Delirium Screening Scales Pounding Down the Home Stretch: The Delirium Observation Screening Scale and the Nursing Delirium Screening Scale Nose to Nose?

Today I’ve got an ambitious post because our Delirium Early Detection and Prevention Project committee has an ambitious project. Ever since the Neufeld Study, we’ve been scrambling to come up with an acceptable replacement for the Confusion Assessment Method-Intensive Care Unit (CAM-ICU) screen we were planning to use on our proposed general medical unit pilot unit. Recall the Neufeld study recently published a study showing the CAM-ICU has very low sensitivity as a screen for delirium in non-critically ill patients. See link . The authors of this very timely study (at least for us) also were less than enthusiastic about the original CAM for use by nurses as well, owing to the low sensitivity of the CAM if they are not well-trained in its use and fail to administer additional cognitive assessments.

We’re now considering comparing the Delirium Observation Screening Scale (DOS) and the Nursing Delirium Screening Scale (Nu-DESC). No doubt some of you who regularly read my Blog have noticed the results so far on the delirium screening scale poll, which shows a preference for the CAM, without any votes so far for the Nu-DESC as a stand-alone. There may be more enthusiasm for the Nu-DESC if combined with a test or task which assesses inattention. The DOS actually has two votes because one vote went to the “Other” option. The Single Question in Delirium (SQiD) also actually has a couple of tentacles, sorry, votes for the same reason. See the link
for the abstract about the SQiD, which essentially uses a collateral history gathering query, “Do you think [name of patient] has been more confused lately?”

And to reiterate, the CAM by itself used by untrained and very busy nurses is pretty insensitive. This begs the question of how it would perform if nurses consistently administered a brief cognitive assessment along with the CAM. Unfortunately, some late-breaking news reveals the Sweet 16 is not available right now. For reasons that remain unclear at this moment, Psychological Assessment Resources (PAR), Inc., requested that the instrument be removed from the Hospital Elder Life Program (HELP) website. I’ve contacted PAR for details and await a reply. The delirium screening scale poll has been updated accordingly.

The poll has many limitations, of course, including the very low response rate despite my solicitation to the memberships of the Academy of Psychosomatic Medicine (APM), the Nurses Improving Care for Healthsystem Elders (NICHE), and the International Society of Psychiatric-Mental Health Nurses (ISPN). However, to be fair, these large organizations have a lot of priorities on their respective agendas and in some cases there has simply not been time enough to respond to my invitation.

Below I’ve listed selected articles with abstracts about the DOS and the Nu-DESC as well as a couple of recent reviews about delirium rating scales generally for everyone’s review. No doubt many of you have your own reference lists as well.

Adamis et al has this to say about the DOS:

The Delirium Observation Screening (DOS) scale is a 25-item
scale based on DSM-IV criteria that was developed for screening for delirium by
nursing observations (Schuurmans, Shortridge-Baggett, & Duursma, 2003b). It
has acceptable predictive validity against the DSM-IV, good correlation with
the MMSE, and high internal consistency. The scale was subsequently shortened to
13 items and can be rated in less than five minutes (Schuurmans, Donders, Shortridge-Bagget,
& Duursma, 2002). A score of zero is defined as ‘normal behaviour’, meaning
the absence of behavioural alterations. The highest total score is 13 and the
cut-off point is 3. Three or more points indicate the presence of delirium. The
sensitivity of the scale was 0.89 and specificity was 0.88.

Wong et al identified both the Nu-DESC and the DOS as “time-efficient bedside” instruments that can be completed in 5 minutes or less. Excerpts follow:

The CAM: The CAM includes an instrument and diagnostic algorithm for identification of delirium. The instrument assesses the presence, severity, and fluctuation of 9 delirium features: acute onset, inattention, disorganized thinking, altered level of consciousness, disorientation, memory impairment, perceptual disturbances, psychomotor agitation or retardation, and altered sleep-wake cycle. The questionnaire can be administered in 5 minutes. The algorithm is based on the cardinal elements of the Diagnostic and Statistical Manual of Mental Disorders (DSM) (Third Edition, Revised) criteria for delirium: features 1 (acute onset and fluctuating course) and 2 (inattention) are essential features, and feature 3 (disorganized thinking) or 4 (altered level of consciousness) is supported by expert judgment and clinical practice, in which the first 2 and either of the latter 2 are required for diagnosis.

