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Clinical utility and validation of the Japanese version of Memorial Delirium Assessment Scale in a psychogeriatric inpatient setting
General Hospital Psychiatry 23 (2001) 36 – 40
Clinical utility and validation of the Japanese version of Memorial Delirium Assessment Scale in a psychogeriatric inpatient setting Yutaka Matsuokaa,*, Yuko Miyakeb, Hiroshi Arakakia, Kuniaki Tanakaa, Toshinari Saekic, Shigeto Yamawakic a
Department of Psychiatry, Tokyo Metropolitan Tama Geriatric Hospital, Higashimurayoma, Japan Department of Mental Health Administration, National Institute of Mental Health, National Center for Neurology and Psychiatry, Ichikawa, Japan c Department of Psychiatry and Neurosciences, Hiroshima University School of Medicine, Hiroshima, Japan
b
Abstract Delirium is a common mental disorder in the elderly. The Memorial Delirium Assessment Scale (MDAS) was developed in 1997 to assess delirium severity over time. The purpose of the current prospective study is to assess the clinical utility, diagnostic potential, reliability and validity of the Japanese version of MDAS in a psychogeriatric unit setting. Reliability was examined by testing 37 elderly patients; validity was examined concurrently by 16 patients with delirium. Two psychiatrists evaluated each patient simultaneously. Mean MDAS ratings differed among groups of patients with delirium, dementia, or no cognitive impairment. High levels of consistency within raters (Cronbach’s alpha⫽0.92) and reliability between raters (0.98) were indicated. The correlation between MDAS scores and rating on the Delirium Rating Scale (r⫽.74, P⫽.0011), the Clinician’s Global Rating of delirium severity (r⫽.67, P⫽.0047), and the Mini Mental State Examination (r⫽⫺.54, P⫽.029) was fair. The MDAS seems to be a reliable measuring instrument for assessing delirium in elderly patients. © 2001 Elsevier Science Inc. All rights reserved. Keywords: Delirium; Dementia; Aged; Severity assessment; Geriatric population
1. Introduction Delirium is one of the most frequent and important psychiatric problems in general hospital psychiatry, and the management and treatment of patients with delirium represent an essential function of the attending psychiatrist. Approximately 18% of general hospital patients develop delirium during hospitalization [1]. Advanced age is a recognized risk factor for delirium [2], and given the projected increase in the elderly population in the next 20 years [3], the need for tools to aid in the diagnosis and assessment of delirium is likely to assume even greater clinical importance in elderly patients. Unfortunately there are no valid delirium assessment tools for the geriatric population in Japan. The Memorial Delirium Assessment Scale (MDAS) is an instrument designed to measure the severity of delirium and therefore captures behavioral manifestations as well as cog-
* Corresponding author. Psycho-Oncology Division, National Cancer Center Research Institute East, 6 –5-1 Kashiwanoha, Kashiwa, Chiba, 2778577 Japan. Tel.: ⫹81-471-34-7013; fax: ⫹81-471-34-7026. E-mail address: [email protected] (Y. Matsuoka).
nitive deficit [4]. This physician-rated instrument measures relative impairment in domains itemized as follows: awareness, orientation, short term memory, digit span, attention capacity, organizational thinking, perceptual disturbance, delusions, psychomotor activity, sleep-wake cycle. Although designed primarily to rate delirium severity, the initial phase of the validation study by Breitbart et al. [4] examined the diagnostic potential of the MDAS and established the diagnostic cutoff score to be 13. This phase involved a heterogeneous group of 33 mixed cancer and AIDS patients. And Lawlor et al. [5] have recently performed a further validation study of the MDAS in an acute palliative care unit and showed their diagnostic cutoff score to be 7. As above, MDAS has only been validated in cancer and AIDS patients. Its accuracy in assessing delirium severity among elderly patients admitted to a psychiatric ward for evaluation and treatment of psychiatric illness has not been previously addressed. The purpose of this study was to assess the clinical utility, diagnostic potential and validation of the Japanese version of MDAS in a psychogeriatric population with diagnosis of delirium that met DSM-IV criteria. [6].
