Replication analysis for composition of the Delirium Motor Subtype Scale (DMSS) in a referral cohort from Northern India

Does the Etiology, Phenomenology and Motor Subtype of Delirium Differ When It Occurs in Patients With An Underlying Dementia?: A Multi-Site, International Study

OBJECTIVES

To compare the etiology, phenomenology and motor subtype of delirium in patients with and without an underlying dementia.

METHODS

A combined dataset (n = 992) was collated from two databases of older adults (>65 years) from liaison psychiatry and palliative care populations in Ireland and India. Phenomenology and severity of delirium were analysed using the Delirium Symptom Rating Scale Revised (DRS-R98) and contributory etiologies for the delirium groups were ascertained using the Delirium Etiology Checklist (DEC). Delirium motor subtype was documented using the abbreviated version of the Delirium Motor Subtype Scale (DMSS4).

RESULTS

Delirium superimposed on dementia (DSD) showed greater impairment in short term memory, long term memory and visuospatial ability than the delirium group but showed significantly less perceptual disturbance, temporal onset and fluctuation. Systemic infection, cerebrovascular and other Central nervous system etiology were associated with DSD while metabolic disturbance, organ insufficiency and intracranial neoplasm were associated with the delirium only group.

CONCLUSION

The etiology and phenomenology of delirium differs when it occurs in the patient with an underlying dementia. We discuss the implications in terms of identification and management of this complex condition.

How do delirium motor subtypes differ in phenomenology and contributory aetiology? a cross-sectional, multisite study of liaison psychiatry and palliative care patients

OBJECTIVES

To investigate whether delirium motor subtypes differ in terms of phenomenology and contributory aetiology.

DESIGN

Cross-sectional study.

SETTING

International study incorporating data from Ireland and India across palliative care, old age liaison psychiatry and general adult liaison psychiatry settings.

PARTICIPANTS

1757 patients diagnosed with delirium using criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth edition (DSM IV).

PRIMARY AND SECONDARY OUTCOME MEASURES

Hyperactive, mixed and hypoactive delirium subtypes were identified using the abbreviated version of the Delirium Motor Subtype Scale. Phenomenology was assessed using the Delirium Rating Scale Revised. Contributory aetiologies were assessed using the Delirium Aetiology Checklist (DEC), with a score >2 indicating that the aetiology was likely or definitely contributory.

RESULTS

Hypoactive delirium was associated with dementia, cerebrovascular and systemic infection aetiologies (p<0.001) and had a lower overall burden of delirium symptoms than the other motor subtypes. Hyperactive delirium was associated with younger age, drug withdrawal and the DEC category other systemic aetiologies (p<0.001). Mixed delirium showed the greatest symptom burden and was more often associated with drug intoxication and metabolic disturbance (p<0.001). All three delirium motor subtypes had similar levels of impairment in attention and visuospatial functioning but differed significantly when compared with no subtype (p<0.001).

CONCLUSIONS

This study indicates a pattern of aetiology and symptomatology of delirium motor subtypes across a large international sample that had previously been lacking. It serves to improve our understanding of this complex condition and has implications in terms of early detection and management of delirium.

Delirium Research in India: A Systematic Review

Delirium is the most common psychiatric diagnoses encountered in patients with various medical-surgical illnesses, in all the treatment set-ups, with relatively higher incidence and prevalence in the intensive care units. As delirium is encountered in multiple specialties, it is important to understand the research on this diagnosis. This study aims to assess the research output involving patients of delirium from India. A comprehensive search was undertaken using Medline (PubMed) and other databases. Search words included were “delirium,” “delirious,” “delirium tremens” AND “India.” No filters were used. Internet and hand searches yielded 305 articles. Out of these articles, 151 had the terms “delirium,” “delirious,” “delirium tremens” in the title and these were included for the review. Additionally, 14 articles were included for the review, although these did not have these terms in the title, but delirium was one of the major outcome parameters in these studies. Majority of the papers were original articles ( n = 81), and these were followed by, case reports ( n = 58), review articles ( n = 10), letter to the editor (not as case reports but as a communication; n = 13), editorials ( n = 2) and one clinical practice guideline. Most of the original papers have either focused on epidemiology (incidence, prevalence, outcome, etc.), symptom profile, with occasional studies focusing on effectiveness of various pharmacological interventions. There is a dearth of research in the field of delirium from India. There is a lack of studies on biomarkers, evaluation of nonpharmacological interventions, and evaluation of prevention strategies. It is the need of the hour to carry out more studies to further our understanding of delirium in the Indian context.