The DOS: The original version consisted of a 25-item scale based on the DSM-IV criteria for delirium. The scale was designed to capture early symptoms of delirium that nurses could observe during regular care. The scale was subsequently reduced to 13 observations that could each be rated as normal (score, 0) or abnormal (score, 1). A total score of 3 or more points indicates delirium. Completion of the instrument requires less than 5 minutes.

The Nu-DESC: A screening scale (range, 0-10) designed to be administered by a nurse based on clinical observation in routine practice. Five symptoms are rated: disorientation, inappropriate behavior, inappropriate communication, hallucination, and psychomotor retardation. The threshold for delirium is a score of 2 or more. On average, the instrument can be completed in 1 minute.

Wong et al clearly favored the CAM. Adamis et al also preferred the CAM as well as the NEECHAM and  two other scales which are not intended for nurses (the Memorial Delirium Assessment Scale and the Delirium Rating Scale).

The goal is to detect delirium early in order to prevent morbidity and mortality, especially in the elderly. It’s still not clear to me why there are no votes for the NEECHAM because the literature supports its utility in early detection of acute confusion. The primary psychometric validation reference for the  NEECHAM Confusion Scale is:

Neelon VJ, Champagne MT, Carlson JR et al. (1996). NEECHAM confusion scale: construction, validation, and clinical testing.  Nurs Res; 45:324-30.Abstract: This article reports the development of the NEECHAM Confusion Scale for rapid and unobtrusive assessment and monitoring of acute confusion. The scale was tested in two samples (N = 168 and 258, respectively) of elderly patients hospitalized for acute medical illness. Internal consistency and interrater reliability of the instrument were found to be high. The NEECHAM correlated well with the Mini-Mental State Examination and the sum of DSM-III-R positive items. Factor analyses identified and confirmed cognitive/behavioral and physiological domains. The NEECHAM provides a valid and reliable bedside assessment of acute confusion, particularly at its onset and in patients with”quiet” manifestations.

However, nurses clearly preferred the DOS in a head to head study with the NEECHAM. See link,

As I’ve said previously, I think we tend to underestimate the importance of the organizational culture into which we try to dip the delirium screening scales. Adamis et al summarized the role of a variety of factors which influence the choice of delirium screening instrument:

  • Purpose of the scale. Different scale properties are required depending on whether it is being used for clinical or research purposes. Certain scales are better screening instruments (e.g. the NEECHAM), some are more suited to making a diagnosis (e.g. the CAM), whilst others are good for measuring symptom severity (e.g. the DRS).
  • Clinical setting. Different settings require different scales. In this review, primary scales for elderly medical in-patients were reviewed, whereas ICU or alcohol treatment centers will require different scales.
  • Properties of the scale. General properties (e.g. administration time) and psychometric properties (e.g. validity, reliability) for the given population are pertinent to choice.
  • Popularity of the scale. Scales that are frequently used in other delirium studies permit inter-scale comparison.
  • Familiarity with the scale. The previous experience of the clinician or researcher will influence scale choice.
  • Organizational culture. Within various academic departments, hospitals or research teams there will be a preference towards using a certain scale based on need and the preference of influential individuals with the organization.

1. Adamis, D., N. Sharma, et al. (2010). “Delirium scales: A review of current evidence.” Aging Ment Health 14(5): 543-55.

OBJECTIVES: Delirium is a common neuropsychiatric condition with many adverse outcomes in elderly populations including death. Despite this, it is often misdiagnosed and
mistreated. A number of scales can be used to detect delirium. We review scales that have been used in delirium studies and report their psychometric properties. METHOD: An extensive MEDLINE database search and subsequent examination of reference lists was conducted to identify the various delirium scales that have been designed, primarily for use in the elderly. RESULTS: Twenty-four scales were identified. Delirium instruments differed according to the classification system they were based on, length of time to administer, the rater and whether they were screening scales or measured symptom severity. The psychometric properties of each scale is reported. CONCLUSION: A large number of scales exist, but not all are properly evaluated in terms of psychometric properties, and there is not unanimity about which scale is the best. However, a small number of scales may be considered already to be robust and useable: the CAM, the DRS, the MDAS and the NEECHAM.