0163-8343/01/$ – see front matter © 2001 Elsevier Science Inc. All rights reserved. PII: S 0 1 6 3 - 8 3 4 3 ( 0 0 ) 0 0 1 2 1 - 3
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40
2. Methods 2.1. Subjects and procedures For our validation study, we enrolled 37 elderly patients newly hospitalized in psycho-geriatric unit of Tokyo Metropolitan Tama Geriatric Hospital between December 1998 and October 1999. A resident psychiatrist assessed each patient immediately after admission. Patients meeting DSM-IV criteria for delirium then automatically underwent MDAS testing to assess delirium severity by two psychiatrists simultaneously. All patients had provided their written or verbal informed consent to be evaluated for the purposes of this study after discussing the risks and benefits of participation with an experienced psychiatrist (Y.M.). One psychiatrist (H.A.) rated patients using MDAS instrument, while a second psychiatrist (Y.M.) rated patients with the following instruments: MDAS, the Mini-Mental State (MMS) [7,8], the Delirium Rating Scale (DRS) [9,10], and Clinician’s Global Rating (CGR) of delirium severity (none, mild, moderate, or severe). For the control subjects, we used patients who had been diagnosed with other psychiatric disorders also using DSM-IV criteria as with the subjects. Demographic and medical information was obtained from the patients’ hospital records. Because this study focused on confirming the reliability and validity of MDAS ratings, such information as patients’ demographic characteristics, course of illness, or other measures of psychological functioning was not collected. The Institutional Ethical Review Board of Tokyo Metropolitan Tama Geriatric Hospital approved this study. 2.2. Rating scales 2.2.1. Memorial Delirium Assessment Scale (MDAS) The MDAS is a ten-item, four point clinician-rated scale (possible range, 0 –30) designed to quantify the severity of delirium in medically ill patients. Items included in the MDAS reflect the diagnostic criteria for delirium in the DSM-IV. Scale items assess disturbance in arousal and level of consciousness, as well as several areas of cognitive functioning (memory, attention, orientation, disturbance in thinking) and psychomotor activity. We require approximately 10 min to administer this test, then integrate behavioral observations and objective cognitive testing. Validation study of the MDAS was accomplished at the Memorial Sloan-Kettering Cancer Center and reported by Breitbart et al. in 1997 [4]. An experienced consultation-liaison psychiatrist (Y.M.) translated the MDAS into Japanese with Dr. Breitbart’s permission and went through the back-translation process to create the Japanese version of the Memorial Delirium Assessment Scale.
37
2.2.2. Mini-Mental State (MMS) The MMS [7,8] rating scale is one of the most frequently utilized cognitive screening tools. Scores on the MMS rating scale range from 30 (no impairment) to 0. Although the MMS rating scale has demonstrated internal consistency and test-retest reliability, it is not intended for use as a diagnostic instrument per se. Scores suggestive of impairment correspond to some form of cognitive disorder, but the determination of impairment is not specific to delirium. Mori et al. reported the validation study of the Japanese version of the MMS rating scale [8]. 2.2.3. Delirium Rating Scale (DRS) The DRS [9,10] is a ten-item diagnostic tool designed to generate valid, reliable diagnoses of delirium in medically ill patients. This instrument, which is among those most widely used, discriminates between patients with and without delirium and has been used as a measure of delirium severity despite limitations. Although the Japanese version of the DRS has not yet been validated, this study uses it for the sake of convenience [10]. 2.2.4. Clinician’s Global Rating of delirium severity (CGR) The CGR is an ordinal classification system by which a clinician rates the severity of delirium along a 0 –3 scale corresponding to none, mild, moderate, and severe. 2.3. Statistical analysis Analyses were performed in this study using HALBAU for Windows software. One-way analysis of variance (oneway ANOVA) and Scheffe’s test were used to assess whether the MDAS, DRS, and MMS scores, patient age, and performance status significantly differentiated patients with delirium from patients with other psychiatric disorders. Interitem reliability between items of the MDAS was established by calculating Cronbach’s coefficient alpha for the ten-item scale. Reliability between raters was established by calculating intraclass correlation coefficients for the total scale as well as for individual items. Concurrent validity of the MDAS was established by calculating Pearson productmoment correlation coefficients for the MDAS total score and the individual MDAS ratings with the DRS and MMS. Spearman rank-order correlation coefficients were used to assess the relationship between MDAS total score and the individual MDAS item with CGR.
