standard = 1

Case series, case report, editorial, 

letter, book, dissertation = 30

Not delirium = 1696

No outcomes of interest = 2

Not screening/diagnosis study = 12
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Delirium: Screening, Prevention, and Diagnosis – 

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Figure 3. Flow Diagram – Delirium Prevention Studies

Excluded = 947 references

Subjects less than 16 years old = 26

Nursing home residents = 25

Case series, case report, editorial, 

letter, book, dissertation = 249

Not delirium = 498

No outcomes of interest = 117

Duplicate reference = 25

Not prevention = 5

Not English language = 2

Pulled for full text review = 228 

references

Eligible studies = 31 references

Handsearched references = 8 

references

Included studies = 39 references

Excluded = 197 references

Not relevant to key question = 197

Search results = 1175 references

Figure 4. Flow Diagram – Delirium ICU Diagnosis Studies

Search results = 76 references

Pulled for full text review = 36 

references

Excluded = 21 references

Not relevant to key question = 21

Included studies = 15 references

Excluded = 40 references

Patients less than 16 years old = 1

Alcohol-related delirium = 1

Case series, case report, letter, 

editorial = 1

Not delirium = 21

No outcomes of interest = 2

Not screening or diagnosis = 9

Duplicate = 2

Not ICU = 3
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Delirium: Screening, Prevention, and Diagnosis – 

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KEY QUESTION #1. What is the effectiveness of screening for delirium 

in adult inpatients? 

Screening for a disease or condition is warranted if the disease is serious, if treatment before 

symptoms are evident reduces morbidity and mortality, and if the prevalence of preclinical 

disease is high among the population screened.24 In addition, the screening test should identify 

most or all with the condition, be cost effective and ethical, be easy to administer, and impose 

minimal discomfort on patients. The test must also be reliable, valid, and reproducible.25

Based on the criteria above, screening for delirium may be appropriate. However, we did not 

identify any studies comparing patient outcomes in hospitalized (including intensive care unit) 

patients randomly assigned to screening or no screening for delirium. 

In the absence of direct evidence we look for indirect links between screening and outcomes. To 

indirectly link screening and outcomes, we would need evidence that 1) patients with delirium 

have worse outcomes, 2) systematic screening would improve detection of delirium, 3) treatments 

for detected delirium are effective, particularly if delirium can be detected early, and 4) harms 

associated with screening are minimal. A systematic review for this evidence is beyond the scope of 

this report. We report results from recent existing systematic reviews where available.

Outcomes in Patients with Delirium

A 2006 systematic review reported outcomes from 19 study cohorts.26 Study design, diagnostic 

method, patient selection criteria, comorbid conditions, length of follow-up, outcome 

measurement, and adjustment (or lack of adjustment) for potential confounders varied among 

the studies making conclusions difficult. Overall, there appeared to be increased mortality in 

patients with delirium. Results for hospital length of stay, resolution of symptoms at discharge, 

institutionalization at discharge, and functional ability at discharge were less consistent. 

Improved Detection

If all hospitalized patients or all patients at increased risk were screened for delirium, detection 

would be expected to increase. However, we did not identify any systematic reviews on detection 

rates with screening.

Treatment

A search of the literature identified several recent systematic reviews that focused on treatment. 

A 2007 Cochrane review included data from 3 randomized trials that compared antipsychotic 

medications used to treat delirium.27 No differences in patient outcomes or adverse events were 

found between low-dose haloperidol, risperidone, and olanzapine. A second review included 14 

studies, 9 single-agent and 5 comparative.28 None of the studies included a placebo control group 

and the total sample size was 448. Although most subjects experienced improvements in delirium 

severity, without a blinded placebo comparison group it is impossible to determine the role of 

the study medication in the observed improvement. Few serious adverse events were reported. 

A third review included 4 randomized studies of pharmacologic management.29 The conclusions 

were similar. A fourth review included non-pharmacological and pharmacological treatments.30

Regarding non-pharmacological approaches, the authors noted that few studies have focused on 
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Delirium: Screening, Prevention, and Diagnosis – 

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the efficacy of cognitive, emotional, or environmental interventions although they are widely used. 

They also noted the paucity of high-quality randomized trials of pharmacological interventions 

Harms

No systematic reviews have identified harms associated with screening. Potential harms include 

misclassification resulting in patients either receiving unnecessary treatment or failing to receive 

potentially beneficial treatment. There is also the potential for psychological harm for the patient 

and their family when patients are misclassified. Screening tools, such as the Confusion Assessment 

Method (CAM), are not invasive and require little of the patient’s or provider’s time or effort. 

Although cost-effectiveness is beyond the scope of this review, costs to the health care system 

associated with administering and following up on screening test results should be considered.

Recommendations of Others

Despite the lack of direct evidence of a benefit of screening, some organizations have 

developed guidelines that recommend screening of patients or targeted screening of patients 

considered at risk for delirium. The 2010 National Institute for Health and Clinical Excellence 

(NICE) guideline on diagnosis, prevention, and management of delirium recommends 

assessment of risk factors for delirium in all patients when they first present to a hospital 

and observation of people admitted to a hospital at every opportunity for changes in the risk 

factors for delirium.7.31 Risk factors cited include age 65 and older, cognitive impairment 

(past or present) and/or dementia, current hip fracture, and severe illness (defined as a clinical 

condition that is deteriorating or at risk of deteriorating). The recommendation is based on 

low and moderate quality evidence from prospective cohort studies. Guidelines developed 

by the Delirium Guidelines Development Group (Switzerland) call for “routine screening of 

cognitive functions and delirium, whenever possible, using standardized instruments,” notably 

the Mini-Mental State Examination (MMSE) or Blessed Orientation-Memory-Concentration 

(BOMC) tests on admission and the CAM during the hospital stay. Particular emphasis 

was given to systematic screening in at-risk patients. The authors noted the relative lack of 

evidence supporting the consensus statements.32 The British Geriatrics Society guidelines 

include a recommendation to identify all patients over 65 years with cognitive impairment 

on admission.33 Delirium should be considered in patients with cognitive impairment and at 

high risk due to severe illness, dementia, fracture of the femoral neck, and visual and hearing 

impairment. Serial assessments are recommended in those patients to help detect the new 

development of delirium. This recommendation was based on evidence from high quality 

systematic reviews or cohort studies or extrapolated evidence from meta-analyses, systematic 

reviews, or randomized trials. The Australian clinical practice guideline on management of 

delirium recommends establishment of a structured process for screening and diagnosis of 

delirium in all health care settings.25 The recommended process includes assessment of risk 

of delirium and cognitive function at admission with repeat testing of high risk patients (age 

70 or older, pre-existing cognitive impairment, severe medical illness, depression, abnormal 

sodium, and visual impairment) and further assessment for delirium and/or referral if there is a 

decline in the cognitive assessment score. The recommendations were based on expert opinion. 

Clinical practice guidelines from the American College of Critical Care Medicine of the 

Society of Critical Care Medicine recommend routine assessment for the presence of delirium, 
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including ICU patients.34 The recommendation was graded B (defined as methods strong, 

results inconsistent, prospective randomized controlled trials with heterogeneity present).

Key Question 1a. Do these results vary by medical unit, age, gender or comorbid 

conditions?

We did not find any direct evidence that screening is effective regardless of the medical unit, age 

or gender of the patients, or their comorbid conditions.

Key Question 1b. Does screening for delirium improve clinical outcomes?

We did not find any evidence that screening for delirium improves clinical outcomes in 

hospitalized (including ICU) patients.

Conclusions

We identified no randomized-controlled trials of screening for delirium in hospitalized patients. 

We identified several studies that have compared the diagnostic accuracy of a screening tool to 

an established reference standard (validation studies). Most of these reports focused on selected 

subsets of hospitalized patients who were at high risk for delirium. Results from those studies 

are reported in Key Question 3. In addition, there have been many application studies (i.e., 

evaluating patients at admission and during their hospital stay and reporting on prevalent [present 

at the time of admission] and incident [developed during hospitalization] cases of delirium). A 

recent systematic review summarizes validation, adaptation, translation, and application studies 

for the CAM.35

Unfortunately, these types of studies do not address the question of whether screening for 

delirium in asymptomatic individuals improves patient outcomes nor do they directly assess 

the potential harms associated with universal screening. Therefore, the available evidence is 

insufficient to make recommendations about the net benefit of delirium screening among all 

hospitalized patients or patients admitted to intensive care units. 

KEY QUESTION #2. What are the effectiveness and harms of delirium 

prevention strategies in acute elderly inpatients? 

Predisposing and precipitating factors for delirium have been well documented.4,6,36 Predisposing 

factors include poor nutrition, dehydration, alcohol or drug abuse, medication use (especially use 

of sleep medications, narcotic pain relievers, anticholinergics, sedative hypnotics, anti-depressants, 

Parkinson’s disease treatments, anti-convulsants, muscle relaxants, and allergy medications), 

impaired vision or hearing, sleep deprivation, and low level of activity. Precipitating factors include 

infection, alcohol or drug withdrawal, emotional stress, multiple medical procedures, pain, and 

electrolyte disturbances. Prevention strategies typically target one or more of these factors.

Summary of Studies for Key Question 2

The study design, population and study characteristics and quality and outcomes evaluated for 

each of the included studies are presented in Table 1 and Appendix D, Tables 1 and 3. 
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Delirium: Screening, Prevention, and Diagnosis – 

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Study design and location

Thirty-nine unique studies on prevention of delirium enrolling between 15 and 1059 subjects met 

inclusion for Key Question 2. A total of 7935 subjects were enrolled in these 39 studies. 

Twenty studies evaluated pharmacologic methods for preventing delirium; sixteen of these 

were randomized,13,37-51 while four were non-randomized studies.12,52-54 Five studies evaluated 

cholinesterase inhibitors,12,40,45,47,54 while four examined anesthesia,39,41,48,51 three examined 

analgesic agents, 13,43,53 four examined antipsychotic medications, 38,44,46,50 and one each examined 

melatonin,37 benzodiazepines,49 post-operative sedation,42 and a lipid-lowering agent.52

Nineteen studies (in 24 publications) evaluated non-pharmacologic or mixed methods of 

preventing delirium; five of these were randomized55-59 and fourteen were non-randomized.60-78

The majority of these studies evaluated multi-component interventions, often combined with staff 

education.55,58-67,69-78 The multi-component interventions varied greatly and included such components 

as geriatric consultation, individual care planning, focused prevention of infection, improving 

mobility, frequent orientation, bowel and bladder care regimens, insomnia protocols, adequate pain 

management, minimizing psychoactive or sedating medications, and maintaining adequate hydration 

and nutrition, among others. Other non-pharmacologic studies examined bright light therapy,56 the 

use of music,57 or the use of staff education alone68 as strategies for preventing delirium.