2. Gemert van, L. and M. Schuurmans (2007). “The Neecham Confusion Scale and the Delirium Observation Screening Scale: Capacity to discriminate and ease of use in clinical practice.” BMC Nursing 6(1): 3.

BACKGROUND:Delirium is a frequent form of psychopathology in elderly hospitalized patients; it is a symptom of acute somatic illness. The consequences of delirium include high morbidity and mortality, lengthened hospital stay, and nursing home placement. Early recognition of delirium symptoms enables the underlying cause to be diagnosed and treated and can prevent negative outcomes. The aim of this study was to determine which of the two delirium observation screening scales, the NEECHAM Confusion Scale or the Delirium Observation Screening (DOS) scale, has the best discriminative capacity for diagnosing delirium and which is more practical for daily use by nurses.METHODS:The project was conducted on four wards of a university hospital; 87 patients were included. During 3 shifts, these patients were observed for symptoms of delirium, which were rated on both scales. A DSM-IV diagnosis of delirium was made or rejected by a geriatrician. Nurses were asked to rate the practical value of both scales using a structured questionnaire.RESULTS:The sensitivity (0.89 – 1.00) and specificity (0.86 – 0.88) of the DOS and the NEECHAM were high for both scales. Nurses rated the practical use of the DOS scale as significantly easier than the NEECHAM.CONCLUSION:Successful implementation of standardized observation depends largely on the consent of professionals and their acceptance of a scale. In our hospital, we therefore chose to involve nurses in the choice between two instruments. During the study they were able to experience both scales and give their opinion on ease of use. In the final decision on the instrument we found that both scales were very acceptable in terms of sensitivity and specificity, so the opinion of the nurses was decisive. They were positive about both instruments; however, they rated the DOS scale as significantly easier to use and relevant to their practice. Our findings were obtained from a single site study with a small sample, so a large comparative trial to study the value of both scales further is recommended. On the basis of our experience during this study and findings from the literature with regard to the implementation of delirium guidelines, we will monitor the further implementation of the DOS Scale in our hospital with intensive consultation.

3. Koster, S., A. G. Hensens, et al. (2009). “The delirium observation screening scale recognizes delirium early after cardiac surgery.” European Journal of Cardiovascular Nursing 8(4): 309-314.

BACKGROUND: Delirium or acute confusion is a temporary mental disorder which occurs frequently among hospitalized elderly patients. Patients who undergo cardiac surgery have an increased risk of developing delirium. Prevention or early recognition of delirium is essential. The Delirium Observation Screening (DOS) scale was developed to facilitate early recognition of delirium by nurses’ observations during routine clinical care.Aim The aim of this study was to validate the DOS scale in accordance with the diagnosis of the psychiatrist, using the DSM-IV criteria as the gold standard.Methods In this observational study, the DOS scale was used to assess whether 112 patients who underwent elective cardiac surgery had developed a postoperative delirium. The psychiatrist was consulted to confirm or refute the diagnosis delirium. Wilcoxon’s Rank Sum Test was utilized to compare patients with and without delirium on duration of hospital stay. A Receiver Operating Characteristic Curve of the DOS scale was constructed with accompanying Area Under the Curve (AUC).Results Based on the diagnosis of the psychiatrist, the incidence of delirium following cardiac surgery was 21.4% and the mean duration of delirium was two and a half days. The time to discharge was 11 days longer in patients with delirium. In 27 of the 112 patients a DOS score of > = 3 was found, that indicates delirium. The sensitivity and specificity of the DOS scale was 100% and 96.6% respectively. The AUC was 0.98.Conclusion The DOS scale is a very good instrument to facilitate early recognition of delirium by nurses’ observation of patients who undergo cardiac surgery. Early recognition will expedite good postoperative management such as implementation of appropriate interventions, and may decrease negative consequences caused by postoperative delirium.

