Delirium subtype identification and the validation of the delirium rating scale-revised-98 (dutch version) in hospitalized elderly patients

INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY Int. J. Geriatr Psychiatry 2006; 21: 876-882.
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/gps.1577 Delirium subtype identification and the validation of theDelirium Rating Scale-Revised-98 (Dutch version) inhospitalized elderly patients Sophia E. de Rooij1*, Barbara C. van Munster1,2, Johanna C. Korevaar2,Gerty Casteelen3, Marieke J. Schuurmans4, Roos C. van der Mast5 and Marcel Levi1 1Department of Internal Medicine and Geriatrics, Academic Medical Center, Amsterdam, The Netherlands2Department of Clinical Epidemiology and Biostatistics, Academic Medical Center, Amsterdam, The Netherlands3Department of Psychiatry, Academic Medical Center, Amsterdam, The Netherlands4Department of Health Science, University Medical Center, Utrecht, The Netherlands5Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands Delirium is the most common acute neuropsychiatric disorder in hospitalized elderly. The Dutch version of the Delirium Rating Scale-Revised-98 (DRS-R-98) appears to be a reliable method to classify delirium. The aim of thisstudy was to determine the validity and reliability of the DRS-R-98 and to study clinical subtypes of delirium using the DRS-R-98.
Methods Patients received the Dutch version of the DRS-R-98, the Mini-Mental State Examination, the Confusion Assessment Method, and a clinical diagnosis of delirium according to DSM-IV criteria, and their relatives the InformantQuestionnaire Cognitive Decline in the Elderly.
Results The DRS-R-98 validation cohort (n ¼ 65) consisted of 23 patients with delirium, 22 patients with dementia, and 20 non-psychiatric comparison patients. For the delirium subtype study, a second cohort comprising 54 delirious patients wasinvestigated. Median DRS-R-98 scores significantly distinguished delirium from dementia and no psychiatric disorder. Inter-rater reliability (intra-class correlation 0.97) and internal consistency (Crohnbach's alpha 0.94) were high. Positive scores ofDRS-R-98 item 4 (affect liability) and item 7 (motor agitation) predicted the presence of non-hypoactive delirium, with aspecificity of 89% and a sensitivity of 57%.
Conclusion The results show that the Dutch version of the DRS-R-98 is a valid and reliable measure of delirium severity and distinguishes patients with delirium from patients with dementia and comparison patients. Furthermore, the DRS-R-98 isable to exclude hypoactive delirium. Copyright # 2006 John Wiley & Sons, Ltd.
key words - delirium; DRS; reliability; subtype; treatment increased length of stay, increased morbidity andmortality, and higher hospital costs (Francis et al., Delirium is an acute neuropsychiatric syndrome, 1990; O'Keeffe and Lavan, 1997; Dolan et al., 2000; characterized by deranged consciousness, cognitive Ely et al., 2001; McCusker et al., 2003).
and attentional disturbances, and with a typical Lipowski (1983) classified delirium into three fluctuating course. Delirium is common in elderly subtypes, based on different symptom patterns, i.e.
hospitalized patients and is associated with many hyperactive, hypoactive, and mixed presentations of serious short- and long-term consequences including delirium (Lipowski, 1983). Hyperactive patients arerestless, agitated, and often suffering from hallucina-tions and delusions. Hypoactive patients appear *Correspondence to: Dr S. E. de Rooij, Academic Medical Center, lethargic, drowsy, sedated, respond slowly to ques- Department of Internal Medicine, F4-159, PO Box 22700, 1100 DEAmsterdam, The Netherlands. E-mail: s.e.derooij@amc.uva.nl tions, do not move much and are often misdiagnosed Copyright # 2006 John Wiley & Sons, Ltd.