Of the 39 prevention studies of delirium,16 were conducted in Europe, 14 in the United States, 4 

in Japan, 2 in Australia, , 2 in Canada and 1 in Thailand. 

Table 1. Summary of Study Baseline Characteristics for Delirium Prevention Studies 

Characteristic

Mean (range)

Unless otherwise 

noted

Number of

trials

reporting

Total number of patients evaluated 7935 (15 to 1059) 39

% of patients (n/N) in randomized pharmacologic intervention studies 28 (2245/7935) 16

% of patients (n/N) in non-randomized pharmacologic intervention studies 17 (1311/7935) 4

% of patients (n/N) in randomized non-pharmacologic intervention studies 11 (866/7935) 5

% of patients (n/N) in non-randomized non-pharmacologic intervention studies 44 (3513/7935) 14

Age of subjects, years 78 (58 to 85) 33

Gender, male, % 44 (19 to 100) 34

Race/ethnicity, white, % 91 (87 to 98) 5

Orthopedics/orthopedic surgery, % of patients (n/N) 33 (2626/7935) 15

Cardiac surgery, % of patients (n/N) 19 (1481/7935) 5

Other surgery, % of patients (n/N) 8 (673/7935) 8

Internal medicine/geriatrics/other, % of patients (n/N) 40 (3155/7935) 11

Studies conducted in the US/Canada, % of patients (n/N) 53 (4253/7935) 16

Studies conducted in Europe, % of patients (n/N) 40 (3161/7935) 16

Studies conducted in Asia/Australia, % of patients (n/N) 7% (521/7935) 7
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Delirium: Screening, Prevention, and Diagnosis – 

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Patient characteristics

One of the included studies enrolled U.S. veterans.41 The mean age of the patients included 

in the 33 prevention studies that reported age was 78 years (range 58 to 85). Twenty-one 

studies enrolled only patients age 65 or greater. Men comprised 44% of subjects (range 

18%-100) in the 34 studies that reported gender. Only five studies reported racial or ethnic 

characteristics;38,41,47,59,71 the vast majority of subjects in those five studies were Caucasian (91%, 

range 87% to 98%). Twenty-eight of the studies involved patients on post-surgical units,13,37-57,59,6

0,66,69,70,76 ten involved patients on medicine wards,12,58,61,63,65,67,68,71,77,78 and one involved patients on 

medical-surgical units.62

Outcome measures

Outcomes reported varied widely between delirium prevention studies included in this report 

(Appendix D, Tables 2 and 4). All reported delirium incidence, with rates of delirium ranging 

from 11% to 88.9% in controls. Nine studies reported data regarding delirium severity. Fourteen 

studies reported data on delirium duration. Twenty-two studies reported data on hospital length 

of stay. Seven studies reported data regarding use of rescue medications.

Study quality

Most included studies assessing prevention measures utilized methods to reduce sources of bias 

(Appendix D, Tables 1 and 3). However, 11 studies did not report clear allocation concealment 

when concealment was possible. Thirteen studies did not utilize an intention-to-treat analysis 

(or were unclear in reporting) in studies where this would have been possible. Most studies 

adequately reported withdrawals from the study when this was appropriate, but three studies that 

would have been appropriate to report withdrawals did not do so.

Effectiveness

Pharmacologic Studies

Twenty studies evaluated pharmacologic interventions (Table 2, Appendix D, Tables 1 and 2). 

Most interventions were only assessed in single studies that were small in size. All but two 

studies12,37 involved post-surgical patients. While all studies reported incidence, 6 reported a 

measure of delirium severity, 7 reported delirium duration, 11 reported length of stay, and 5 

reported use of rescue medications (Appendix D, Table 2). Table 2 lists studies by intervention 

and provides incidence/prevalence data and relative risks.
17

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

 - Pharmacologic Prevention Studies

Study Study Type/Patients Intervention

Control

Delirium Incidence/ 

Prevalence % (n/N)

Relative Risk [95% 

Confidence Interval]

00547 RCT/orthopedic

Donepezil 21 (8/39)

Placebo 17 (7/41) 1.20 [0.48 to 3.00]

, 200745 RCT/orthopedic

Donepezil 11 (2/19)

Placebo 36 (5/14) 0.29 [0.07 to 1.30]

ni, 200940 RCT/cardiac surgery

Rivastigimine 32 (18/56)

Placebo 30 (17/57) 1.08 [0.62 to 1.87]

erg, 200412

Non-randomized/geriatric medicine

Rivastigmine 46 (5/11)

No Rivastigmine 89 (26/29) 0.51 [0.26 to 0.98]

197854

Non-randomized/elective surgery

Physostigmine 9 (4/45)

No Physostigmine 43 (29/68) 0.21 [0.08 to 0.55]

t, 200546 RCT/orthopedic

Haloperidol 15 (32/212)

Placebo 17 (36/218) 0.91 [0.59 to 1.42]

199150 RCT/gastrointestinal

Haloperidol 11 (4/38)

Placebo 33 (13/40) 0.32 [0.12 to 0.91]

01038 RCT/orthopedic

Olanzapine 14 (28/196)

Placebo 40 (82/204) 0.36 [0.24 to 0.52]

ttana, 200744 RCT/cardiac surgery

Risperidone 11 (7/63)

Placebo 32 (20/63) 0.35 [0.16 to 0.77]

ous, 200943 RCT/orthopedic

Fascia iliaca compartment block 11 (11/102)

Placebo 24 (25/105) 0.45 [0.24 to 0.87]

Russo, 199213 RCT/orthopedic

Continuous epidural 38 (10/26)

Continuous intravenous analgesia 44 (11/25) 0.87 [0.45 to 1.69]

rio, 200853

Non-randomized/orthopedic

Patient controlled, femoral nerve 8 (4/49)

Intravenous 42 (21/50) 0.19 [0.07 to 0.53]

nou, 200548 RCT/elective surgery

Regional (spinal or epidural) 16 (3/19)

General 21 (6/28) 0.74 [0.21 to 2.59]

, 198751 RCT/orthopedic

Epidural 50 (14/28)

General 38 (11/29) 1.32 [0.73 to 2.39]

01039 RCT/orthopedic

Light sedation 19 (11/57)

Deep sedation 40 (23/57) 0.48 [0.26 to 0.89]

00941 RCT/cardiac surgery

Adjuvant Ketamine (during induction) 3 (1/29)

Placebo 31 (9/29) 0.11 [0.02 to 0.82]

do, 200942 RCT/cardiac surgery

Dexmedetomidine 10 (4/40)

Propofol 44 (16/36) 0.23 (0.08 to 0.61)

do, 200942 RCT/cardiac surgery

Dexmedetomidine 10 (4/40)

Midazolam 43 (17/40) 0.24 (0.09 to 0.64)

200249 RCT/gastrointestinal 

Benzodiazepines+Pethidine 5 (1/20)

Usual care 35 (7/20) 0.14 (0.02 to 1.06)

 201137 RCT/internal medicine

Melatonin 11 (7/61)

Placebo 31 (19/61) 0.37 (0.17 to 0.81)

on, 200952

Non-randomized/cardiac surgery

Statin 11 (73/676)

No statin 13 (49/383) 0.84 [0.60 to 1.19]
18

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

Of the five studies evaluating cholinesterase inhibitors, two non-randomized trials found that 

using cholinesterase inhibitors was an effective strategy for decreasing the incidence of delirium. 

One study compared hospitalized patients who were chronic users of rivastigmine to non-users 

and found a decreased incidence of delirium in the chronic users (N=40, 45.5% vs. 88.9%, 

p=0.007).12 The second study compared delirium incidence in elective surgery patients given 

physostigmine or placebo (N=113, 28.9% vs. 69.1%, p=0.0004).54 Three randomized, controlled 

trials found no difference in delirium incidence between intervention and control subjects using 

rivastigmine in cardiac surgery patients (N=120, 32.1% vs. 29.8%, p=0.79)40 or donepezil in hip 

replacement patients (N=50, 10.5% vs. 35.7%, p=0.08)45 and hip and knee replacement patients 

(N=80, 20.5% vs. 17.1%, p=0.69).47 There were no reported differences between intervention and 

control groups in delirium severity, delirium duration, hospital length of stay, or use of rescue 

medications. 

Four studies looked at different anesthesia protocols. One study found that limiting the depth of 

intra-operative sedation during spinal anesthesia for hip fracture repair decreased the incidence 

of delirium in subjects receiving light sedation vs. subjects receiving deep sedation (N=114, 19% 

vs. 40%, p=0.02).39 This intervention was also found to decrease delirium duration (0.5 days (SD 

1.5) vs. 1.4 days (SD 4.0), p=0.01), but did not have a significant effect on delirium severity or 

hospital length of stay. In veterans undergoing elective cardiac surgery with cardiopulmonary 

bypass, ketamine (vs. saline) during anesthetic induction significantly reduced the incidence 

of delirium (N=58, 3.4% vs. 31.0%, p=0.01)41 Length of stay did not differ. A small, single 

site study comparing regional (epidural or spinal) anesthesia to general anesthesia in patients 

undergoing elective orthopedic or vascular surgery found no difference in the incidence of 

delirium (N=47, 15.8% vs. 21.4%, p=0.63).48 Similarly, in another small study there was no 

significant difference in the incidence of delirium in patients receiving epidural vs. general 

anesthesia during femoral neck fracture repair (N=57, 50% vs. 27.9%, p=0.36).51

Of the four studies evaluating antipsychotic medications, all involved surgical patients. 