4. Scheffer, A. C., B. C. van Munster, et al. (2011). “Assessing severity of delirium by the delirium observation screening scale.” International Journal of Geriatric Psychiatry 26(3): 284-291.

ABSTRACT: Objective: Delirium is the most common acute neuropsychiatric disorder in hospitalized elderly. Assessment of the severity of delirium is important for adjusting medication. The minimal dose of medication is preferable to prevent side effects. Only few nurse based severity measures are available. The aim of this study was to validate a scale developed to assess symptoms of delirium during regular nursing care, the Delirium Observation Screening (DOS) Scale, for monitoring severity of delirium. Method Delirious patients of 65 years and older were included. Delirium was diagnosed according to DSM-IV criteria and the Confusion Assessment Method. The DOS Scale was compared to the Dutch version of the Delirium Rating Scale-Revised-98 (DRS-R-98). Global cognitive functioning was assessed by the Informant Questionnaire Cognitive Decline in the Elderly Short Form (IQCODE-SF) and the KATZ-ADL Scale was used for functional impairment. Results Ninety seven delirious patients were included: 41 hip fracture patients and 56 medical patients. The correlation between total DRS-R-98 scores and DOS Scale scores was 0.67 (p = 0.01). For the cognitive impaired group (IQCODE-SF ≥3.9) this correlation was 0.61 (p = 0.01); for the group with no global cognitive impairment, this correlation was 0.67 (p = 0.01). Correlations between DRS-R-98 and DOS Scale for hypoactive, hyperactive and mixed delirium subtype were 0.40 (p = 0.32), 0.44 (p = 0.01) and 0.69 (p = 0.05), respectively. Conclusions The DOS Scale is able to measure severity of delirium. In routine daily clinical practice, the DOS Scale is a time-efficient, easy to use and reliable method for measuring and monitoring severity of delirium by nurses. Copyright © 2010 John Wiley & Sons, Ltd.

5. Schuurmans, M. J., L. M. Shortridge-Bagget, et al. (2003). “The Delirium Observation Screening Scale: a screening instrument for delirium.” Research & Theory for Nursing Practices 17: 31 – 50.

The Delirium Observation Screening (DOS) scale, a 25-item scale, was developed to facilitate early recognition of delirium, according to the Diagnostic and Statistical Manual-IV criteria, based on nurses’ observations during regular care. The scale was tested for content validity by a group of seven experts in the field of delirium. Internal consistency, predictive validity, and concurrent and construct validity were tested in two prospective studies with high risk groups of patients: geriatric medicine patients and elderly hip fracture patients. Among the patients admitted to a geriatric department (N = 82), 4 became delirious; among the elderly hip fracture patients (N = 92), 18 became delirious. The DOS scale was determined to be content valid and showed high internal consistency, alpha = 0.93 and alpha = 0.96. Predictive validity against the Diagnostic and Statistical Manual-IV diagnosis of delirium made by a geriatrician was good in both studies. Correlations of the DOS scale with the Mini Mental State Examination (MMSE) were Rs -0.79 (p < or = 0.001) in the hip fracture patients and Rs -0.66 (p < or = 0.001) in the geriatric medicine patients. Concurrent validity, as tested by comparison of the research nurse’s ratings of the DOS scale and the Confusion Assessment Method (CAM), for the group of hip fracture patients was 0.63 (p < or = 0.001). Construct validity of the DOS was tested against the Informant Questionnaire of Cognitive Decline in Elderly (IQCODE), a preexisting psychiatric diagnosis and the Barthel Index. Correlation with the IQCODE was 0.74 (p < or = 0.001) in the study with the hip fracture patients and 0.33 (p < or = 0.05) in the study with the geriatric medicine patients. Correlation with the Barthel Index was
-0.26 (p < or = 0.05) in the geriatric medicine patients and -0.55 (p < or = 0.001) in the hip fracture patients. The overall conclusion of these studies is that the DOS scale shows satisfactory validity and reliability, to guide early recognition of delirium by nurses’ observation.

6. Wong, C. L., J. Holroyd-Leduc, et al. (2010). “Does this patient have delirium?: value of bedside instruments.” JAMA 304(7): 779-86.

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

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