Delirium clinical motor subtypes: a narrative review of the literature and insights from neurobiology

INTRODUCTION

Clinical motor subtypes have been long recognised in delirium and, despite a growing body of research, a lack of clarity exists regarding the importance of these motor subtypes. The aims of this review are to (1) examine how the concept of motor subtypes has evolved, (2) explore their relationship to the clinical context, (3) discuss the relationship between the phenomenology of delirium and motor activity, (4) discuss the application of neurobiology to the theory of delirium motor subtypes, and (5) identify methodological issues and provide solutions for further studies.

METHODS

The following databases were searched: PubMed, PsychInfo, EBSCO, Medline, BioMed central and Science Direct. Inclusion criteria specified peer-reviewed research assessing delirium motor subtypes published between 1990 and 2016.

RESULTS

Sixty-one studies met the inclusion criteria. The majority of studies (n = 50) were found to use validated psychometric tools, while the remainder (n = 11) used clinical criteria. The majority of studies (n = 45) were conducted in the medical setting, while the remainder were in the ICU/post-operative setting (n = 17).

CONCLUSION

Although host sensitivities (e.g. frailty) and exogenous factors (e.g. medication exposure) may determine the type of motor disturbance, it remains unclear to what extent motor subtypes are influenced by other features of delirium. The use of more specialised tools (e.g. delirium motor subtyping scale), may enable researchers to develop an approach to delirium that has a greater nosological consistency. Future studies investigating delirium motor subtypes may benefit from enhanced theoretical considerations of the dysfunctional neural substrate of the delirious state.

Delirium in Intensive Care Unit: Phenomenology, Subtypes, and Factor Structure of Symptoms

AIM

This study aimed to explore the phenomenology, motor subtypes, and factor structure of symptom profile of delirium in patients admitted to the intensive care unit (ICU).

METHODS

Consecutive patients aged ≥16 years admitted in an ICU were screened daily for delirium using confusion assessment method-ICU. Patients diagnosed to have delirium as per Diagnostic and Statistical Manual fourth revision, text revision (DSM-IVTR) criteria were assessed with Delirium Rating Scale-Revised 98 (DRS-R 98) and Memorial Delirium Assessment Scale (MDAS). Motor subtypes of delirium were assessed with amended Delirium Motor Symptom Scale.

RESULTS

Sixty-six patients were evaluated for delirium, of which 45 (68%) patients developed delirium at point of their ICU stay. All patients had sleep-wake cycle disturbances, followed by motor symptoms (retardation - 80%; agitation - 73.3%). As per MDAS assessment, all the subjects had disturbances in the consciousness and sleep-wake cycle disturbances, and a substantial majority also had attention difficulties (93.3%) and motor symptoms (93.3%). Hypoactive subtype (47%) was the most common motoric subtype of delirium. Factor analysis revealed three-factor model for DRS-R 98, MDAS, and combining items of the two.

CONCLUSION

Phenomenology of delirium in ICU setting is similar to that of the non-ICU settings. The factor analysis consistently demonstrated a three factor solution, with a robust attention-arousal factor, and overlapping cognitive (core vs. non-core) motor factors.

Validation of the Korean Version of the Delirium Motor Subtype Scale

OBJECTIVE

The Delirium Motor Subtype Scale (DMSS) is a validated and reliable instrument developed from various methods previously used to assess delirium motor subtypes. It focuses on pure motor disturbances with a relative specificity for delirium. The aim of this study was to investigate the validity and reliability of a Korean version of the DMSS (K-DMSS).

METHODS

We recruited 145 patients who were older than 60 years and had been referred for psychiatric consultation for delirium. These patients were evaluated using the K-DMSS, Liptzin & Levkoff criteria, and the Korean version of the Delirium Rating Scale-Revised-98 (K-DRS-R98) to compare delirium motor subtypes.

RESULTS

The internal consistency of the K-DMSS in assessing delirium motor subtypes was acceptable (Cronbach's alpha=0.79). Delirium motor subtypes identified with the K-DMSS and K-DRS-R98 showed almost perfect agreement (Cohen's Kappa=0.81), while those identified with the K-DMSS and Liptzin & Levkoff criteria showed substantial agreement (Cohen's Kappa=0.78).

CONCLUSION

Our results suggest that the K-DMSS is a valid and reliable tool for identifying delirium subtypes.