Three found a significantly lower incidence of delirium in the intervention groups compared 

to the control groups38,44,50 The studies all compared use of prophylactic antipsychotics to 

that of placebo; one used olanzapine perioperatively in patients undergoing total knee or hip 

replacement (N=495, 14.3% vs. 40.2%, p<0.0001),38 one used risperidone following elective 

cardiac surgery with cardiopulmonary bypass (N=126, 11.1% vs. 31.7%, p=0.009),44 and one use 

haloperidol following gastrointestinal surgery(N=80, 10.5% vs 32.5%, p<0.05).50 A more recent 

study of haloperidol for patients undergoing elective hip surgery found no difference (N=430, 

15.1% vs. 16.5%, p=0.69).46 The study using olanzapine also found a decrease in delirium 

severity (DRS-R-98 score of 16.4 (SD 3.7) vs. 14.5 (SD 2.7), p=0.002) and duration (2.2 days 

(SD 1.3) vs. 1.6 (SD 0.7), p=0.02) in the treatment group;38 these outcomes were not reported in 

the study using risperidone44 or in one of the haloperidol studies50 The second haloperidol study 

reported significant decreases in severity and duration of delirium (both p<0.01) and a difference 

in length of stay for patient who developed delirium (11.1 days vs. 16.7 days, p<0.001)46

Of the three studies evaluating analgesia, two studies found enhanced pain prophylaxis decreased 

delirium incidence. One studied used a fascia iliaca compartment block (injection of local 

anesthesia beneath the fascial layer of the iliopsoas muscle as an approach to reaching the 

nerves of the lumbar plexus) vs. placebo before and after hip fracture surgery (N=219, 10.8% 
19

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

vs. 23.8%, p=0.02).43 The other study, a retrospective comparison of patients who received 

patient-controlled femoral nerve analgesia vs. intravenous analgesia following hip fracture 

surgery (N=99, 8.2% vs. 42.0%, p<0.001).53 A third study did not find a difference in delirium 

incidence between intervention subjects using continuous epidural bupivicaine and fentanyl 

vs. control subjects using continuous IV fentanyl for pain following bilateral knee replacement 

(N=51, 38.4% vs. 44.0%, p=0.69).13 The study using the fascia iliaca compartment block43 found 

significant differences in delirium severity (DRS-R-98 score of 14.3 (SD 3.6) vs. 18.6 (3.4), 

p<0.001) and duration (5.2 days (SD 4.3) vs. 11.0 days (SD 7.2), p<0.001) favoring the treatment 

intervention. The study using the patient-controlled femoral nerve analgesia53 found a significant 

difference in use of opioid rescue medications favoring the intervention group (0% vs. 28%, 

p<0.001). 

Other pharmacologic agents studied include melatonin, bendodiazipines, other post-operative 

sedatives, and anti-lipids. A recent study of melatonin prior to sleep in patients on the internal 

medicine wards found a decreased incidence of delirium compared to patients receiving placebo 

(N=122, 11.5% vs. 31.1%, p=0.01).37 Post-operative sedation with dexmedetomidine compared 

to either propofol or midazolam following cardiac valve surgery (with cardiopulmonary bypass) 

resulted in a decreased incidence of delirium (N=76, dexmedetomidine 10.0%, propofol 

44.4%, midazolam 42.5%, p<0.001 dexmedetomidine vs. both controls).42 There were also no 

differences in delirium duration, length of stay, or use of rescue medications.42 A study of a 

delirium-free protocol (diazepam, flunitrazepam, and pethidine) vs. usual care in patients who 

underwent resection of gastric or colorectal cancer found no difference in the incidence of 

delirium (N=40, 5.0% vs. 35.0%, p=0.06).49 Length of stay also did not differ. A non-randomized 

study found that administration of anti-lipid therapy did not alter the development of delirium 

between intervention and control subjects following cardiac surgery (N=1059, 10.8% vs.12.8%, 

p=0.33).52

Pooled Comparisons (Figure 5) 

We were able to pool randomized trials of antipsychotics versus placebo studies and 

cholinesterase inhibitors versus placebo for analysis; the other pharmacologic trials were 

too heterogeneous to allow for meta-analysis. In three small trials of cholinesterase inhibitor 

medications versus placebo (combined n = 226),40,45,47 prophylactic cholinesterase inhibitors 

(donepezil and rivastigimine) did not significantly decrease the development of delirium in older 

hospitalized patients (RR 0.93, 95%CI 0.51-1.69, I2=29%). 

In two trials of atypical antipsychotic medication versus placebo involving 526 individuals,38,44

prophylactic medications significantly decreased the development of delirium in older 

hospitalized patients (RR 0.35, 95%CI 0.25-0.50, I2=0%). 

Strength of Evidence (Table 3)

We evaluated the strength of evidence for the randomized studies of pharmacologic interventions 

using the approach described in the Methods section. Strength of evidence was low for all of the 

interventions that included only one randomized trial. Study quality, reflecting risk of bias, was 

rated as fair for all but one of the studies. Imprecision was noted for five of the studies. With one 

trial, it was not possible to assess consistency of the intervention effect.
20

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

For the two comparisons with multiple trials, one was rated low (acetylcholinesterase inhibitors 

versus placebo) while one was rated moderate (atypical antipsychotic agents versus placebo). 

Overall study quality was fair for both interventions but precision and consistency were noted for 

the atypical antipsychotic trials.

Figure 5. Incidence of Delirium, Randomized Pharmacologic Trials 

A. Acetylcholinesterase inhibitors versus placebo

Study or Subgroup

1.1.1 Donepezil versus placebo

Liptzin 2005

Sampson 2007

Subtotal (95% CI)

Total events

Heterogeneity: Tau2 = 0.59; Chi2 = 2.50, df = 1 (P = 0.11); I2 = 60%

Test for overall effect: Z = 0.57 (P = 0.57)

1.1.2 Rivastigimine versus placebo

Gamberini 2009

Subtotal (95% CI)

Total events

Heterogeneity: Not applicable

Test for overall effect: Z = 0.27 (P = 0.79)

Total (95% CI)

Total events

Heterogeneity: Tau2 = 0.09; Chi2 = 2.83, df = 2 (P = 0.24); I2 = 29%

Test for overall effect: Z = 0.24 (P = 0.81)

Test for subgroup differences: Chi2 = 0.39, df = 1 (P = 0.53), I2 = 0%

Events

8

2

10

18

18

28

Total

39

19

58

56

56

114

Events

7

5

12

17

17

29

Total

41

14

55

57

57

112

Weight

30.4%

14.0%

44.5%

55.5%

55.5%

100.0%

M-H, Random, 95% CI

1.20 [0.48, 3.00]

0.29 [0.07, 1.30]

0.68 [0.17, 2.62]

1.08 [0.62, 1.87]

1.08 [0.62, 1.87]

0.93 [0.51, 1.69]

Pharmacologic Placebo Risk Ratio Risk Ratio

M-H, Random, 95% CI

0.1 0.2 0.5 1 2 5 10

Favors pharmacologic Favors control

B. Atypical antipsychotic agents versus placebo

Study or Subgroup

1.5.2 Olanzapine (atypical antipsychotic) versus placebo: Orthopedic patients

Larsen 2010

Subtotal (95% CI)

Total events

Heterogeneity: Not applicable

Test for overall effect: Z = 5.31 (P < 0.00001)

1.5.3 Risperidone (atypical antipsychotic) versus placebo: Cardiac surgery patients

Prakanrattana 2007

Subtotal (95% CI)

Total events

Heterogeneity: Not applicable

Test for overall effect: Z = 2.62 (P = 0.009)

Total (95% CI)

Total events

Heterogeneity: Tau2 = 0.00; Chi2 = 0.00, df = 1 (P = 0.97); I2 = 0%

Test for overall effect: Z = 5.92 (P < 0.00001)

Test for subgroup differences: Chi2 = 0.00, df = 1 (P = 0.97), I2 = 0%

Events

28

28

7

7

35

Total

196

196

63

63

259

Events

82

82

20

20

102

Total

204

204

63

63

267

Weight

81.0%

81.0%

19.0%

19.0%

100.0%

M-H, Random, 95% CI

0.36 [0.24, 0.52]

0.36 [0.24, 0.52]

0.35 [0.16, 0.77]

0.35 [0.16, 0.77]

0.35 [0.25, 0.50]

Pharmacologic Placebo Risk Ratio Risk Ratio

M-H, Random, 95% CI

0.1 0.2 0.5 1 2 5 10

Favors pharmacologic Favors control
21

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

mmaries for the Randomized Pharmacologic Delirium Studies: Incidence of Delirium

Meta-analysis details;

notes Summary statistics Quality domains Evidence rating

hibitors 

007; 

3 trials

RR = 0.93 [95%CI 0.51 to 1.69]

Study quality: fair 

(n=226) Directness: direct Low

agents: donepezil (2) and 

rivastigimine

Imprecision: yesInconsistency: yes

agents 

ana 

2 trials

RR = 0.32 [95%CI 0.12 to 0.91]

Study quality: fair

(n=526) Directness: direct Moderate

agents: olanzapine and 

risperidone

Imprecision: noInconsistency: no

(with 

1 trial

RR = 0.91 [95%CI 0.59 to 1.42]

Study quality: good

(n=430) Directness: direct Low

proactive geriatric 

consultation for all patients

agent: haloperidol

Imprecision: yesInconsistency: NA

gents 

1 trial

RR = 0.32 [95%CI 0.12 to 0.91]

Study quality: fair

(n=78) Directness: direct Low

agent: haloperidol Imprecision: no

Inconsistency: NA

us 

1 trial

RR = 0.45 [95%CI 0.24 to 0.87]

Study quality: fair

(n=207) Directness: direct Low

Imprecision: noInconsistency: NA

rsus 

1 trial

RR = 0.87 [95%CI 0.45 to 1.69]

Study quality: fair

(n=51) Directness: direct Low

Imprecision: yesInconsistency: NA

ght 

1 trial

RR = 0.48 [95%CI 0.26 to 0.89]

Study quality: fair

(n=114) Directness: direct Low

agent: propofol Imprecision: no

Inconsistency: NA

placebo

1 trial

RR = 0.11 [95%CI 0.02 to 0.82]

Study quality: fair

(n=58) Directness: direct Low

administered during 

anesthetic induction 

Imprecision: noInconsistency: NA
22

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

Meta-analysis details;

notes Summary statistics Quality domains Evidence rating

sus 

1 trial RR = 0.74 [95%CI 0.21 to 2.59] Study quality: fair

(n=47) Directness: direct Low

regional was either 

epidural or spinal

Imprecision: yesInconsistency: NA

sus 

RR = 1.32 [95%CI 0.73 to 2.39]

Study quality: fair

Low (n=57) Directness: direct

Imprecision: yesInconsistency: NA

omidine

erative

1 trial

RR = 0.23 [95%CI 0.08 to 0.61]

Study quality: fair

(n=76) Directness: direct Low

Imprecision: noInconsistency: NA

omidine

erative

1 trial

RR = 0.24 [95%CI 0.09 to 0.64]

Study quality: fair

(n=80) Directness: direct Low

Imprecision: noInconsistency: NA

DFP) 

1 trial

RR = 0.14 [95%CI 0.02 to 1.06]

Study quality: fair

(n=40) Directness: direct Low

DFP: benzodiazepines and 

pethidine

Imprecision: yesInconsistency: NA

o

1 trial

RR = 0.37 [95%CI 0.17 to 0.81]

Study quality: fair

(n=122) Directness: direct Low

Imprecision: noInconsistency: NA

mized studies (Katznelson 2009, anti-lipid therapy;52 Del Rosario 2008, analgesia;53 Dautzenberg 2004 and Savage 1978, both 

tors12,54) should be considered at high-risk of bias due to lower study quality and therefore the summary of evidence is low.