as being depressed. Patients with the mixed subtype dementia is required for adequate treatment of these conditions. Furthermore, in case of a delirium, a In order to diagnose delirium and to assess its correct classification of the subtype of delirium is symptom profile and severity, many different instru- required, also for treatment purposes (Johnson et al., ments have been developed both for clinical and 1994; Marcantonio et al., 2002). Indeed, especially the research use. Frequently used scales for diagnosing hyperactive delirium subtype may need drug treat- delirium are the Confusion Assessment Method (CAM) ment, whereas no evidence exists for the use of (Inouye et al., 1990), the Delirium Symptom Interview antipsychotic medication in hypoactive delirium (DSI) (Albert et al., 1992), the Memorial Delirium Assessment Scale (MDAS) (Breitbart et al., 1997) and At the moment, it is not known whether the DRS-R- the Saskatoon Delirium Checklist (SDC) (Miller et al., 98 may be used to distinguish between the several 1988). Symptom profile and severity of a delirium can subtypes of delirium in elderly hospitalized patients.
be assessed with the Delirium Rating Scale (DRS) Hence, the aim of the present study was to (Trzepacz et al., 1988), the MDAS (Breitbart et al., investigate and validate the DRS-R-98 in a consecu- 1997), the Confusional State Evaluation (CSE) tive series of hospitalized elderly patients in Internal (Robertsson et al., 1997), the Delirium Assessment medicine and surgical wards of a general hospital. For Scale (DAS) (O'Keeffe, 1994) and the Delirium Index this purpose, the DRS-R-98 was translated into the (DI) (McCusker et al., 1998). Subtypes of delirium Dutch language. A second aim of the study was to have been identified with the DAS (O'Keeffe, 1999), assess whether the DRS-R-98 is capable of identifying the DSI (Albert et al., 1992), the MDAS (Breitbart delirium subtypes within a cohort of elderly patients.
et al., 1997) and the criteria of Liptzin and Levkoff(Liptzin and Levkoff, 1992).
The most widely used instrument to diagnose delirium and to assess its severity is the DRS (Trzepacz et al., 1988). It is a ten-item observational A series of 119 patients aged 65 years and older who clinician-rated scale that assesses and scores symp- were admitted to the Departments of Internal Medicine toms of delirium. The DRS has been translated in nine and Surgery of the Academic Medical Center, a languages, and has been used in studies on clinical general university teaching hospital, were eligible to phenomenology, pathophysiology, treatment and out- participate. All patients (or their relatives) were come of delirium (Trzepacz and Dew, 1995). In a cross informed about the procedures and were asked to validation study it proved to be reliable and valid in a give informed consent. The study was part of a larger, population of older hospitalized patients with a ongoing study and was approved by the Medical relatively high incidence of delirium (Rockwood Ethical Committee of our institution.
A first cohort of 65 patients participated in the The DRS however, had some limitations. Only a validation and reliability study of the Dutch version of limited number of items concerning cognitive symp- the DRS-R-98. This DRS-R-98 validation cohort toms were included in the DRS, moreover a specific consisted of 23 consecutive patients with delirium, item on attention, being a core symptom of delirium, 22 consecutive patients with dementia, and 20 conse- was lacking. To meet with these problems the revised cutive non-psychiatric comparison patients.
version of the DRS, the DRS-R-98, was developed Subsequently, a second cohort of 54 consecutive (Trzepacz et al., 2001). The DRS-R-98 has been delirious patients was included in the subtype analysis demonstrated to be reliable and valid in distinguishing study. All patients in both cohorts were studied within patients with delirium from non delirious psychiatric 48 h of admission. A more extended description of the patients. Furthermore, it proved to be an adequate whole cohort has already been published (Korevaar instrument to assess the severity of delirium (Meagher The DRS-R-98 was originally validated among elderly patients with pre-existent dementia, schizo- phrenia, depression and other psychiatric illnesses, butso far not in non-psychiatric controls, admitted to a DRS-R-98. The DRS-R-98 is a 16-item observational general hospital and at risk for delirium. Elderly clinician rated scale with a maximum total severity hospitalized patients might show various cognitive score of 39 points. One section, consisting of three- disorders and a proper distinction between delirium or items, focuses on features related to the diagnostic Copyright # 2006 John Wiley & Sons, Ltd.