Validation and Psychometric Properties of the German Version of the Delirium Motor Subtype Scale (DMSS)

Objective: Delirium has been characterized into its subtypes—hypoactive, hyperactive, mixed, or no motor subtype—along with the use of the Delirium Motor Symptom Scale (DMSS). The German version of this scale (DMSS-G), however, has not yet been validated. Method: We determined internal consistency, reliability, and validity of the DMSS-G in the surgical intensive care unit, using DSM-IV-TR criteria and the Delirium Rating Scale–Revised–98. Results: In total, 289 patients were included, and out of these, 122 were delirious. The DMSS-G showed excellent internal consistency (Cronbach’s α = 0.92) and interrater reliability (Fleiss κ = 0.83). Additionally, the overall concurrent validity was substantial (Cramer’s V = 0.69); within subtypes, hyperactive, hypoactive, or mixed, the concurrent validity remained at least substantial (Cohen’s κ = 0.73-0.82) and the sensitivity ranged from 60% to 97%. In contrast, in those with no motor subtype, we found the concurrent validity (Cohen’s κ = 0.31) and sensitivity to be low (22%). Overall, specificity for all individual subtypes was high (82% to 100%). The DMSS was very sensitive in both rating hyperactive and hypoactive motor symptoms of delirium. Conclusion: The DMSS-G is a highly reliable and valid instrument for detecting motor symptoms in delirium, which provides an accurate instrument to classify the motor subtypes of delirium.

Brief assessment of delirium subtypes: Psychometric evaluation of the Delirium Motor Subtype Scale (DMSS)-4 in the intensive care setting

OBJECTIVE

The management of and prognosis for delirium are affected by its subtype: hypoactive, hyperactive, mixed, and none. The DMSS-4, an abbreviated version of the Delirium Motor Symptom Scale, is a brief instrument for the assessment of delirium subtypes. However, it has not yet been evaluated in an intensive care setting.

METHOD

We performed a prospective/descriptive cohort study in order to determine the internal consistency, reliability, and validity of the relevant items of the DMSS-4 versus the Delirium Rating Scale-Revised-98 (DRS-R-98) and the original DMSS in a surgical intensive care setting.

RESULTS

A total of 289 elderly, predominantly male patients were screened for delirium, and 122 were included in our sample. The internal consistency of the DMSS-4 items was excellent (Cronbach's α = 0.92), and between the DMSS-4 and DRS-R-98 the overall concurrent validity was substantial (Cramer's V = 0.67). Within individual motor subtypes, concurrent validity remained at least substantial (Cohen's κ = 0.65-0.81) and sensitivity high (69.8 to 82.2%), in contrast to those of the no-motor subtype, with less validity and sensitivity (κ = 0.28, 22%). Similarly, total concurrent validity between the DMSS-4 and the original DMSS reached perfection (Cramer's V = 0.83), as did agreement between the subtypes (κ = 0.83-0.92), while sensitivity remained high (88.2-100%). Only in those with delirium with no-motor subtype was agreement moderate (κ = 0.56) and sensitivity lower (67%). Specificity was high across all subtypes (91.2-99.1%). The DMSS-4 yielded very sensitive ratings, particularly for hypoactive and hyperactive motor symptoms, and interrater agreement was excellent (Fleiss's κ = 0.83).

SIGNIFICANCE OF RESULTS

We found the DMSS-4 to be a most reliable and valid brief assessment of delirium in characterizing the subtypes of delirium in an intensive care setting, with increased sensitivity to hypoactive and hyperactive motor alterations.

Phenomenology of delirium among patients admitted to a coronary care unit

AIM

To study the phenomenology and motor sub-types of delirium in patients admitted in a Coronary Care Unit (CCU).

METHODS

Three hundred and nine consecutive patients were screened for delirium, and those found positive for the same were evaluated by a psychiatrist on DSM-IVTR criteria to confirm the diagnosis. Those with a diagnosis of delirium were evaluated on the DRS-R-98 to study the phenomenology and on the amended Delirium Motor Symptom Scale (DMSS) to study the motor sub-types.

RESULTS

Eighty-one patients were found to have delirium. Commonly seen symptoms of delirium included: disturbances in sleep-wake cycle, lability of affect, thought abnormality, disturbance in attention, disorientation, short-term memory, and long-term memory. Very few patients had delusions. More than half of the participants were categorized as having hyperactive (n = 46; 56.8%) followed by hypoactive sub-type (n = 21; 26%) and mixed sub-type (n = 9; 11.1%) of delirium. There were minor differences in the frequency and severity of symptoms of delirium between incidence and prevalence cases of delirium and those with different motoric sub-types.