3. Results 3.1. Clinical utility The mean age of the subjects was 75.1 years, and 67.6% of the subjects were female. Sixteen subjects met the DSM-IV criteria for delirium, 7 met the diagnostic criteria
38
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40 Table 2 Sensitivity and Specificity of the Japanese version of MDAS (n ⫽ 37)
Table 1 Demographic Characteristics of 36 Elderly Subjects Diagnostic group
N
Sex female
Age mean (SD)
PS mean (SD)
Delirium Dementia Mood Disorders Schizophrenia
16 7 10 3
8 4 9 3
77.44 (5.35)a 77.43 (4.31)a 70.40 (7.86)a 72.33 (5.31)a
2.69 (0.92)b 0.43 (0.50)b,c 0.10 (0.30)b,c 0.00 (0.00)b,c
a
P⬍0.05 by one way ANOVA P⬍0.00001 by one way ANOVA c P⬍0.00001 by Scheffe’s test (vs. Delirium) PS: Performance Status (Eastern Cooperative Oncology Group’s Scale) b
for dementia (4 for Alzheimer-type dementia and 3 for vascular dementia), 10 had mood disorders (5 with major depressive disorder, 2 with bipolar I disorder, and 3 with dysthymic disorder), and 3 had schizophrenia, and 1 had a conversion disorder. The subjects were organized into groups: delirium, dementia, mood disorders, and schizophrenia. The one patient with the conversion disorder was not assigned to a group. Demographic information about the four groups is shown in Table 1. The average age differed significantly among the four groups [F⫽3.05, df⫽3, 32, P⫽.043]. The patients with delirium had poorer performance status (measured by the Eastern Cooperative Oncology Group’s Scale) than the other three groups. The MDAS score differed significantly among the four groups [F⫽51.44, df⫽3, 32, P⬍.00001]. The average MDAS scores were 18.31 (SD⫽4.25) for the patients with delirium, 6.14 (SD⫽2.10) for the patients with dementia, 3.80 (SD⫽2.04) for the patients with mood disorders, and 2.33 (SD⫽0.94) for the patients with schizophrenia. Posthoc contrast analyses (Scheffe’s test) demonstrated that patients with delirium had significant higher MDAS scores than those of the patients with dementia (F⫽21.10, df⫽3, 32, P⬍.00001), the patients with mood disorders (F⫽37.92, df⫽3, 32, P⬍.00001), and the patients with schizophrenia (F⫽18.87, df⫽3, 32, P⬍.00001). There was no significant difference in MDAS scores between patients with dementia
Cutoff score
Sensitivity
Specificity
7 8 9 10 11 12 13
1.00 1.00 1.00 1.00 1.00 1.00 0.94
0.81 0.91 0.95 1.00 1.00 1.00 1.00
and patients with mood disorders (F⫽0.66, df⫽3, 32, P⫽NS) or schizophrenia (F⫽0.89, df⫽3, 32, P⫽NS). Average scores on the MMS and DRS assessments differed significantly among the four groups by one-way ANOVA (P⬍.00001). There was a significant difference in MMS scores between patients with delirium and those patients with mood disorders [F⫽22.83, df⫽3, 32, P⬍.00001] or schizophrenia [F⫽8.07, df⫽3, 32, P⫽.00038]. There was also a significant difference in DRS scores between patients with delirium and those patients with dementia [F⫽79.09, df⫽3, 32, P⬍.00001], mood disorders [F⫽117.34, df⫽3, 32, P⬍.00001] or schizophrenia [F⫽55.01, df⫽3, 32, P⬍.00001]. The MDAS cutoff diagnostic scores with relevant sensitivities and specificities are summarized in Table 2. A diagnostic cutoff score of 10 gave optimum results in relation to the presence or absence of delirium. 3.2. Reliability and validity testing Correlational analyses revealed an overall Cronbach’s alpha coefficient of 0.92 based on the MDAS ratings of the principal investigator (Y.M.). The item-total correlations for the ten items ranged from 0.62 to 0.92. The individual item-total correlations and intraclass correlation coefficients are detailed in Table 3. The overall correlation coefficient for the two psychiatrists’ ratings, calculated for the entire
Table 3 Japanese version of Memorial Delirium Assessment Scale Reliability Data MDAS item
Mean
SD
Alpha if removed
Item-total r
Intra-class r
1 2 3 4 5 6 7 8 9 10
0.78 1.62 1.54 1.11 0.84 0.73 0.73 0.76 1.19 1.05
1.00 1.36 0.80 1.13 1.07 0.96 1.07 0.90 1.13 0.78
0.90 0.92 0.92 0.91 0.90 0.90 0.91 0.92 0.91 0.91
0.91 0.65 0.63 0.75 0.92 0.89 0.75 0.62 0.78 0.76
0.90 0.99 0.96 1.00 0.86 0.87 0.93 0.85 0.91 0.92
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40
39
scale, was 0.98. Individual items varied in reliability between raters; the intraclass correlation coefficients ranged from 0.85 to 1.00 (Table 3). In addition, correlational analyses revealed an overall Cronbach’s alpha coefficient of 0.94 based on the DRS ratings of the principal investigator (Y.M.). The item-total correlations for the ten items ranged from 0.65 to 0.95. The scores on the MDAS assessments correlated fairly well with scores on the CGR assessment (r⫽.67, P⫽.0047), the DRS assessment (r⫽.73, P⫽.0011) and the MMS assessment (r⫽⫺.54 P⫽.029).
lation and a high reliability coefficient between raters in our study. This difference signifies that in our study, we investigated patients before they had received any treatment for delirium, while Breitbart et al. investigated patients that had already received some degree of treatment for delirium. [4]. Correlation between CGR and MDAS scores, DRS and MDAS, MMS and MDAS were lower in our study than that of Breitbart et al. (r⫽.67 and 0.89, r⫽.73 and 0.88, r⫽⫺.54 and– 0.91, respectively). The sample used to test concurrent validity in this present study was very small and further study is needed.