A = not applicable; RR = relative risk 
23

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

Non-Pharmacologic or Mixed Studies

Nineteen studies, including 5 randomized, controlled trials and 14 non-randomized trials, 

evaluated non-pharmacologic or mixed methods of delirium prevention (Tables 4 and 5, 

Appendix D, Tables 3 and 4). Included patients tended to be at moderate-to-high risk for 

delirium, with patients recruited post-operatively, from ICUs or traumatological unit, or as 

geriatric internal medicine patients. The studies were widely variable in their interventions and 

reporting of outcomes. All reported on some measure of delirium incidence, 4 studies reported 

delirium severity, 7 studies reported delirium duration, 11 studies reported length of stay, and 

2 studies reported on the use of rescue medications). Of the 5 randomized trials, one assessed 

music therapy, one bright light therapy, one proactive geriatrics consultation and two involved 

staff education and varying multi-component interventions. 

Sixteen of the nineteen non-pharmacologic prevention studies examined multi-component 

interventions (see Table 4). Authors reported a significantly lower incidence of delirium in 

the intervention group in 2 of the 3 randomized trials and 10 of the 12 non-randomized trials 

(p<0.05) with one trial not reporting the significance level (Appendix D, Table 2). When relative 

risks were determined, all but one study found a reduced risk of delirium in the intervention; 

the difference was significant in 1 of the 3 randomized trials and 6 of the 12 non-randomized 

trials (Table 5). Relative risks in the 3 randomized trials ranged from 0.65 to 1.01; in the 12 

non-randomized trials, the range was 0.16 to 0.88. Of four multi-component studies reporting 

delirium severity, two reported that the intervention decreased severity.65,70 Three of seven studies 

reporting decreased delirium duration reported significantly better outcomes in the intervention 

group.55,70,71 Of eleven studies reporting length of stay, four found significantly shorter 

hospitalization for intervention patients with differences of 4 to 10 days.55,58,66,78 Both of the 

studies reporting on rescue medication use with found reductions among intervention patients,55,67

Three non-pharmacologic studies used a single intervention prevention strategy including 

randomized trials of bright light therapy56 and music57 and a non-randomized study of staff 

education alone.68 Using bright lights to enhance daytime awakening was not found to be 

an effective prevention strategy for delirium (N=15, 16.7% vs. 40.0%, p=0.42),56 however, 

playing largely instrumental, soothing music four times per day significantly decreased delirium 

incidence (N=126, 3.2% vs. 58.1%, p=0.001).57 A third study found that educating staff to 

increase delirium awareness and knowledge was effective in decreasing delirium incidence 

(N=250, 9.8% vs. 19.5%, p=0.03).68 None of these studies reported on other delirium outcomes.

Pooled Comparisons

The non-pharmacologic or mixed delirium prevention strategies could not be pooled due to the 

heterogeneity of the interventions tested. 

Strength of Evidence (Table 6)

We determined strength of evidence for the five randomized trials of non-pharmacologic 

interventions. One study was rated moderate due to the higher quality (lower risk of bias) of the 

study; the remaining four were rated low. Due to heterogeneity of the interventions, we did not 

rate the strength of evidence for the non-randomized trials.
24

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

ulti-Component Interventions for Delirium Prevention

MultiDisciplinary 

Team

Staff 

Education

Patient 

Assessment

Orientation 

and/or 

Sensory 

Impairment 

Training

Sleep Protocol

Early 

Mobilization

Environmental 

Modification

Medication 

Modification/

Pain 

Management

Nutrition/

Hydration

s

 bowel/bladder function, 

√ √ √ √ √ √ √

icine 

aff training) √ √ √ √

 

 function) √ √ √ √ √ √

√ √ √

√ √ √ √ √ √ √ √

√ √ √ √ √ √ √ √ √

64/renal √ √ √ √ √ √

√ √ √

discharge planning) √ √ √ √ √

√ √ √ √ √ √ √

edic 

oxygen) √ √ √ √ √ √ √

√ √ √

blications72-75/

√ √ √ √ √ √ √

√ √ √ √ √ √

e

egiver education) √ √ √ √ √ √

anesthetic technique) √ √
25

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

f Delirium - Non-Pharmacologic or Mixed Treatments Prevention Studies

Study Type/Patients Intervention

Control

Delirium Incidence/ 

Prevalence % (n/N)

Relative Risk [95% 

Confidence Interval]

RCT/orthopedic

Multi-factorial intervention 55 (56/102)Usual care 75 (73/97) 0.73 [0.59 to 0.90]

RCT/ICU

Bright light therapy 17 (1/6)Natural lighting environment 40 (2/5) 0.42 [0.05 to 3.36]

RCT/orthopedic

Music plus usual care 3 (2/62)Usual care 58 (36/62) 0.06 [0.01 to 0.22]

RCT/general medicine

Multi-component including education 32 (63/200)Usual care 31 (62/200) 1.01 [0.76 to 1.36]

RCT/orthopedic

Proactive geriatrics consultation 32 (20/62)Usual care 50 (32/64) 0.65 [0.42 to 1.00]

Non-randomized/neurology

Modified protocol 8 (3/38)Usual care 28 (23/81) 0.28 [0.09 to 0.87]

Non-randomized/geriatric medicine

Multi-disciplinary/component intervention 12 (20/170)Usual care 19 (69/372) 0.63 [0.40 to 1.01]

Non-randomized/renal

Delirium protocol 14 (11/80)Usual care 38 (30/80) 0.37 [0.20 to 0.68]

Non-randomized/geriatric

Multi-component intervention 6 (1/16)Usual care 38 (8/21) 0.16 [0.02 to 1.18]

Non-randomized/orthopedic

Proactive care of older people (POPS) 6 (3/54)Pre-POPS 19 (10/54) 0.30 [0.09 to 1.03]

Non-randomized/geriatric or general med

Multi-factorial intervention 23 (35/154)

Pre-intervention strategy 41 (45/110) 0.56 [0.38 to 0.80]

Non-randomized/geriatric or general med

Multi-factorial intervention 19 (21/110)

Pre-intervention strategy 41 (45/110) 0.47 [0.30 to 0.73]

Non-randomized/medicine

Educational package 10 (12/122)No educational package 20 (25/128) 0.50 [0.26 to 0.96]

9

Non-randomized/orthopedic

Quality improvement program 13 (9/71)No program group 36 (10/28) 0.35 [0.16 to 0.78]

Non-randomized/traumatological ward

Education of nursing staff 20 (12/60)Usual care 23 (14/60) 0.86 [0.46 to 1.45]

Non-randomized/general medicine

Multi-component strategy 10 (42/426)Matched controls 15 (64/426) 0.66 [0.46 to 0.95]

Non-randomized/orthopedic

Multi-component/education 31 (15/49)Usual care or medical intervention 55 (117/214) 0.56 [0.36 to 0.87]

Non-randomized/general medicine

Multi-component/education 19 (26/135)Usual care 22 (22/100) 0.88 [0.53 to 1.45]

Non-randomized/orthopedic

Surgical/anesthesia policy 48 (49/103)Pre-surgical/anesthesia policy 61 (68/111) 0.78 [0.60 to 1.00]

rolled trial
26

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

maries for the Randomized Non-pharmacologic Delirium Studies: Incidence of Delirium

Meta-analysis details;

notes Summary statistics Quality domains Evidence rating

on 

versus 

1 trial

RR = 0.73 [0.59 to 0.90]

Study quality: good

(n=199) Directness: direct Moderate

program elements included:

a) multi-disciplinary team; b) staff 

education; c) patient assessment;

d) sleep protocol; e) early mobilization; 

f) medication modification/pain 

management; g) nutrition/hydration

Imprecision: noInconsistency: NA

ntion 

1 trial

RR = 1.01 [0.76 to 1.36] 

Study quality: fair

(n=400) Directness: direct Low

program elements included:

a) staff education; b) patient assessment;

c) orientation and/or sensory impairment 

training; d) medication modification/

pain management

Imprecision: noInconsistency: NA

ntion 

sultation 

 24 hours 

 care

1 trial

RR = 0.65 [0.42 to 1.00]

Study quality: fair

(n=126) Directness: direct Low

program elements included:

a) patient assessment; b) orientation and/or 

sensory impairment training;

c) early mobilization; d) environmental 

modification; f) nutrition/hydration

Imprecision: yesInconsistency: NA

us Natural 

1 trial

RR = 0.42 [0.05 to 3.36]

Study quality: fair-poor

Low (n=15) Directness: direct

patients undergoing surgery for esophageal 

cancer

Imprecision: yesInconsistency: NA

e plus 

-operative 

1 trial

RR = 0.06 [0.01 to 0.22]

Study quality: fair-poor

(n=126) Directness: direct Low

patient’s choice from CDs provided Imprecision: no

Inconsistency: NA

ized studies should be considered at high-risk of bias due to lower study quality and therefore the summary of evidence is low.