CONCLUSION

Delirium in CCU set-up is characterized by the symptoms of disturbances in sleep-wake cycle, lability of affect, thought abnormality, disturbance in attention, disorientation, short-term memory, and long-term memory. Hyperactive delirium is more common than hypoactive delirium.

Comparative effectiveness of quetiapine and haloperidol in delirium: A single blind randomized controlled study

AIM

To evaluate the effectiveness of quetiapine and haloperidol in patients of delirium referred to psychiatry consultation liaison services.

METHODS

The study followed a single blind randomised controlled trial design. Thirty-two patients in the haloperidol group and 31 patients in the quetiapine group were assessed at the baseline and 6 consecutive days. Flexible dosing regimen (haloperidol: 0.25-1.25 mg; quetiapine 12.5-75 mg/d) was used. Delirium Rating Scale-Revised-98 (DRS-R-98) and mini mental status examination (MMSE) were the primary and secondary efficacy measures respectively.

RESULTS

Baseline DRS-R-98 severity score and MMSE scores did not differ between the 2 study groups. From baseline to day 6, there was significant reduction in the total DRS-R-98 scores, DRS-R-98 cognitive domain scores, DRS-R-98 non-cognitive domain scores and significant increase in the MMSE scores in both the groups. Both the groups did not differ on any of the assessments in terms of DRS-R98 and MMSE scores. The effectiveness of both the medications was similar in adult and elderly (≥ 60 years) patients. At the end of the trial, 68.75% and 67.74% of subjects in the haloperidol and quetiapine group respectively had mean DRS-R-98 scores below 10. By 6^th day, 12 (37.5%) patients in haloperidol group and 9 (29.03%) patients in the quetiapine group had DRS-R98 score of “0” with no significant difference between the two groups (P = 0.47).

CONCLUSION

Quetiapine is as effective as haloperidol in the management of delirium.

Psychometric evaluation of the DMSS-4 in a cohort of elderly post-operative hip fracture patients with delirium

BACKGROUND

Delirium is a common neuropsychiatric syndrome with considerable heterogeneity in clinical profile. Rapid reliable identification of clinical subtypes can allow for more targeted research efforts.

METHODS

We explored the concordance in attribution of motor subtypes between the Delirium Motor Subtyping Scale 4 (DMSS-4) and the original Delirium Motor Subtyping Scale (DMSS) (assessed cross-sectionally) and subtypes defined longitudinally using the Delirium Symptom Interview (DSI).

RESULTS

We included 113 elderly patients developing DSM-IV delirium after hip-surgery [mean age 86.9 ± 6.6 years; range 65-102; 68.1% females; 25 (22.1%) had no previous history of cognitive impairment]. Concordance for the first measurement was high for both the DMSS-4 and original DMSS (k = 0.82), and overall for the DMSS-4 and DSI (k = 0.84). The DMSS-4 also demonstrated high internal consistency (McDonald's omega = 0.90). The DSI more often allocated an assessment to "no subtype" compared to the DMSS-4 and DMSS-11, which showed higher inclusion rates for motor subtypes.

CONCLUSIONS

The DMSS-4 provides a rapid method of identifying motor-defined clinical subtypes of delirium and appears to be a reliable alternative to the more detailed and time-consuming original DMSS and DSI methods of subtype attribution. The DMSS-4, so far translated into three languages, can be readily applied to further studies of causation, treatment and outcome in delirium.

Prevalence, course and factors associated with delirium in elderly patients with advanced cancer: a longitudinal observational study

OBJECTIVE

The aim of this study was to investigate the prevalence of delirium on admission, the course of delirium during a 2-week period after admission and factors associated with delirium on admission, among elderly patients with advanced cancer.

METHODS

Patients aged ≥ 65 years with incurable lung or gastroenterological cancer and the Eastern Cooperative Oncology Group Performance Status 2 or greater were continuously sampled after admission to a university hospital. Participants were evaluated for DSM-IV-TR delirium by trained psychiatrists and the delirium subtype was assessed using the Delirium Motor Subtype Scale within 4 days after admission and again 2 weeks later. In addition, we assessed associated factors with delirium on admission.