4. Discussion
4.1. Clinical implications and limitations
The present results indicate that the Japanese version of the MDAS has acceptable reliability and that this scale is a useful tool for assessing delirium among psycho-geriatric populations. The ten-item MDAS has a high degree of internal consistency, a high level of reliability between two rating psychiatrists and fair degree of concurrent validity with other measures of delirium and delirium severity. Although the MDAS was developed as an instrument for assessing the severity of delirium symptoms, rather than as a diagnostic tool, our results suggest that the MDAS may also be a useful tool for establishing a diagnosis of delirium. The MDAS significantly differentiated between patients with delirium and patients with dementia or noncognitive psychiatric disorders using a cutoff score of 10. Breitbart et al. reported an optimum MDAS diagnostic cutoff score of 13 in the original MDAS validation study [4]. Breitbart et al. acknowledged the potential limitations of the MDAS as a diagnostic instrument, especially in the case of mild delirium [4]. Lawlor et al. suggested an optimum MDAS diagnostic cutoff score of 7 in a further MDAS validation study [5]. Lawlor et al. mentioned its potential to capture a greater population of milder episodes of delirium [5]. However they investigated milder delirium than our study. We suggested that selection of delirium referrals to a psychiatric service, as in the original MDAS validation study [4], could lead to selection bias in favor of more severe delirium than our study. Our study suggests that a nonpsychiatric clinician treated most of the patients with mild to moderate delirium, so only selected patients with moderate to severe delirium were also referred to our department. At any rate, we found that the MDAS was a helpful tool to distinguish delirium from other psychiatric disorders in the psychogeriatric unit setting. Further research with larger, more diverse populations of patients in various clinical settings may also be helpful in determining the most appropriate cutoff score. Although two of the ten MDAS items (items 7 and 8, measuring hallucinations and delusions) were less highly correlated with the overall MDAS score in previous study [4], all ten of the MDAS items had a high item-total corre-
The Japanese version of MDAS is a reliable instrument that measures delirium severity in the elderly. The MDAS appeared to differentiate between patients with delirium and patients with dementia or noncognitive psychiatric disorders using a cutoff score of 10. Since we conducted this study in a clinical context with limited manpower, our study has the limitation of having a modest sample size. Though there are clearly cultural differences between the West and Asia, there is no evidence nor any reason to believes that the expression of delirium differs in different countries. Indeed, the fact that a Western-developed delirium assessment tool could be translated and applied successfully in Japan argues for the generalizability of these reasons to other countries. We hope that further research with this instrument in different clinical settings including a geriatric population in various countries will be performed. Therefore we are now planning the clinical research using the Japanese version of MDAS.
Acknowledgments The authors would like to thank Dr. William Breitbart, Department of Psychiatry, Memorial Sloan-Kettering Cancer Center, for his permission and advice in the translation of MDAS into Japanese. We also thank Dr. Motoko Kondo for her great help with a back-translation of the MDAS, Sister Sabina Sausam at the St. John’s Society Nunnery for language revision and linguistic advice, Dr. Marcus Wenner at Psycho-Oncology Division, National Cancer Center Research Institute East, for kind-hearted comments, and the two anonymous referees for helpful comments on earlier drafts.
References [1] Trzepacz PT, Wise MG. Neuropsychiatric aspects of delirium. In Yudofsky SC and Hales RE (eds), The American Psychiatric Press
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[2] [3]
[4] [5]
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40 Textbook of Neuropsychiatry 3rd edition. Washington, DC, American Psychiatric Press Inc, 1997:447– 470. Schor JD, Levkoff SE, Lipsitz LA, et al. Risk factors for delirium in hospitalized elderly. JAMA 1992;267:827–31. Population. ageing: a public health challenge. World Health organization. URL: http://www.who.int/inf-fs/en/fact135.html [accessed July 18, 2000]. Breitbart W, Rosenfeld B, Roth A, et al. Memorial Delirium Assessment Scale. J Pain Symptom Manage 1997;13:128 –37. Lawlor PG, Nekolaichuk C, Gargon B, et al. Clinical utility, factor analysis, and further validation of the Memorial Delirium Assessment Scale in patients with advanced cancer. Assessing delirium in advanced cancer. Cancer 2000;88:2859 – 67.