U = intensive care unit; NA = not applicable; RR = relative risk
27

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

Harms

Mortality and adverse event data are reported on Table 7. Only trials reporting adverse event or 

mortality data are listed. Due to incomplete reporting and widely varying level of detail among 

studies that did report, it is difficult to determine whether one type of intervention was more 

likely to result in adverse events or deaths. 

Mortality

Seven studies of pharmacological interventions and eleven studies of non-pharmacological 

interventions report mortality data. Only one study, using a multi-component intervention, 

reported a difference in mortality between intervention and control groups. For patients who 

developed delirium, a lower mortality rate was found in the intervention group versus the 

control group (2 deaths in 63 intervention subjects ([3.2%] versus 9 deaths in 62 control subjects 

[14.5%], p=0.03).58

Adverse Events

Reporting of adverse events varied. Thirteen of twenty pharmacologic intervention studies 

and seven of nineteen non-pharmacologic intervention studies reported adverse event data. 

Overall, few differences between intervention and control groups were found. Among studies of 

pharmacologic interventions, the only significant adverse event related to use of restraints. One 

study of patients admitted to internal medicine units from the emergency department found that 

fewer patients treated with melatonin required restraints (6.6% vs. 9.8%, p=0.03).37 A second 

study, with patients who underwent elective total knee or total hip replacement surgery and 

received either olanzapine or placebo, found increased use of restraints in the intervention group 

(2.6% vs. 0%, p=0.03).38

Among studies of non-pharmacologic interventions, four studies reported significant differences 

in adverse events. One study, comparing a multi-factorial intervention to usual care in orthopedic 

patients, found fewer bed sores (9% vs. 22%) urinary tract infections (31% vs. 51%), nutritional 

complications (25% vs. 38%), and falls (12% vs. 27%) in the intervention group (all p<05).55

A second study, before and after implementation of a multidisciplinary program for patients 

undergoing elective orthopedic surgery, reported decreased uncontrolled pain (2% vs. 30%) and 

pressure sores (4% vs. 19%), and fewer patients with bedridden status (9% s. 28%) or unable 

to perform independent transfers on the third post-operative day (0% vs. 15%) (all p<0.05).66

Another pre-post study found fewer pressure sores (4% vs. 13%) and fewer severe falls (0% vs. 

5%) (both p<0.05) in patients undergoing surgery for hip fractures.78. Finally, implementation 

of a multi-component protocol in the medical-surgical unit was associated with a “statistically 

significant” reduction in restraint use.62
28

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

Mortality – Prevention Studies

Adverse Events n/N (%) Mortality n/N (%)

Intervention Control Intervention Control

n melatonin reported side effects 

e been secondary to the study 

related to delirium directly (1 patient 

mares and 1 patient reported feeling 

oating around and talking to his dead 

ntions

1 (6.6), p=0.03

endant services 2/57 (4 missing) 

Clinical interventionsRestraints 6/61 (9.8)Use of paid attendant services 1/60 (1 missing) (1.7)

6/61 (9.8), p=0.78Plus additional deaths from patients excluded from study analyses (n not reported)

8/61 (13.1)Plus additional deaths from patients excluded from study analyses (n not reported)

n 6/196 (3.1), p=NS

96 (1.0), p=NS

art failure 1/196 (0.5), p=NS

awal 5/196 (1.0), p=NS

196 (1.5), p=NS

fection 1/196 (0.5%), p=NSntions

6), p=NS

96 (2.6), p=0.03

96 (5.6), p=NS

Atrial fibrillation 3/204 (1.5)Arrhythmia 1/204 (0.5)Congestive heart failure 1 /204 (0.5)Alcohol withdrawal 1 /204 (0.5)Pneumonia 0/204(0)Urinary tract infection 4/204 (2.0)Clinical interventionsSitter 4/204 (2.0)Restraints 0/204 Bed alarm 7/204 (3.4)

omplication 30/57 (52.6), p=0.57

ostoperative complications 

r the entire population of each 

the following: urinary tract infection, 

 urinary drainage catheter, acute 

neumonia, congestive heart failure, 

arction, new dysrhythmia, fall, return 

monary embolus or deep venous 

 wound infection) 

S

Light sedationPatients ≥ 1 complication 26/57 (45.6)Patients with postoperative complications (averaged over the entire population of each group) 0.8 (1.4)

Deep sedationIntraoperative0/57, p>0.99During hospitalization2/57 (3.5), p>0.99

Light sedationIntraoperative0/57During hospitalization1/57 (1.8)
29

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

Adverse Events n/N (%) Mortality n/N (%)

Intervention Control Intervention Control

stroke 1/59 (1.7), p=1.0

 p=1.0

(67.8), p=0.1

9 (45.8), p=0.6

9 (66.1), p=1.0

(11.9), p=0.8

47.5), p=0.5

9 (55.9), p=0.1

n 22/59 (37.3), p=0.6

g arrhythmia 3/59 (5.1), p=1.0

 day 15/59 (25.4), p=0.12

Perioperative stroke 2/61 (3.3)Seizures 1/61 (1.6)Nausea 32/61 (52.5)Vomiting 24/61 (39.3)Anorexia 41/61 (67.2)Diarrhea 6/61 (9.8)Vertigo 24/61 (39.3)Insomnia 24/61 (39.3)Atrial fibrillation 26/61 (42.6)Life-threatening arrhythmia 3/61 (4.9)Pacemaker >1 day 24/61 (39.3)

1/59 (1.7), p=1.0 1/61 (1.6)

hypotension 2/40 (5.0) Midazolam group

Inoperative CVA 1/40 (2.5)

0/40 Dexmedetomidine 2/38 (5.3) Propofol

0/40 Midazolam

mas developed at the injection site 

d spontaneously”, p=NR

1/108 (0.9), p=NR 2/111

(1.8)

31.6), p=0.5

(15.8), p=0.5

(15.8), p=0.9

 (47.4), p=0.2

 (21.1), p=0.3

19 (5.3), p=0.8

3), p=0.8

1 AE 1/19 (5.3), p=0.42 AE 17/19 (89.5), p=0.4

Nausea 6/14 (42.9)Vomiting 1/14 (7.1)Diarrhea 2/19 (10.5)Insomnia 10/19 (52.6)Dizziness 1/14 (7.1)Paresthesia 1/14 (7.1)Fever 1/14 (7.1)Subjects with 1 AE 2/14 (14.3)Subjects with 2 AE 11/14 (78.6)

drew due to adverse events

d side effects were observed during 

3 subjects withdrew due to adverse events

complications 5/19 (26.3), p=NS Postoperative complications 8/28 (28.6)

ications 5/20 (25.0)

gy 8/20 (40.0)

Surgical complications 5/20 (25.0)

 not reported by treatment arm.

enia 20/51 (39.2)

ias 11/51 (21.6)

11/51 (21.6)

fections 3/51 (5.9)
30

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

Adverse Events n/N (%) Mortality n/N (%)

Intervention Control Intervention Control

28 (3.6)

bolism 2/28 (7.1) 2/28 (7.1)

28 (10.7)

nence 6/28 (21.4)

on 5/28 (17.9)

fection 9/28 (32.1)

8 (3.6)

r 3/28 (10.7)

0.7)

s p=NS

Pneumonia 2/29 (6.9)Depression 3/29 (10.3)Urinary incontinence 5/29 (17.2)Urinary retention 6/29 (20.7)Urinary tract infection 7/29 (24.1)Decubitus ulcer 5/29 (17.2)

One death on the first postoperative day. 3 additional deaths (group not defined) within 5 months post surgery

See intervention

 significant differences (p>0.05) in the transfusion index, hemoglobin level and rate 

toperative complications.

0/11, p>0.05 0/29

lization (significant differences vs. 

2 (8.8), p=0.01

fection 32/102 (31.4), p=0.01

mplications 25/102 (24.5), p=0.04

1.8), p=0.01

During hospitalization Bedsores 21/95 (22.1)Urinary tract infection 49/96 (51.0)Nutritional complications 37/97 (38.1)Falls 26/97 (26.8)

Over 12-month follow-up:16/102 (15.7), p=NS

Over 12-month follow-up:18/97 (18.6)

had to be reintubated (numbers not provided)

Delirium patients2/63 (3.2)p=0.03

Delirium patients9/62 (14.5)

10/170 (5.8)Delirium patients2/20 (10.0), p=0.60

19/372 (5.1)Delirium patients10/69 (14.5)

tation of acute confusion (AC) protocol

000 patient days: 

3.6 (in 2006); 4.2 (in 2007), p=NR

des per 1000 patient days: 1.3 (in 

2006); 0.09 (in 2007), reported to be 

gnificant”

Prior to implementation of AC protocol (2004)Fall rate per 1000 patient days: 4.8Restraint episodes per 1000 patient days: 8.7
31

, and Diagnosis – A Systematic Review of the Evidence Evidence-based Synthesis Program

Adverse Events n/N (%) Mortality n/N (%)

Intervention Control Intervention Control

0/16, p=NR 1/21 (4.8)

ain: 1/54 (1.9), p<0.01

4 days post-op: 0/54 

s: 2/54 (3.7), p=0.03

4 (9.3), p=0.01

nsfers on day 3 post-op: 0/54, 

Uncontrolled pain: 16/54 (29.6)No food for ≥ 4 days: 5/54 (9.3)Pressure sores: 10/54 (18.5)Bedridden: 15/54 (27.8)Dependent transfers on day 3 post-op: 8/54 (14.8)

0/54, p=NR 1/54 (1.9)

Baseline period2/28 (7.1), p=NR

Post-intervention3/71 (4.2)

Small number of deaths in the sampleOR for death in intervention cohort vs. non-intervention cohort: 3.86 (95%CI 0.09-1.71)6/426 (1.4)p=0.78

7/426 (1.6)

ms 

Severe fallsControl 1 6/111 (5.4)Control 2 0/103Eating problemsControl 1 8/111 (7.2)Control 2 5/103 (4.9)

In-hospital1/49 (2.0)p=0.81vs. C1,p=0.30 vs. C26-month8/49 (16.3)p=0.99 vs. C1,p=0.54 vs. C2

In-hospitalControl 13/111 (2.7)Control 26/103 (5.8)6-monthControl 118/111 (16.2)Control 213/103 (12.6)

 25/135 (19.0), p=NS

1 pre-defined events that developed 

Complications: 16/100 (16.0) Hospital mortality: 11/135 

(8), p=NS

Hospital mortality: 5/100 (5)

on: 33/103 (32.0), NS

rs: 4/103 (3.9), p<0.05

ems: 5/103 (4.9), NS

/103, p<0.05

Urinary infection: 26/111 (23.4)Decubital ulcers: 14/111 (12.6)Feeding problems: 8/111 (7.2)Severe falls: 6/111 (5.4)

Mortality rate was same in control and intervention studies

ficant but did not report p value; NR=not reported; AE=adverse event; CVA=cerebrovascular accident

emia, constipation, depression, diarrhea, heart failure, pneumonia, other infections, myocardial infarction, pulmonary embolism, stroke, stomach ulcers, and urinary 

as not significantly difference between intervention and control groups. 
32

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

QUESTION 2a: Do these results vary by medical unit, age, gender, or comorbid 

conditions?