RESULTS

Among 73 eligible patients, complete data were available from 61 on admission and 49 after 2 weeks. Twenty-six patients (43%) met delirium criteria on admission (hypoactive: 58%, unspecified: 35%, hyperactive: 4%, mixed: 4%). Of these, 19 (73%) remained delirious 2 weeks later. Of 35 patients without delirium on admission, 21 (60%) remained delirium-free 2 weeks later and 7(20%) became delirious. Overall, 33/61 (54%) developed delirium at some point during the study. Patients receiving steroids at admission were more likely to have delirium (odds ratio = 5.0; 95% confidence interval = 1.5-16).

CONCLUSIONS

Given the high prevalence of the delirium, all patients with advanced cancer should be screened for delirium both on admission and regularly thereafter. In addition, medical staff should be aware that steroid use on admission is an additional indicator of elevated risk for delirium.

MMSE items that predict incident delirium and hypoactive subtype in older medical inpatients

Because hypoactive delirium is especially under-recognized, we analyzed which Mini-Mental State Examination (MMSE) items predicted incident delirium and its hypoactive motor presentation. Over a 1-year period, older medical inpatients (n=291) were consecutively screened on admission with the Confusion Assessment Method-Spanish (CAM-S) to exclude prevalent delirium. Nondelirious patients were evaluated the same day with the MMSE, followed by daily ratings with the CAM-S. Those who became CAM-S positive were rated using the Delirium Rating Scale-Revised-98 to assess severity and motor subtype. Disorientation to time (OR 4.4, 95% CI 1.7-11.1) and place (OR 3.8, 95% CI 1.7-8.2) at admission were risk factors for delirium at follow-up and together correctly classified 88.3% of subjects as to delirium status. Disorientation to time and place, and visuoconstructional impairment were each associated with either hypoactive or mixed subtype (p<0.05 χ(2) test). Simple bedside evaluation of cognitive function in nondelirious patients revealed deficits that detected patients at risk for developing incident delirium at follow-up (especially hypoactive or mixed). We recommend patients with orientation deficits be monitored closely for emergence of delirium. A separate evaluation for possible dementia or other causes of cognitive impairment at admission should be considered too.

Concordance between DSM-IV and DSM-5 criteria for delirium diagnosis in a pooled database of 768 prospectively evaluated patients using the delirium rating scale-revised-98

BACKGROUND

The Diagnostic and Statistical Manual fifth edition (DSM-5) provides new criteria for delirium diagnosis. We examined delirium diagnosis using these new criteria compared with the Diagnostic and Statistical Manual fourth edition (DSM-IV) in a large dataset of patients assessed for delirium and related presentations.

METHODS

Patient data (n = 768) from six prospectively collected cohorts, clinically assessed using DSM-IV and the Delirium Rating Scale-Revised-98 (DRS-R98), were pooled. Post hoc application of DRS-R98 item scores were used to rate DSM-5 criteria. 'Strict' and 'relaxed' DSM-5 criteria to ascertain delirium were compared to rates determined by DSM-IV.

RESULTS

Using DSM-IV by clinical assessment, delirium was found in 510/768 patients (66%). Strict DSM-5 criteria categorized 158 as delirious including 155 (30%) with DSM-IV delirium, whereas relaxed DSM-5 criteria identified 466 as delirious, including 455 (89%) diagnosed by DSM-IV (P <0.001). The concordance between the different diagnostic methods was: 53% (ĸ = 0.22) between DSM-IV and the strict DSM-5, 91% (ĸ = 0.82) between the DSM-IV and relaxed DSM-5 criteria and 60% (ĸ = 0.29) between the strict versus relaxed DSM-5 criteria. Only 155 cases were identified as delirium by all three approaches. The 55 (11%) patients with DSM-IV delirium who were not rated as delirious by relaxed criteria had lower mean DRS-R98 total scores than those rated as delirious (13.7 ± 3.9 versus 23.7 ± 6.0; P <0.001). Conversely, mean DRS-R98 score (21.1 ± 6.4) for the 70% not rated as delirious by strict DSM-5 criteria was consistent with suggested cutoff scores for full syndromal delirium. Only 11 cases met DSM-5 criteria that were not deemed to have DSM-IV delirium.

CONCLUSIONS

The concordance between DSM-IV and the new DSM-5 delirium criteria varies considerably depending on the interpretation of criteria. Overly-strict adherence for some new text details in DSM-5 criteria would reduce the number of delirium cases diagnosed; however, a more 'relaxed' approach renders DSM-5 criteria comparable to DSM-IV with minimal impact on their actual application and is thus recommended.