[6] American Psychiatric Association. Diagnostic, and Statistical manual of Mental Disorders (4th edn) (DSM-IV). Washington, DC, APA, 1997. [7] Folstein MF, Folstein SE, McHugh PR. “Mini-Mental State” A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975;12:189 –198. [8] Mori E, Mitani Y, Yamadori A. Usefulness of a Japanese version of the Mini-Mental State in neurological patients. Shinkeishinrigaku 1985;1:82–90, (in Japanese). [9] Trzepacz PT, Baker RW, Greenhouse J. A symptom rating scale for delirium. Psychiat Res 1987;23:89 –97. [10] Isse K, Uchiyama M, Tanaka K, et al. Delirium: Clinical findings and its neuro-psychological etiology. Rinsyo seisin yakuri 1998;1:1231– 1242, (in Japanese).
Clinical utility and validation of the Japanese version of Memorial Delirium Assessment Scale in a psychogeriatric inpatient setting Yutaka Matsuokaa,*, Yuko Miyakeb, Hiroshi Arakakia, Kuniaki Tanakaa, Toshinari Saekic, Shigeto Yamawakic a
Department of Psychiatry, Tokyo Metropolitan Tama Geriatric Hospital, Higashimurayoma, Japan Department of Mental Health Administration, National Institute of Mental Health, National Center for Neurology and Psychiatry, Ichikawa, Japan c Department of Psychiatry and Neurosciences, Hiroshima University School of Medicine, Hiroshima, Japan
b
Abstract Delirium is a common mental disorder in the elderly. The Memorial Delirium Assessment Scale (MDAS) was developed in 1997 to assess delirium severity over time. The purpose of the current prospective study is to assess the clinical utility, diagnostic potential, reliability and validity of the Japanese version of MDAS in a psychogeriatric unit setting. Reliability was examined by testing 37 elderly patients; validity was examined concurrently by 16 patients with delirium. Two psychiatrists evaluated each patient simultaneously. Mean MDAS ratings differed among groups of patients with delirium, dementia, or no cognitive impairment. High levels of consistency within raters (Cronbach’s alpha⫽0.92) and reliability between raters (0.98) were indicated. The correlation between MDAS scores and rating on the Delirium Rating Scale (r⫽.74, P⫽.0011), the Clinician’s Global Rating of delirium severity (r⫽.67, P⫽.0047), and the Mini Mental State Examination (r⫽⫺.54, P⫽.029) was fair. The MDAS seems to be a reliable measuring instrument for assessing delirium in elderly patients. © 2001 Elsevier Science Inc. All rights reserved. Keywords: Delirium; Dementia; Aged; Severity assessment; Geriatric population
1. Introduction Delirium is one of the most frequent and important psychiatric problems in general hospital psychiatry, and the management and treatment of patients with delirium represent an essential function of the attending psychiatrist. Approximately 18% of general hospital patients develop delirium during hospitalization [1]. Advanced age is a recognized risk factor for delirium [2], and given the projected increase in the elderly population in the next 20 years [3], the need for tools to aid in the diagnosis and assessment of delirium is likely to assume even greater clinical importance in elderly patients. Unfortunately there are no valid delirium assessment tools for the geriatric population in Japan. The Memorial Delirium Assessment Scale (MDAS) is an instrument designed to measure the severity of delirium and therefore captures behavioral manifestations as well as cog-
* Corresponding author. Psycho-Oncology Division, National Cancer Center Research Institute East, 6 –5-1 Kashiwanoha, Kashiwa, Chiba, 2778577 Japan. Tel.: ⫹81-471-34-7013; fax: ⫹81-471-34-7026. E-mail address: [email protected] (Y. Matsuoka).
nitive deficit [4]. This physician-rated instrument measures relative impairment in domains itemized as follows: awareness, orientation, short term memory, digit span, attention capacity, organizational thinking, perceptual disturbance, delusions, psychomotor activity, sleep-wake cycle. Although designed primarily to rate delirium severity, the initial phase of the validation study by Breitbart et al. [4] examined the diagnostic potential of the MDAS and established the diagnostic cutoff score to be 13. This phase involved a heterogeneous group of 33 mixed cancer and AIDS patients. And Lawlor et al. [5] have recently performed a further validation study of the MDAS in an acute palliative care unit and showed their diagnostic cutoff score to be 7. As above, MDAS has only been validated in cancer and AIDS patients. Its accuracy in assessing delirium severity among elderly patients admitted to a psychiatric ward for evaluation and treatment of psychiatric illness has not been previously addressed. The purpose of this study was to assess the clinical utility, diagnostic potential and validation of the Japanese version of MDAS in a psychogeriatric population with diagnosis of delirium that met DSM-IV criteria. [6].