None of the included studies were stratified by medical unit, age, or comorbid conditions. 

Likewise, none of the studies were stratified by gender, although two studies included only 

men.41,56 Therefore, we are unable to ascertain whether effectiveness varied by medical unit, age, 

gender or comorbid conditions.

Conclusions

Most of the included studies enrolled patients at high or very high risk of delirium as evidenced 

by incidence rates of delirium in the control group of 29-60%. The applicability of these findings 

to settings and patients with lower delirium risk is not clear. Low level evidence suggests that 

certain pharmacologic strategies in selected surgical settings may be useful. These include 

perioperative analgesia via fascia iliaca compartmental block for patients undergoing surgery 

for hip fracture, atypical antipsychotics, and lighter anesthesia. However, studies examining 

each category of prevention medications were small in size and number and inconsistencies in 

outcomes for various interventions occurred that are difficult to explain by patient population or 

setting (e.g. haloperidol was beneficial in patients undergoing gastrointestinal but not orthopedic 

surgery). Thus some findings could be due to chance or true effects could be missed due to 

small sample size and low event rates. There is low level evidence that use of cholinesterase 

inhibitors or perioperative statins do not reduce the risk of delirium. There is mixed evidence for 

continuous epidural bupivicaine plus fentanyl versus continuous IV fentanyl.

Multi-component strategies were generally successful in delirium prevention, although the 

interventions studied varied widely and often involved several strategies and disciplines. Thus 

it is difficult to determine the specific component(s) of effectiveness. Evidence suggests that 

staff education alone may be an effective strategy, as may be music therapy, although there 

are currently only two studies supporting these strategies. There is no evidence of a difference 

in delirium incidence associated with bright light therapy. Overall, the evidence suggests that 

there are few harms associated with the methods used in these studies for delirium prevention. 

However, it is difficult to determine the true extent of harms and whether they differ between 

pharmacologic and non-pharmacologic interventions due to incomplete reporting. None of the 

included studies were stratified by medical unit, age or comorbid conditions. Therefore, there 

are no data addressing whether the effectiveness or harms varies by medical unit, age, gender or 

comorbid conditions.
33

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

KEY QUESTION #3. What is the comparative diagnostic accuracy of 

the tools used to detect delirium:

a. In elderly medical and surgical inpatients?

b. In elderly ICU inpatients?

Elderly Medical and Surgical Inpatients

A recent systematic review addressed the accuracy of tools used to diagnose the presence of 

delirium in adults.79 We assessed the relevance of this review as recommended in the Agency 

for Healthcare Research and Quality Methods Guide.80 We found the review to be relevant - 

addressing the population, intervention, comparators, outcomes, timing, setting of interest for 

our review and including appropriate study designs. The exception was the exclusion of studies 

of delirium assessment for patients in an intensive care unit (ICU). We present those studies in 

Key Question 3b. We determined that the quality of the existing review was “good” based on the 

AMSTAR guidelines81

The review included citations from MEDLINE (1950 to May 2010), EMBASE (1980 to May 

2010), and a hand-search of bibliographies of relevant articles. The review was limited to studies 

that included hospitalized patients (not in the ICU), used an appropriate reference standard 

(especially DSM-III, DSM-III-R, or DSM-IV) performed by a specialist physician, applied 

the same index test to more than 80% of the patients, and included patients with and without 

delirium. Studies that enrolled primarily children or patients with alcohol-related delirium were 

excluded as were studies where the same individual performed both the index and reference tests. 

Study quality was assessed using the method described in the Rationale Clinical Examination 

series as described in the Methods section.8

The review included 25 studies enrolling between 26 and 791 patients.82-106 Although the review 

was not limited to studies of elderly patients, 15 of the 25 studies enrolled either patients older 

than 60 years or patients from geriatric units. In the 25 studies, 11 different diagnostic tools were 

used. The quality of 1 study was rated Level 1,97 7 were rated Level 2,82,85,94,96,98-100 9 were rated 

Level 3,83,84,86,89,90,91,93,95,101 and 8 were rated Level 4.87,88,92,95,103-106

In nine studies that consecutively enrolled patients the prevalence of delirium ranged from 9% 

to 63%,82,85,88,92,94,96,97,99,106 however only one study, which enrolled cancer patients consecutively 

referred for neurological or psychiatric consultation for mental status change, reported 

prevalence above 50%.97 Five of the nine studies enrolled patients older than age 60 or from 

geriatric units.82,85,88,92,96 Delirium prevalence in those studies ranged from 9% to 49%.

The most widely studied tool was the Confusion Assessment Method (CAM) with data reported 

from 12 studies that enrolled a total of 1036 patients82-88,98-100,102. CAM was developed to be 

administered by nonpsychiatric clinicians, is based on the 4 cardinal features of delirium, and 

takes approximately 5 minutes to administer.84 There were no studies with Level of Evidence 

1, 5 with Level of Evidence 2, 5 with Level of Evidence 3, and 2 with Level of Evidence 4. 

Sensitivity ranged from 13% to 98% with all but 2 studies greater than 75%. Specificity ranged 

from 77 to 100%. The pooled sensitivity was 86% and the pooled specificity was 93%. Positive 

test results were associated with a likelihood ratio that ranged from 4.1 to 167. The pooled 

likelihood ratio for a positive test was 9.6 (95%CI 5.8 to 16.0). Negative test results were 
34

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

associated with a likelihood ratio that ranged from 0.03 to 0.85. The pooled likelihood ratio for 

a negative test was 0.16 (95%CI 0.09 to 0.29). There was considerable heterogeneity in the 12 

studies as reflected in I2

 values of 65% for a positive test and 85% for a negative test. In 7 studies 

that enrolled either patients whose age was greater than 60 years or who were identified from 

geriatric units, sensitivity ranged from 46% to 95% and specificity ranged from 77% to 99%. 

Positive likelihood ratios ranged from 4.1 to 167; negative likelihood ratios ranged from 0.05 to 

0.59.

Four studies evaluated the Delirium Rating Scale (DRS), a 10-item observational scale 

developed to be used by clinicians with psychiatric training, and based on characteristic 

symptoms of delirium.91-93,97 The studies used a value of 10 or greater (on a scale of 0 to 32) 

to reflect a positive test. Total enrollment in these studies was 943. The pooled sensitivity 

was 95% and the pooled specificity was 79%. The pooled positive and negative likelihood 

ratios were 4.3 (95%CI 2.1 to 9.1) and 0.07 (95%CI 0.03 to 0.37), respectively. Heterogeneity 

associated with the likelihood ratios was low (I2

 values of 14% and 0%, respectively). Three 

of the studies enrolled patients from geriatric units. Two studies used a revised version of the 

DRS, the DRS-R-98 (total enrollment of 129). A positive test in these studies was indicated by 

a score greater than 20. One of the two studies enrolled patients 65 years and older. The pooled 

sensitivity was 93%; pooled specificity was 89%. The positive likelihood ratio was 8.0 (95%CI 

2.6 to 25, I2

 = 73%) and the negative likelihood ratio was 0.08 (95%CI 0.3 to 0.24, I2 = 0%). 

The Memorial Delirium Assessment Scale (MDAS), a 10-item clinician evaluation based on 

DSM criteria and requiring approximately 10 minutes to complete, was evaluated in 3 studies 

(a total of 330 patients).95,101,106 One of the studies enrolled patients from a geriatric unit. A score 

of 10 or greater indicated a positive test. Pooled sensitivity and specificity were both 92%. The 

pooled positive likelihood ratio was 12 (95%CI 2.4 to 5.8, I2

 = 85%) and the pooled negative 

likelihood ratio was 0.9 (95%CI 0.3 to 0.38, I2 = 69%). 

Two studies reported results from assessment of the 13 item Delirium Observation Screening 

Scale (DOSS), a tool designed for nurses and intended to identify early symptoms of delirium 

as part of regular care.89,90 The total enrollment was 178; all patients were 70 years and older. 

Pooled sensitivity was 92%; pooled specificity was 82%. The positive likelihood ratio was 5.2 

(95%CI 2.7 to 9.9, I2 =65%); the negative likelihood ratio was 0.10 (95%CI 0.03 to 0.37; I2 = 

0%).

Other tools identified in the review included the Clinical Assessment of Confusion (CAC), the 

Digit Span Test, the Global Attentiveness Rating (GAR), the Mini-Mental State Examination 

(MMSE), the Nursing Delirium Screening Scale (Nu-DESC), and the Vigilance “A” Test. Data 

were only reported from one study for each of these tools. 

The study authors identified other factors that might influence the choice of a diagnostic test. A 

tool that can be completed in 5 minutes or less or completed by someone other than a specialist 

physician might be required in certain conditions. 

Apart from studies examining the DRS, heterogeneity, as indicated by the I2

 values, was high. 