Int. J. Geriatr Psychiatry 2006; 21: 876-882.
features of delirium (temporal onset of symptoms, considered to have serious cognitive decline, i.e.
fluctuation of symptoms, and physical etiology). The dementia. The IQCODE is not a test of cognitive other section is a 13-item severity scale that is used for function per se, because behavioural observations as repeated measurements. The severity items cover well as cognitive testing completes the diagnostic language, and thought processes, two items on motoric process. Nevertheless, the IQCODE has proven to be a presentation and five items concerning cognition. All widely applicable and efficient screening method for items contain gradations of symptom intensity and each cognitive decline in elderly patients. The Confusion response alternative may be rated 0 to 3 points. Ratings Assessment Method (CAM) is a sensitive, specific, concern a 24-h period using all available information reliable, and easy to use instrument for identification from family, nurses, doctors and medical records.
of delirium (Inouye et al., 1990). All measurements The scale was already established as valid and were performed within 48 h after hospital admission.
reliable, and was able to distinguish patients withdelirium from non delirious psychiatric patients.
Furthermore, it proved to be a severity measure ofdelirium (Trzepacz et al., 2001). For assessment of Validation of the Dutch version of the DRS-R-98. All orientation, direct recall, short term memory, and visio- patients for the validation and reliability study were spatial ability corresponding MMSE-items (items 11, evaluated simultaneously by two investigators (experi- 12, and 13, respectively) were applied. Whenever an enced geriatricians and consultation-liaison psychia- item of the DRS-R-98 could not be rated, it was trist) who were blind to each others ratings, within 48 h assigned 1.5 points as suggested (Trzepacz et al., 2001).
of admission. All research physicians were trained inapplying the DRS-R-98. A psychiatric diagnosis, Translation of the DRS-R-98. The translation procedure according to DSM-IV criteria, based on all available of the DRS-R-98 was approved by the developer of the clinical information was made by the consulting original DRS-R-98 (P.T. Trzepacz). The DRS-98-R physician and the other non-consulting physician was (including instructions, items, and response choices) was translated into Dutch by two experiencedpsychiatrists in consultation-liaison psychiatry and Delirium subtype analysis. For the study on delirium delirium research (H. Sno and R.C. van der Mast).
subtypes, 54 consecutive delirious patients according Both were native Dutch speakers who speak English to DSM-IV criteria were assessed with the DRS-R-98 fluently (Sno and van der Mast, 2004). Back-translation within 48 h after admission to the hospital. Delirium was done by two native English speakers fluent in was classified into the subtypes hypoactive delirium Dutch. A conference meeting was organized to reach (no hyperactive symptoms) and non- hypoactive consensus about a few minor differences between the delirium ( ¼ hyperactive or mixed) according to the original translation and the back-translation.
clinical presentations as described by Lipowski (1983)and based on the classification system developed by The MMSE, the IQCODE and the CAM. The Mini Liptzin and Levkoff (1992). These authors classified Mental State Examination (Folstein et al., 1975) was patients with more than four hypoactive symptoms performed in all patients in order to screen for at any time during their hospital stay as having cognitive decline at hospital admission, a score of hypoactive delirium, and patients with three or more 24 points was used as a cut off score for cognitive hyperactive symptoms as having hyperactive delirium subtype. Patients who scored high on both types of Questionnaire Cognitive Decline in the Elderly symptoms were considered to have mixed type (IQCODE) (Jorm et al., 1991) was administered to the informants related to the patients to obtaininformation about the possible presence of pre-morbid cognitive impairment prior to admission. We askedthem to answer questions concerning the patients' Data were analyzed using SPSS-PC software version cognition according to the condition the patient was in 11.5. Group comparisons for the DRS-R-98 validation two weeks prior to the illness that had caused the study were based on hospitalized elderly patients meeting DSM IV criteria for: (1) delirium (n ¼ 23); The score is an average of the 16-item scores, each (2) dementia (Alzheimer/ MID/not otherwise speci- rated from 1 (much improved) to 5 (much worse).
fied; n ¼ 22); or (3) having no delirium or dementia Patients with a mean score of 3.9 or more were (n ¼ 20). Rating scale data were expressed median Copyright # 2006 John Wiley & Sons, Ltd.