0163-8343/01/$ – see front matter © 2001 Elsevier Science Inc. All rights reserved. PII: S 0 1 6 3 - 8 3 4 3 ( 0 0 ) 0 0 1 2 1 - 3
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40
2. Methods 2.1. Subjects and procedures For our validation study, we enrolled 37 elderly patients newly hospitalized in psycho-geriatric unit of Tokyo Metropolitan Tama Geriatric Hospital between December 1998 and October 1999. A resident psychiatrist assessed each patient immediately after admission. Patients meeting DSM-IV criteria for delirium then automatically underwent MDAS testing to assess delirium severity by two psychiatrists simultaneously. All patients had provided their written or verbal informed consent to be evaluated for the purposes of this study after discussing the risks and benefits of participation with an experienced psychiatrist (Y.M.). One psychiatrist (H.A.) rated patients using MDAS instrument, while a second psychiatrist (Y.M.) rated patients with the following instruments: MDAS, the Mini-Mental State (MMS) [7,8], the Delirium Rating Scale (DRS) [9,10], and Clinician’s Global Rating (CGR) of delirium severity (none, mild, moderate, or severe). For the control subjects, we used patients who had been diagnosed with other psychiatric disorders also using DSM-IV criteria as with the subjects. Demographic and medical information was obtained from the patients’ hospital records. Because this study focused on confirming the reliability and validity of MDAS ratings, such information as patients’ demographic characteristics, course of illness, or other measures of psychological functioning was not collected. The Institutional Ethical Review Board of Tokyo Metropolitan Tama Geriatric Hospital approved this study. 2.2. Rating scales 2.2.1. Memorial Delirium Assessment Scale (MDAS) The MDAS is a ten-item, four point clinician-rated scale (possible range, 0 –30) designed to quantify the severity of delirium in medically ill patients. Items included in the MDAS reflect the diagnostic criteria for delirium in the DSM-IV. Scale items assess disturbance in arousal and level of consciousness, as well as several areas of cognitive functioning (memory, attention, orientation, disturbance in thinking) and psychomotor activity. We require approximately 10 min to administer this test, then integrate behavioral observations and objective cognitive testing. Validation study of the MDAS was accomplished at the Memorial Sloan-Kettering Cancer Center and reported by Breitbart et al. in 1997 [4]. An experienced consultation-liaison psychiatrist (Y.M.) translated the MDAS into Japanese with Dr. Breitbart’s permission and went through the back-translation process to create the Japanese version of the Memorial Delirium Assessment Scale.
37
2.2.2. Mini-Mental State (MMS) The MMS [7,8] rating scale is one of the most frequently utilized cognitive screening tools. Scores on the MMS rating scale range from 30 (no impairment) to 0. Although the MMS rating scale has demonstrated internal consistency and test-retest reliability, it is not intended for use as a diagnostic instrument per se. Scores suggestive of impairment correspond to some form of cognitive disorder, but the determination of impairment is not specific to delirium. Mori et al. reported the validation study of the Japanese version of the MMS rating scale [8]. 2.2.3. Delirium Rating Scale (DRS) The DRS [9,10] is a ten-item diagnostic tool designed to generate valid, reliable diagnoses of delirium in medically ill patients. This instrument, which is among those most widely used, discriminates between patients with and without delirium and has been used as a measure of delirium severity despite limitations. Although the Japanese version of the DRS has not yet been validated, this study uses it for the sake of convenience [10]. 2.2.4. Clinician’s Global Rating of delirium severity (CGR) The CGR is an ordinal classification system by which a clinician rates the severity of delirium along a 0 –3 scale corresponding to none, mild, moderate, and severe. 2.3. Statistical analysis Analyses were performed in this study using HALBAU for Windows software. One-way analysis of variance (oneway ANOVA) and Scheffe’s test were used to assess whether the MDAS, DRS, and MMS scores, patient age, and performance status significantly differentiated patients with delirium from patients with other psychiatric disorders. Interitem reliability between items of the MDAS was established by calculating Cronbach’s coefficient alpha for the ten-item scale. Reliability between raters was established by calculating intraclass correlation coefficients for the total scale as well as for individual items. Concurrent validity of the MDAS was established by calculating Pearson productmoment correlation coefficients for the MDAS total score and the individual MDAS ratings with the DRS and MMS. Spearman rank-order correlation coefficients were used to assess the relationship between MDAS total score and the individual MDAS item with CGR.