Do patients of delirium have catatonic features? An exploratory study

AIM

The aim of this study was to determine the prevalence of catatonic symptoms, as per the Bush Francis Catatonia Rating Scale (BFCRS), in patients with delirium and to evaluate the prevalence of catatonia as defined by the Bush Francis Catatonia Screening Instrument and DSM-5 criteria in patients with delirium.

METHOD

Two hundred five consecutive subjects with delirium were assessed on the Delirium Rating Scale-Revised 98 version, the amended Delirium Motor Symptom Scale and the BFCRS.

RESULTS

On the BFCRS, two-fifths (n = 80; 39%) of the study participants had two or more catatonic symptoms. When the diagnosis of catatonic syndrome was considered, 32% and 12.7% were observed to have catatonia as per the Bush Francis Catatonia Screening Instrument and proposed DSM-5 criteria, respectively. Delirium with catatonic syndrome was more common in women and in those who had onset of delirium prior to hospitalization. Amongst the delirium subtypes, hypoactive delirium was more commonly associated with catatonic syndrome.

CONCLUSION

The present study suggests that a substantial number of patients with delirium have catatonic symptoms and a significant proportion have catatonic syndrome. This high prevalence makes the concurrent diagnosis of delirium and catatonia plausible. The association of catatonia with a specific motor subtype of delirium could encourage the expansion or even modification of the existing subtypes of delirium.

Comparison of symptoms of delirium across various motoric subtypes

AIM

The aim of this study was to determine the correlation between delirium motor subtypes and other symptoms of delirium.

METHODS

Three hundred and twenty-one (n = 321) consecutive patients referred to consultation-liaison psychiatry services were evaluated on Delirium Rating scale-Revised-98 version and amended Delirium Motor Symptom Scale.

RESULTS

Half of the patients had hyperactive subtype (n = 161; 50.15%) delirium. One-quarter of the study sample met the criteria for mixed subtype (n = 79; 24.61%), about one-fifth of the study sample met the criteria for hypoactive delirium subtype (n = 64; 19.93%), and only very few patients (n = 17; 5.29%) did not meet the required criteria for any of these three subtypes and were categorized as 'no subtype'. When the hyperactive and hypoactive subtypes were compared, significant differences were seen in the prevalence of perceptual disturbances, delusions, lability of affect, thought process abnormality, motor agitation and motor retardation. All the symptoms were more common in the hyperactive subtype except for thought process abnormality and motor retardation. Compared to hyperactive subtype, the mixed subtype had significantly higher prevalence of thought process abnormality and motor retardation. Significant differences emerged with regard to perceptual disturbances, delusions, lability of affect and motor agitation when comparing the patients with mixed subtype with those with hypoactive subtype. All these symptoms were found to be more common in the mixed subtype. No significant differences emerged for the cognitive symptoms as assessed on Delirium Rating scale-Revised-98 across the different motoric subtypes.

CONCLUSION

Different motoric subtypes of delirium differ on non-cognitive symptoms.

Development of an abbreviated version of the delirium motor subtyping scale (DMSS-4)

BACKGROUND

Delirium is a common neuropsychiatric syndrome with considerable heterogeneity in clinical profile. Identification of clinical subtypes can allow for more targeted clinical and research efforts. We sought to develop a brief method for clinical subtyping in clinical and research settings.

METHODS

A multi-site database, including motor symptom assessments conducted in 487 patients from palliative care, adult and old age consultation-liaison psychiatry services was used to document motor activity disturbances as per the Delirium Motor Checklist (DMC). Latent class analysis (LCA) was used to identify the class structure underpinning DMC data and also items for a brief subtyping scale. The concordance of the abbreviated scale was then compared with the original Delirium Motor Subtype Scale (DMSS) in 375 patients having delirium as per the American Psychiatric Association's Diagnostic and Statistical Manual (4th edition) criteria.

RESULTS

Latent class analysis identified four classes that corresponded closely with the four recognized motor subtypes of delirium. Further, LCA of items (n = 15) that loaded >60% to the model identified four features that reliably identified the classes/subtypes, and these were combined as a brief motor subtyping scale (DMSS-4). There was good concordance for subtype attribution between the original DMSS and the DMSS-4 (κ = 0.63).

CONCLUSIONS

The DMSS-4 allows for rapid assessment of clinical subtypes in delirium and has high concordance with the longer and well-validated DMSS. More consistent clinical subtyping in delirium can facilitate better delirium management and more focused research effort.