Int. J. Geriatr Psychiatry 2006; 21: 876-882.
scores and range because of the their distribution.
were based on hospitalized patients meeting DSM-IV Differences in baseline characteristics were tested criteria for dementia (n ¼ 22) (Alzheimer/ MID/not with chi-square tests or with the Mann-Whitney U test. Inter rater agreement was assessed by analysis (n ¼ 23) with a delirium, and patients (n ¼ 20) who of variance and expressed as intra-class correlation had no psychiatric illnesses. The delirium and (ICC). ICC was calculated using two-way random dementia groups were similar in age as the compari- sons were younger as might be expected from the Inter-rater reliability for each DRS-R-98 item and different age distributions of the illnesses studied. The for the DRS-R-98 total severity score were assessed by MMSE score for the delirium group was significantly using an intra-class coefficient (ICC) for pairs of lower compared to the patients with dementia and the independent raters, given that the total scores of the patients without any psychiatric illness, while the DRS-R-98 indicate increasing severity of delirium.
DRS-R-98 and the IQCODE were significantly higher Reliability of the measured scores was assessed by in delirious patients compared to the comparisons and establishing the extent to which the measured variance the demented patients (p < 0.05). The DRS-R-98 in a score reflected the true score, rather than random score did not differ among dementia or comparisons.
error. Because of fluctuating course and variability of The median score on the DRS-R-98 severity scale symptoms of delirium, test-retest variability was not for the different diagnostic groups as scored by the two carried out. Scores for each DRS-R-98 item were raters is presented in Table 2. Median score for correlated with DRS-R-98 total severity scale scores, delirious patients was 22 (range 7-39), patients with using Cronbach's alpha coefficient to assess internal dementia had a median score of 5, and patients without consistency of the scale as a measure of the severity of any psychiatric disorder scored 1 point, these scores delirium. A minimum reliability of 0.70 has been were significantly different (p < 0.001). In the recommended for scales used in group level analysis.
subsequent post-hoc analyses, scores between all Multiple logistic regression analysis was used to three groups were significantly different from each identify items associated with an increased or other (all p-values <0.001). Median scores for all decreased risk of having hyperactive or mixed subtype types of patients were similar between both raters, as of delirium, and thus not having hypoactive delirium.
were missing scores for DRS items (scored 1.5 points) A forward selection procedure was applied entering that mostly concerned item 13 (visio-spatial ability).
only items with a p-value <0.05 into the model.
Inter-rater variability and internal consistency The inter-rater reliability of the Dutch version of the DRS-R-98 severity scale between both raters was 0.97 The baseline characteristics of the DRS-R-98 vali- [95% Confidence Intervel (CI): 0.96-0.98], while the dation cohort are given in Table 1. Group comparisons Cronbach's alpha coefficient was 0.94 (the range of Baseline characteristics of the DRS-R-98 validation cohort (n ¼ 65) # Note: #Diagnostic groups are based on the scores of the DSM-IV (delirium yes or no), and on the MMSE, IQCODE and DSM IV (dementiayes or no).
ÃÃÃbroadest range as scored by two raters; MMSE ¼ Mini Mental State Examination; IQCODE ¼ Informant Questionnaire Cognitive Declinein the Elderly; DRS-R-98 ¼ Delirium Rating Scale-R-98.
Copyright # 2006 John Wiley & Sons, Ltd.