The authors explored the sources of heterogeneity in the studies that used the CAM. The I2

associated with the negative likelihood ratio decreased from 85% to 0% when the analysis only 
35

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

included studies where the index text was performed by a physician. The negative likelihood 

ratio increased only slightly (from 0.16 to 0.19). The positive likelihood ratio increased from 9.6 

to 19 but the I2

 also increased slightly (from 65% to 67%). The I2 associated with the negative 

likelihood ratio also decreased to 0% when only the higher quality studies (all Level of Evidence 

2) were used but the likelihood ratio again increased only slightly (from 0.16 to 0.20). The 

effects on the positive likelihood ratio and associated I2 value were not reported. The authors 

had speculated that the version of the DSM criteria used in the study might have contributed to 

heterogeneity but subgroup analyses based on DSM criteria did not produce different results.

Only one of the studies included in the systematic review enrolled patients from a VA medical 

center82 The focus of the study was on medical-surgical inpatients, older than age 60, who were 

referred to a psychiatric consultation service (PCS) for evaluation or treatment of depressive 

symptoms. The investigator used the CAM to assess the referred patients for delirium. A PCS 

psychiatrist interviewed the patients and diagnosed delirium based on DSM-III-R criteria. Only 

patients with concordant diagnoses by the investigator and the psychiatrist were included in 

the analysis (n=67). Five patients were excluded because the diagnoses were not concordant. 

In two cases, the psychiatrist diagnosed delirium but the investigator did not. In three cases, 

the investigator diagnosed delirium but the psychiatrist did not. Of the 67 patients, 28 (41.8%) 

were diagnosed with delirium. Twenty-four of the referrals had neither delirium nor a depressive 

disorder. The referring providers for 23 of the 28 delirium cases were contacted. It was 

determined that only 3 of the providers considered delirium in the differential diagnosis.

The authors concluded that administration of the GAR, MDAS, CAM, DRS-R-98, CAC, and 

DOSS all produced positive results suggestive of delirium with likelihood ratios of greater than 

5.0. Similarly, normal test results that decreased the likelihood of delirium with a likelihood 

ratio of less than 0.2 were found in studies that used the GAR, MDAS, CAM, DRS-R-98, DRS, 

DOSS, Nu-DESC, and the MMSE. As noted above, some of the tools were only evaluated 

in one study and some studies did not focus on an elderly population. Overall, the authors 

recommended the use of the CAM for a time-efficient, bedside delirium assessment.

One eligible study was identified in our search of the literature published after the search dates 

specified in the systematic review.107 The Level of Evidence for this study is 3. Patients (n=116) 

admitted to the surgical, orthopedic, or gynecological ward of one hospital were evaluated. 

Only elective surgery cases were included. They excluded patients who were undergoing 

neurosurgical procedures, or who had a history of psychiatric or neurological illness, a previous 

cerebral insult, or a history of drug or alcohol abuse. They also excluded patients who were 

unable to communicate due to severe hearing loss or brain injury. Daily delirium assessments 

(from preoperative day to sixth day postoperative) were performed by trained research assistants 

supervised by a psychiatrist. All patients were tested independently with the CAM, the NuDESC, and the Delirium Detection Score (DDS). Diagnosis of delirium according to DSM-IV 

criteria was the reference. 

Of the 116 patients screened, complete data were available for 88. Although patients of any age 

were eligible for the study, the mean age of those with complete data was 65.5 years; 64.8% 

were male. Delirium was diagnosed (DSM-IV criteria) in 17 (19%). Incidence of delirium based 

on the other assessment tools was as follows: CAM 17%, Nu-DESC 32%, and DDS 45%. The 
36

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

analysis of sensitivity and specificity was based on patient days. There were a total of 512 

patient days and 40 (8%) were identified as delirium according to DSM-IV criteria. With a 

cut-off point of 1 (greater than 1 indicating delirium), the sensitivity of the DDS was 71.2% 

(correct classification of 30 of the 40 patient days) and the sensitivity of the Nu-DESC was 

97.7% (correct classification of 38 of 40 patient days). The overall sensitivity of the CAM 

was 74.9% (correct classification of 28 of 40 patient days). The CAM was the most specific 

(100%), followed by the Nu-DESC (92.3%), and the DDS (87.1%). The positive likelihood 

ratios for the CAM, Nu-DESC, and DDS were all greater than 5 while the negative likelihood 

ratios were all 0.33 or less. 

Elderly ICU Inpatients

Instruments to detect delirium in critically ill patients, including those in the ICU, are a more 

recent development.108 We identified fifteen studies, enrolling between 22 and 178 subjects, 

that met inclusion criteria, reporting the diagnostic accuracy of a screening/assessment tool for 

detection of delirium in the ICU.109-123 Details of the studies are reported in Appendix D, Table 5.

Description of Studies

Patient Characteristics

Sample sizes ranged from 15 to 178. None of the studies reported specifically enrolling 

veterans. All fifteen studies reported gender, with men comprising the majority of the subjects 

(36 to 80%). For the thirteen studies reporting age,109-116,118-122 the mean age ranged from 55 to 

78 years. Five studies reported racial or ethnic characteristics.109-111,115,116 Overall, the majority 

of the subjects in these six studies were Caucasian (50% to 88%). Six of the studies included 

only medical patients, six included both medical and surgical patients, one included only 

surgical patients, and one included only patients undergoing psychiatric care. Four of the 

studies included patients who were intubated;110,112,113,118 the remainder of the studies included 

only patients who were not intubated. Five studies reported average ICU length of stay with 

values ranging from 6.0 to 9.2 days.111,116,117,120,121

Quality Assessment

Study quality was assessed using the method described in the Rationale Clinical Examination 

series as described in the Methods section.8

 Three studies were rated Level of Evidence 1,112,113,122

four were Level 2,114-116,123 two were Level 3,110,111 one was Level 4,109 and five were Level 5.117-121

Index and Reference Tools

In the 15 studies that met criteria, several different tools were used to identify the presence 

of delirium; some studies used more than one tool as the index test. The index tools studied 

included Confusion Assessment Method-Intensive Care Unit (CAM-ICU),110,112,113,115,116,122

Intensive Care Delirium Screening Checklist (ICDSC),114,117,122 Neelon and Champagne 

Confusion Scale (NEECHAM),120 Delirium Detection Score (DDS),112 CAM-ICU Flow 

sheet,123 Cognitive Test for Delirium (CTD),109 Nursing Delirium Screening Scale (NuDESC),112 Memorial Delirium Assessment Scale (MDAS),118 chart-based delirium method,111

clinical judgment,122 and observation checklist.119 The index test was administered by 

physicians, ICU nurses, nurse researchers, trained researchers, or psychology technicians.
37

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

The reference (or “gold standard”) diagnosis was determined by a psychiatrist using DSM 

III-R or DSM IV criteria in seven studies.109,110,112,113,116,122,123 Another study used the DSM III-R 

criteria but did not report who did the assessment119 and one study reported that the reference 

assessment was completed by a board certified psychiatrist but did not indicate which tool was 

used.114 One study used the International Classification of Disease system (ICD-10), with the 

assessment by a psychiatrist, to define delirium.118 In one study, the CAM, administered by 

a trained clinician researcher, was the reference test115 while in three studies, the CAM-ICU, 

administered by a research nurse, was used to determine the reference diagnosis.111.120.121 One 

study was a comparison of level of agreement between the ICDSC and the CAM ICU.117

Sensitivity and Specificity (Table 8)

The incidence of ICU delirium in the 13 studies that reported incidence ranged from 13% to 

87%. It should be noted that some studies did not enroll patients consecutively. For studies using 

the CAM ICU and reporting sensitivity and specificity data,110,112,113,115,116,122 sensitivity ranged 

from 64% to 100% and specificity ranged from 88% to 100%. One study developed a CAM-ICU 

Flowsheet.123 Sensitivity and specificity averaged 90% and 100%, respectively, for two different 

evaluators. Sensitivity and specificity were also reported for the ICDSC (2 studies) and the NuDESC, DDS, CTC, MDAS, and NEECHAM (1 study each).

Other Outcomes (Table 8)

Several studies reported outcome data for patients with and without delirium. Mortality was 

higher for patients with delirium.112,13,121 In one study, patients with delirium were less likely to be 

discharged to their home.112 Length of stay in the ICU was higher for patients with delirium.121,121

Conclusions

A systematic review of bedside instruments concluded that the CAM was a suitable tool for 

medical and surgical inpatients, including patients in geriatric units. The conclusion was based 

on sensitivity, specificity, likelihood ratios and feasibility of administration. Training on use 

of the CAM is recommended and the tool was designed to be used during a formal cognitive 

assessment. Fewer studies have evaluated the diagnostic accuracy of tools to detect delirium 

for elderly ICU inpatients. The CAM-ICU, a version of the CAM adapted for use in the ICU, 

appears to have high specificity but sensitivity varies (ranging from 64 to 100%) indicating that 

some patients with delirium will not be identified using the CAM-ICU alone. Not all of these 

studies were restricted to elderly patients and most excluded patients with neurological disease or 

cognitive dysfunction. Other tools have been evaluated in only one or two studies. 
38

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

Table 8. Outcomes – Intensive Care Unit Diagnostic Accuracy Studies

Author, Year

Screening Tool

Delirium Incidence

n/N (%)

Sensitivity

(%)

Specificity

(%)

Other Outcomes

Bergeron, 2001114

ICDSC with cut-off score 

of 4

15 of 93 (16%)

consecutive patients

99 64

Ely, 2001110

CAM-ICU

33 of 38 enrolled 

(87%) 

Nurse 1: 95

Nurse 2: 96

Intensivist: 100

Nurse 1: 93

Nurse 2: 93

Intensivist: 89

Likelihood Ratio (+): 

Nurse 1: 14; Nurse 2: 14; 

Intensivist: 9 

Accuracy 95%, 95%, 96%

Ely, 2001116

CAM ICU

80 of 96 (83%)

consecutive patients

Nurse 1: 100

Nurse 2: 93

Nurse 1: 98

Nurse 2: 100

Likelihood ratios: Nurse 1 

50, Nurse 2 >100

LOS 17.9 days (mean) ICU 

LOS 8.3 days (mean)

In hospital mortality 30.2%

Guenther, 2010123

CAM-ICU Flowsheet

25 of 54 enrolled 

(46%)

Intensivist: 88

Medical 

Student: 92

Intensivist: 100

Medical 

Student: 100

Hart, 1996109

CTD with cut-off score <19

Not applicable 100 95

Koolhoven, 1996119

Observational checklist

2 of 15 enrolled (13%) NR NR The 2 patients with delirium 

had scores >10 on DRS; 