3. Results 3.1. Clinical utility The mean age of the subjects was 75.1 years, and 67.6% of the subjects were female. Sixteen subjects met the DSM-IV criteria for delirium, 7 met the diagnostic criteria
38
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40 Table 2 Sensitivity and Specificity of the Japanese version of MDAS (n ⫽ 37)
Table 1 Demographic Characteristics of 36 Elderly Subjects Diagnostic group
N
Sex female
Age mean (SD)
PS mean (SD)
Delirium Dementia Mood Disorders Schizophrenia
16 7 10 3
8 4 9 3
77.44 (5.35)a 77.43 (4.31)a 70.40 (7.86)a 72.33 (5.31)a
2.69 (0.92)b 0.43 (0.50)b,c 0.10 (0.30)b,c 0.00 (0.00)b,c
a
P⬍0.05 by one way ANOVA P⬍0.00001 by one way ANOVA c P⬍0.00001 by Scheffe’s test (vs. Delirium) PS: Performance Status (Eastern Cooperative Oncology Group’s Scale) b
for dementia (4 for Alzheimer-type dementia and 3 for vascular dementia), 10 had mood disorders (5 with major depressive disorder, 2 with bipolar I disorder, and 3 with dysthymic disorder), and 3 had schizophrenia, and 1 had a conversion disorder. The subjects were organized into groups: delirium, dementia, mood disorders, and schizophrenia. The one patient with the conversion disorder was not assigned to a group. Demographic information about the four groups is shown in Table 1. The average age differed significantly among the four groups [F⫽3.05, df⫽3, 32, P⫽.043]. The patients with delirium had poorer performance status (measured by the Eastern Cooperative Oncology Group’s Scale) than the other three groups. The MDAS score differed significantly among the four groups [F⫽51.44, df⫽3, 32, P⬍.00001]. The average MDAS scores were 18.31 (SD⫽4.25) for the patients with delirium, 6.14 (SD⫽2.10) for the patients with dementia, 3.80 (SD⫽2.04) for the patients with mood disorders, and 2.33 (SD⫽0.94) for the patients with schizophrenia. Posthoc contrast analyses (Scheffe’s test) demonstrated that patients with delirium had significant higher MDAS scores than those of the patients with dementia (F⫽21.10, df⫽3, 32, P⬍.00001), the patients with mood disorders (F⫽37.92, df⫽3, 32, P⬍.00001), and the patients with schizophrenia (F⫽18.87, df⫽3, 32, P⬍.00001). There was no significant difference in MDAS scores between patients with dementia
Cutoff score
Sensitivity
Specificity
7 8 9 10 11 12 13
1.00 1.00 1.00 1.00 1.00 1.00 0.94
0.81 0.91 0.95 1.00 1.00 1.00 1.00
and patients with mood disorders (F⫽0.66, df⫽3, 32, P⫽NS) or schizophrenia (F⫽0.89, df⫽3, 32, P⫽NS). Average scores on the MMS and DRS assessments differed significantly among the four groups by one-way ANOVA (P⬍.00001). There was a significant difference in MMS scores between patients with delirium and those patients with mood disorders [F⫽22.83, df⫽3, 32, P⬍.00001] or schizophrenia [F⫽8.07, df⫽3, 32, P⫽.00038]. There was also a significant difference in DRS scores between patients with delirium and those patients with dementia [F⫽79.09, df⫽3, 32, P⬍.00001], mood disorders [F⫽117.34, df⫽3, 32, P⬍.00001] or schizophrenia [F⫽55.01, df⫽3, 32, P⬍.00001]. The MDAS cutoff diagnostic scores with relevant sensitivities and specificities are summarized in Table 2. A diagnostic cutoff score of 10 gave optimum results in relation to the presence or absence of delirium. 3.2. Reliability and validity testing Correlational analyses revealed an overall Cronbach’s alpha coefficient of 0.92 based on the MDAS ratings of the principal investigator (Y.M.). The item-total correlations for the ten items ranged from 0.62 to 0.92. The individual item-total correlations and intraclass correlation coefficients are detailed in Table 3. The overall correlation coefficient for the two psychiatrists’ ratings, calculated for the entire
Table 3 Japanese version of Memorial Delirium Assessment Scale Reliability Data MDAS item
Mean
SD
Alpha if removed
Item-total r
Intra-class r
1 2 3 4 5 6 7 8 9 10
0.78 1.62 1.54 1.11 0.84 0.73 0.73 0.76 1.19 1.05
1.00 1.36 0.80 1.13 1.07 0.96 1.07 0.90 1.13 0.78
0.90 0.92 0.92 0.91 0.90 0.90 0.91 0.92 0.91 0.91
0.91 0.65 0.63 0.75 0.92 0.89 0.75 0.62 0.78 0.76
0.90 0.99 0.96 1.00 0.86 0.87 0.93 0.85 0.91 0.92
Y. Matsuoka et al. / General Hospital Psychiatry 23 (2001) 36 – 40
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scale, was 0.98. Individual items varied in reliability between raters; the intraclass correlation coefficients ranged from 0.85 to 1.00 (Table 3). In addition, correlational analyses revealed an overall Cronbach’s alpha coefficient of 0.94 based on the DRS ratings of the principal investigator (Y.M.). The item-total correlations for the ten items ranged from 0.65 to 0.95. The scores on the MDAS assessments correlated fairly well with scores on the CGR assessment (r⫽.67, P⫽.0047), the DRS assessment (r⫽.73, P⫽.0011) and the MMS assessment (r⫽⫺.54 P⫽.029).