Int. J. Geriatr Psychiatry 2006; 21: 876-882.
DRS-R-98 scores in delirium, dementia and comparisons Percentage of patients with positive scores (!1 point) on the DRS-R-98-items among patients (n ¼ 54) with hypoactive andnon-hypoactive delirium Rater 1 Rater 2 Rater 1 Rater 2 Rater 1 Rater 2 Note: DRS-R-98 ¼ Delirium Rating Scale-R-98.
subtype group (22.5; range 6-36), showing no relation between DRS-R-98 severity score and delirium Multivariate logistic regression analysis to identify Note: Ãscores for DRS-R-98, DSM-IV and CAM were significantlydifferent between all groups (all p-values <0.001); CAM ¼ Confu- items predicting for the probability of having non- Confusion Assessment Method; DRS-R-98 ¼ Delirium Rating hypoactive delirium subtype resulted in item 4 (affect liability) and item 7 (motor agitation). Patients whoscored positive on both item 4 and 7 [odds ratio (OR)26.7; 95% CI 3.7-190] as well as patients with a the Cronbach's alpha coefficient if one item was positive score on either item 4 or item 7 [OR 3.6; 95% CI 0.7-17) were more at risk for non-hypoactivedelirium. A positive score on both item 4 and 7 todetect non-hypoactive delirious patients showed a sensitivity of 57%, a specificity of 89%, and a positive A second series of 54 consecutive patients with a predictive value of 91%. The negative predictive value delirium (median age 83.0 years, range 68-95 years, for either item 4 or 7 positive or both negative was only 54.7% men) were enrolled in the subgroup analysis.
47%. This implicates that this algorithm misses many The median score of the IQCODE was 4.34 (range patients with a non-hypoactive, but that less patients 2.81-5.0) showing that almost all patients with a with a hypoactive delirium are wrongly classified as delirium already experienced pre-morbid cognitive decline. The median MMSE score was 12.8 (range2-29).
In Table 3 the number of patients scoring on the different items of the DRS-R-98 severity scale areshown for the hypoactive and non-hypoactive delirium This study shows that the Dutch version of the DRS-R- groups. According to the criteria of Liptzin and 98 was able to differentiate patients with delirium Levkoff 19 patients (35%) showed hypoactive from demented as well as from non-psychiatric delirium, and 35 patients (65%) non-hypoactive patients. The DRS-R-98 also proved to be a valid delirium or mixed type delirium. No significantly and reliable severity measure for delirium as demon- difference (p ¼ 0.20) was found between the median strated by a high inter-rater reliability and internal scores of the DRS-R-98 in the hypoactive delirium consistency. Further, hypoactive and non-hypoactive group (21; range 11-29) and the non-hypoactive delirium could be discerned. Non-hypoactive delirium Copyright # 2006 John Wiley & Sons, Ltd.
Int. J. Geriatr Psychiatry 2006; 21: 876-882.
was best predicted by a positive score on the DRS-R- 98 items 'affect liability' and/or 'motor agitation'.
One limitation of this study is that due to the design of our study possible fluctuations in symptoms of the delirium during the hospital stay may have beenmissed. The DRS-R-98 permits repeated adminis-tration within a 24-hour period of time. We did not, however, validate the Dutch version of the DRS-R-98 for repeated use and further studies may necessary to study also this aspect of the Dutch version.
The results of our study are in line with several studies who underlined the good reliability of (translated versions of) the DRS and the DRS-R-98 and with most of the studies using delirium severity rating scales other than the DRS (see Table 4).
Furthermore, median scores and ranges of the Dutch version of the DRS-R-98 in the delirium and dementia groups are comparable with the results of In this study it was demonstrated that the DRS-R-98 is able to differentiate between patients with a non- hypoactive delirium subtype and patients with a hypoactive delirium subtype. The possible implica- tions of this subtype classification may be several. The investigation and exploration of clinical subtypes of delirium may provide information concerning the etiology, the pathogenesis, and the prognosis of delirium, but also may have therapeutic consequences.