2 other patients had DRS 

scores >10 but symptoms 

did not persist so not 

diagnosed

Lin, 2004113

CAM-ICU

22/102 (22%)

consecutive patients

Assessor 1:91

Assessor 2: 98

Assessor 1: 95

Assessor 2: 98

Likelihood Ratio: 45.5 

(Assessor 1,), 47.5 

(Assessor 2)

Mortality: 33% in no delirium 

group, 64% in delirium 

group

Luetz, 2010112

CAM-ICU

Nu-DESC

DDS

63/156 (40%)

consecutive patients

CAM-ICU: 81

Nu-DESC: 83

DDS: 30

(1st day)

CAM-ICU: 96

Nu-DESC: 81

DDS: 91

(1st day)

Mortality: 4% in no-delirium 

group, 24% in delirium 

group

Discharge to home 55% in 

no-delirium group, 24% in 

delirium group

McNicoll, 2005115

CAM ICU

11 of 22 (50%) 

consecutive patients

73 100

Pisani, 2006111

Chart-based delirium 

detection method

143 of 178 enrolled 

(80%) 

64 85 All patients: 

ICU LOS: 8.2 days (mean); 

5.0 days (median)

Plaschke, 2008117

CAM-ICU and ICDSC

71 of 174 enrolled 

(41%)

N/A N/A Kappa coefficient .80 (CI 

95%: 0.76-0.85)

ICU LOS: 9.2 days (mean)

Hospital LOS: 24.0 days 

(mean)

In-hospital mortality: 19%

Shyamsundar, 2009118

MDAS with cut-off score 

of 10 (unclear how many 

patients were assessed 

with reference test)

NR 100 96 
39

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

Author, Year

Screening Tool

Delirium Incidence

n/N (%)

Sensitivity

(%)

Specificity

(%)

Other Outcomes

Spronk, 2009121

Clinical judgment

23 of 46 enrolled 

(50%)

Physicians: 28

Nurses 35

(for days with 

delirium)

Physicians: 

100

Nurses: 98.3

(for days with 

delirium)

ICU LOS: 6 days (9 days 

for patients with delirium, 

5 days for patients without 

delirium)

Mortality: 24% (26% with 

delirium, 22% without)

van Eijk, 2009122

CAM-ICU, 

ICDSC, diagnostic 

impression of clinician

43 of 126 enrolled 

(34%)

CAM-ICU: 64

ICDSC: 43

Clinician 

impression: 29

CAM-ICU: 88

ICDSC: 95

Clinician 

impression: 96

van Rompaey, 2007120

NEECHAM with cut-off 

score of <20 

35 of 172 (20.3%) 

consecutive patients 

with NEECHAM, 34 

of 172 (19.8%) with 

CAM-ICU

87 95 ICU LOS 7.0 (mean) 

(17.5 days for patients 

with delirium, 5.0 days for 

patients without delirium)

ICU = intensive care unit; LOS = length of stay; N/A = not applicable; NR = not reported

CAM-ICU = Confusion Assessment Method – Intensive Care Unit; CAM = Confusion Assessment Method; CTD = 

Cognitive Test for Delirium; DDS = Delirium Detection Score; DSM = Diagnostic and Statistical Manual of Mental 

Disorders; ICDSC = Intensive Care Delirium Screening Checklist; MDAS = Memorial Delirium Assessment Scale; 

NEECHAM = Neelon and Champagne Confusion Scale; Nu-DESC: Nursing Delirium Screening Scale
40

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

SUMMARY AND DISCUSSION

SUMMARY OF EVIDENCE BY KEY QUESTION

Key Question #1. What is the effectiveness of screening for delirium in adult 

inpatients? 

1a. Do these results vary by medical unit, age, gender or comorbid conditions? 

1b. Does screening for delirium improve clinical outcomes?

We identified no randomized controlled trials of screening for delirium in hospitalized patients. 

There is no direct evidence that screening for delirium is beneficial or harmful. However, 

universal screening may pose harms, such as misclassification, subsequent treatment of nondelirious patients or misdiagnosis of those with delirium. Opportunity costs include the time 

to administer screening tests and follow-up (including those of the consultants-typically a 

psychiatric consult) required for positive results. Additionally, we found no evidence from recent 

systematic reviews that pharmacologic and non-pharmacologic delirium treatments improve 

outcomes. Therefore, we conclude that the evidence is insufficient about the net benefit of 

delirium screening among all hospitalized patients or subgroups of patients as defined by age, 

gender, comorbidities or admission to intensive care units. 

Key Question #2. What are the effectiveness and harms of delirium prevention 

strategies in acute elderly inpatients? 

2a. Do these results vary by medical unit, age, gender or comorbid conditions?

Low level evidence suggests that pharmacologic strategies using analgesia via fascia iliaca 

compartmental block, antipsychotics, and lighter anesthesia may be useful in delirium 

prevention. However, there were only a few studies, small in size, examining each category of 

prevention medications, and more research is needed. Pre-operative administration of statins 

was not found to effect the incidence of delirium. The evidence for peri-operative use of 

cholinesterase inhibitors and continuous epidural bupivicaine plus fentanyl versus continuous 

intravenous fentanyl is mixed. 

The evidence shows that multi-component strategies were generally successful in delirium 

prevention, although these interventions varied widely and often involved multiple strategies 

and disciplines, making it difficult to determine which components of the multi-component 

strategies may be effective. The evidence suggests that staff education alone or music therapy 

may be effective strategies, although there are currently only two studies supporting these 

interventions. There is no evidence that bright light therapy is an effective strategy for delirium 

prevention. 

The evidence suggests that there are few harms associated with the methods used in these 

studies for delirium prevention. None of the included studies were stratified by medical unit, 

age or comorbid conditions. Therefore, we are unable to ascertain whether effectiveness or 

harms varied by medical unit, age, gender or comorbid conditions.
41

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

KEY QUESTION #3. What is the comparative diagnostic accuracy of the tools 

used to detect delirium:

3a. In elderly medical and surgical inpatients?

3b. In elderly ICU inpatients?

A systematic review of bedside instruments concluded that the CAM was a suitable tool for 

medical and surgical inpatients, many of whom were evaluated in geriatric units. The ease 

of administration (completion in less than 5 minutes) was also considered although it was 

noted that administrators should be trained for optimal use and that the CAM was originally 

developed for use in conjunction with a formal cognitive assessment. The accuracy of bedside 

instruments delivered by individuals without training as stand-alone tools for delirium screening 

is not known. Fewer studies have evaluated the diagnostic accuracy of tools to detect delirium 

for elderly ICU inpatients. The CAM-ICU, a version of the CAM adapted for use in the ICU, 

appears to have high specificity but sensitivity varies (ranging from 64 to 100%) indicating that 

some patients with delirium will not be identified using the CAM-ICU alone. Not all of these 

studies were restricted to elderly patients and most excluded patients with neurological disease or 

cognitive dysfunction. Other tools have been evaluated in only one or two studies. 

RECOMMENDATIONS FOR FUTURE RESEARCH

The highest future research need is to conduct a randomized trial to evaluate the effectiveness 

and harms of screening for delirium in adults admitted to hospitals. Enrollment could target 

individuals likely to be at increased risk for, and thus hopefully at greatest benefit of, 

successful screening, prevention and treatment options. These could include individuals who 

are elderly, those with multiple comorbid conditions including mental health and cognitive 

impairment, and those receiving or likely to receive interventions or medications that can 

increase the risk of delirium and patients admitted to intensive care units. Additional work is 

needed to more clearly assess the harms associated with delirium screening and prevention, 

including the opportunity costs to health service personnel. These opportunity costs include 

the time and effort to administer screening tools as well as the downstream effects that 

occur based on follow-up of positive screen results or the efforts required for preventive 

strategies. More research is needed to verify the findings that some pharmacologic and nonpharmacologic strategies are helpful in the prevention of delirium, particularly in larger 

and more diverse populations, and with reports stratified by age, medical unit and comorbid 

conditions. Additionally, more research is needed to start to identify which components of the 

multi-component non-pharmacologic strategies may be most successful in delirium prevention. 

Investigations regarding delirium that may be provoked only by certain medication use (in the 

absence of other causes) would be very helpful; they may well have different prognoses than 

the multifactorial delirium. This research may offer some recommendations for prevention 

strategies that could easily be implemented. Finally, continued evaluation of diagnostic tools 

is warranted including the effects of training on diagnostic accuracy and the use of the tools in 

combination with other (e.g., cognitive) patient assessments.
42

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

CONCLUSIONS

Our review of the evidence on screening for and prevention and diagnosis of delirium finds the 

following:

1. There is insufficient evidence regarding benefits and harms of delirium screening 

in hospitalized patients including subgroups of patients as defined by age, gender, 

comorbidities, or ICU admission. We identified no randomized trials of screening for 

delirium in hospitalized patients. Conducting large pragmatic delirium screening trials is a 

high-priority research need.

2. There are low quality data regarding pharmacological strategies to prevent delirium. Many 

proactive preventive strategies have not been examined; those that have are typically reported 

in only a single trial. In addition, sample sizes are typically small, populations represent 

only selected groups of patients, and there is little consistency or completeness of outcomes 

reporting.

3. Multi-component interventions hold promise and are widely used in real world settings but 

few randomized trials have been reported. The absolute effectiveness and the contributing 

effectiveness of individual components is not well known but most appear to include some 

method of staff education to increase awareness of signs/symptoms and encourage reporting 

of delirium with subsequent earlier intervention.

4. Available diagnostic tests have acceptable diagnostic operating characteristics in the 

populations and settings where they have been studied and when administered by individuals 

with adequate training. Concurrent mental status testing may also be a factor in accuracy of 

diagnosis with these tests. It is not known whether the operating characteristics are robust 

across a wide range of populations and settings where the prevalence and incidence of 

delirium varied from the reported studies.

5. Additional research is needed to evaluate the clinical effectiveness and harms of screening, 

pharmacological and non-pharmacological interventions to prevent delirium applied to 

a larger and more diverse population, and diagnostic tools used in a broader range of 

populations and settings.
43

Delirium: Screening, Prevention, and Diagnosis – 

A Systematic Review of the Evidence Evidence-based Synthesis Program

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