lation and a high reliability coefficient between raters in our study. This difference signifies that in our study, we investigated patients before they had received any treatment for delirium, while Breitbart et al. investigated patients that had already received some degree of treatment for delirium. [4]. Correlation between CGR and MDAS scores, DRS and MDAS, MMS and MDAS were lower in our study than that of Breitbart et al. (r⫽.67 and 0.89, r⫽.73 and 0.88, r⫽⫺.54 and– 0.91, respectively). The sample used to test concurrent validity in this present study was very small and further study is needed.
4. Discussion
4.1. Clinical implications and limitations
The present results indicate that the Japanese version of the MDAS has acceptable reliability and that this scale is a useful tool for assessing delirium among psycho-geriatric populations. The ten-item MDAS has a high degree of internal consistency, a high level of reliability between two rating psychiatrists and fair degree of concurrent validity with other measures of delirium and delirium severity. Although the MDAS was developed as an instrument for assessing the severity of delirium symptoms, rather than as a diagnostic tool, our results suggest that the MDAS may also be a useful tool for establishing a diagnosis of delirium. The MDAS significantly differentiated between patients with delirium and patients with dementia or noncognitive psychiatric disorders using a cutoff score of 10. Breitbart et al. reported an optimum MDAS diagnostic cutoff score of 13 in the original MDAS validation study [4]. Breitbart et al. acknowledged the potential limitations of the MDAS as a diagnostic instrument, especially in the case of mild delirium [4]. Lawlor et al. suggested an optimum MDAS diagnostic cutoff score of 7 in a further MDAS validation study [5]. Lawlor et al. mentioned its potential to capture a greater population of milder episodes of delirium [5]. However they investigated milder delirium than our study. We suggested that selection of delirium referrals to a psychiatric service, as in the original MDAS validation study [4], could lead to selection bias in favor of more severe delirium than our study. Our study suggests that a nonpsychiatric clinician treated most of the patients with mild to moderate delirium, so only selected patients with moderate to severe delirium were also referred to our department. At any rate, we found that the MDAS was a helpful tool to distinguish delirium from other psychiatric disorders in the psychogeriatric unit setting. Further research with larger, more diverse populations of patients in various clinical settings may also be helpful in determining the most appropriate cutoff score. Although two of the ten MDAS items (items 7 and 8, measuring hallucinations and delusions) were less highly correlated with the overall MDAS score in previous study [4], all ten of the MDAS items had a high item-total corre-
The Japanese version of MDAS is a reliable instrument that measures delirium severity in the elderly. The MDAS appeared to differentiate between patients with delirium and patients with dementia or noncognitive psychiatric disorders using a cutoff score of 10. Since we conducted this study in a clinical context with limited manpower, our study has the limitation of having a modest sample size. Though there are clearly cultural differences between the West and Asia, there is no evidence nor any reason to believes that the expression of delirium differs in different countries. Indeed, the fact that a Western-developed delirium assessment tool could be translated and applied successfully in Japan argues for the generalizability of these reasons to other countries. We hope that further research with this instrument in different clinical settings including a geriatric population in various countries will be performed. Therefore we are now planning the clinical research using the Japanese version of MDAS.
Acknowledgments The authors would like to thank Dr. William Breitbart, Department of Psychiatry, Memorial Sloan-Kettering Cancer Center, for his permission and advice in the translation of MDAS into Japanese. We also thank Dr. Motoko Kondo for her great help with a back-translation of the MDAS, Sister Sabina Sausam at the St. John’s Society Nunnery for language revision and linguistic advice, Dr. Marcus Wenner at Psycho-Oncology Division, National Cancer Center Research Institute East, for kind-hearted comments, and the two anonymous referees for helpful comments on earlier drafts.
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