Only few studies have tried to evaluate the relevance of clinical subtypes of delirium or performed asystematic investigation concerning the clinical features in order to study whether a significance of delirium subtypes can be identified (Trzepacz and Dew, 1995; Camus et al., 2000). The studies described show different results, partly due to methodological problems and possibly by lack of a standard classification for delirium subtypes.
However, the results of this study make the DRS-R- 98 well suited for use in research for delirium treatment strategies in hypoactive and non-hypoactive delirium, but further studies are necessary to support In our sample consisting of internal medicine and surgical patients dissimilar frequencies of the different delirium subtypes than reported by Liptzin and Levkoff (1992) were found. The scored criteria according to Liptzin and Levkoff may be different when they should be scored one day later, because of a variation of delirium symptoms. Another possible bias may be the fact that the different frequencies of a hypoactive delirium subtype may depend on the studied population (Table 4). Marcantonio found, in a group of postoperatively delirious hip fracture Copyright # 2006 John Wiley & Sons, Ltd.
Int. J. Geriatr Psychiatry 2006; 21: 876-882.
patients, even 71% patients with a hypoactive Inouye SK, van Dyck CH, Alessi CA, Balkin S, Siegal AP, Horwitz delirium, measured with another instrument, the RI. 1990. Clarifying confusion: the confusion assessment method.
A new method for detection of delirium. Ann Intern Med 113 (12):941-948.
The Dutch version of the DRS-R-98 is a valid and Jorm AF, Scott R, Cullen JS, MacKinnon AJ. 1991. Performance of reliable measurement instrument of the severity of the Informant Questionnaire on Cognitive Decline in the Elderly delirium, as shown by a high inter-rater reliability and (IQCODE) as a screening test for dementia. Psychol Med 21 (3): internal consistency. This instrument is also able to distinguish between patients with a delirium, patients Johnson J, Sims R, Gottlieb G. 1994. Differential diagnosis of dementia, delirium and depression. Implications for drug therapy.
with dementia without delirium, and comparison patients. Furthermore, items of the DRS-R-98 are Korevaar JC, van Munster BC, de Rooij SE. 2005. Risk factors for useful for the exclusion of the presence of a hypoactive delirium in acutely admitted elderly patients: a prospective cohort Lipowski ZJ. 1983. Transient cognitive disorders (delirium, acute Interestingly, our study concerning the delirium confusional states) in the elderly. Am J Psychiatry 140 (11): subtypes may also offer some practical treatment consequences. A positive score on both item 4 and 7 Liptzin B, Levkoff SE. 1992. An empirical study of delirium excludes a hypoactive delirium, and therefore specific subtypes. Br J Psychiatry 161: 843-845.
Marcantonio E, Ta T, Duthie E, Resnick NM. 2002. Delirium and symptomatic, medical treatment can be started.
severity and psychomotor types: their relationship with outcomes The possibility that patients with a hypoactive delirium after hip fracture repair. J Am Geriatr Soc 50 (5): 850-857.
are misdiagnosed is 11%. In case of excluding a McCusker J, Cole M, Dendukuri N, Han L, Belzile E. 2003. The hypoactive delirium a quick and safe decision course of delirium in older medical inpatients: a prospective concerning the start of symptomatically medical study. J Gen Intern Med 18 (9): 696-704.
Meagher DJ, O'Hanlon D, O'Mahony E, Casey PR, Trzepacz PT.
treatment interventions can therefore be provided.
1998. Relationship between etiology and phenomenologic profile This is in order to protect a patient properly from in delirium. J Geriatr Psychiatry Neurol 11 (3): 146-149.
adverse events or hospital complications directly or McCusker J, Cole M, Bellavance F, Primeau F. 1998. Reliability and indirectly caused by his delirious symptoms.
validity of a new measure of severity of delirium. Int Psychoger-iatr 10 (4): 421-433.
However, it is important to emphasize that Miller PS, Richardson JS, Jyu CA, Lemay JS, Hiscock M, Keegan treatment options for hypoactive delirium have not DL. 1988. Association of low serum anticholinergic levels and been subject of (randomized) clinical trials.
cognitive impairment in elderly presurgical patients. Am J Psy-chiatry 145 (3): 342-345.
O'Keeffe ST. 1994. Rating the severity of delirium: The Delirium Assessment Scale. In Int J Geriatr Psychiatry 9: 551-556.
O'Keeffe S, Lavan J. 1997. The prognostic significance of delirium Albert MS, Levkoff SE, Reilly C, et al. 1992. The delirium symptom in older hospital patients. J Am Geriatr Soc 45 (2): 174-178.
interview: an interview for the detection of delirium symptoms in O'Keeffe ST. 1999. Clinical subtypes of delirium in the elderly.
hospitalized patients. J Geriatr Psychiatry Neurol 5 (1): 14-21.
Dement Geriatr Cogn Disord 10 (5): 380-385.
Breitbart W, Rosenfeld B, Roth A, Smith MJ, Cohen K, Passik S.
Robertsson B, Karlsson I, Styrud E, Gottfries CG. 1997. Confu- 1997. The Memorial Delirium Assessment Scale. J Pain Symptom sional State Evaluation (CSE): an instrument for measuring severity of delirium in the elderly. Br J Psychiatry 170: 565- Breitbart W, Tremblay A, Gibson C. 2002. An open trial of olanzapine for the treatment of delirium in hospitalized cancer Rockwood K, Goodman J, Flynn M, Stolee P. 1996. Cross-validation patients. Psychosomats 43 (3): 175-182.
of the Delirium Rating Scale in older patients. J Am Geriatr Soc Camus V, Burtin B, Simeone I, Schwed P, Gonthier R, Dubos G.
2000. Factor analysis supports the evidence of existing hyper- de Rooij SE, Schuurmans MJ, van der Mast MJ, Levi M. 2005.
active and hypoactive subtypes of delirium. Int J Geriatr Psy- Clinical subtypes of delirium and their relevance for daily clinical practice. A systematic review. Int J Geriatr Psychiatry 20 (7): Dolan MM, Hawkes WG, Zimmerman SI, et al. 2000. Delirium on hospital admission in aged hip fracture patients: prediction of Sno HN, van der Mast RC. 2004. Delirium Rating Scale-R-98-NL.
mortality and 2-year functional outcomes. J Gerontol A Biol Sci In Richtlijn Delirium. Nederlandse Vereniging voor Psychiatrie.
Ely EW, Gautam S, Margolin R, Francis J, May L, Speroff T, Trzepacz PT, Baker RW, Greenhouse J. 1988. A symptom rating Truman B, Dittus R, Bernard R, Inouye SK. 2001. The impact of scale for delirium. Psychiatry Res 23 (1): 89-97.
delirium in the intensive care unit on hospital length of stay.
Trzepacz PT, Dew MA. 1995. Further analyses of the Delirium Intensive Care Med 27 (12): 1892-1900.
Rating Scale. Gen Hosp Psychiatry 17 (2): 75-79.
Folstein MF, Folstein SE, McHugh PR. 1975. 'Mini-mental state'. A Trzepacz PT, Mittal D, Torres R, Kanary K, Norton J, Jimerson N.
practical method for grading the cognitive state of patients for the 2001. Validation of the Delirium Rating Scale-revised-98: clinician. J Psychiatr Res 12 (3): 189-198.
comparison with the delirium rating scale and the cognitive test Francis J, Martin D, Kapoor WN. 1990. A prospective study of for delirium. J Neuropsychiatry Clin Neurosci 13 (2): 229- delirium in hospitalized elderly. JAMA 263 (8): 1097-1101.
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Int. J. Geriatr Psychiatry 2006; 21: 876-882.

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