Validating a new clinical subtyping scheme for delirium with electronic motion analysis Alan Godfrey a , Maeve Leonard b,c,d , Sinead Donnelly d , Marion Conroy d , Gearóid ÓLaighin e , David Meagher b,c,d, ⁎ a Biomedical Electronics Laboratory, Department of Electronic and Computer Engineering, University of Limerick, Ireland b Department of Psychiatry, Midwestern Regional Hospital, Limerick, Ireland c Health Systems Research Centre, University of Limerick, Ireland d Milford Hospice Palliative Care Centre, Castletroy, Limerick, Ireland e Department of Electronic Engineering and National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland abstract article info Article history: Received 26 June 2008 Received in revised form 23 March 2009 Accepted 15 April 2009 Keywords: Delirium Accelerometry Motor activity Subtypes The usefulness of motor subtypes of delirium is unclear due to inconsistency in sub-typing methods and a lack of validation with objective measures of activity. The activity of 40 patients was measured with 24 h accelerometry monitoring. Patients with Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) delirium (n =30) were allocated into hyperactive, hypoactive and mixed motor subtypes. Delirium subtypes differed in relation to overall amount of activity, including movement in both sagittal and transverse planes. Differences were greater in the daytime and during the early evening ‘sundowning’ period. Frequency of postural changes was the most discriminating measure examined. Clinical subtypes of delirium defined by observed motor behaviour on the ward differ in electronically measured activity levels. © 2009 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Delirium is the umbrella term applied in both Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV) (American Psychiatric Association, 2000) and the International Classifica- tion of Diseases (ICD) (World Health Organization, 1992) to denote acute generalised disturbances of cognitive function and reflects a complex neuropsychiatric syndrome that is highly heterogenous in causation and clinical presentation. Since ancient times a number of contrasting clinical presentations have been described including a relatively hyperactive/ agitated form ‘ phrenitis’ as well as a more hypoactive and quiet variant, ‘ lethargicus’ (Bynum, 2000). More recently, Lipowski (1989) described hypoactive, hyperactive, and mixed motor subtypes and subsequently a variety of approaches to motor subtype definition have been described (Liptzin and Levkoff, 1992; Breitbart et al., 1997; O'Keeffe and Lavan, 1999; Meagher et al., 2008a). Clinically defined subtypes can promote a better understanding of delirium by allowing more targeted studies of pathophysiology and treatment. Studies indicate significant differences between motor subtypes in relation to severity of non-motor symptoms (Meagher et al., 2000), detection (Inouye, 1994), aetiology (Meagher et al., 1998), pathophysiology (Balan et al., 2003; Van der Cammen et al., 2006), treatment experience (Meagher et al., 1996; Marcantonio et al., 2002; Breitbart et al., 2002) and prognosis (Marcantonio et al., 2002; Olofsson et al., 1996). However, these studies are fraught with methodological inconsistencies, especially regarding motor subtype definition. Concor- dance among four commonly used sub-typing schemes was only 34% in a recent study where focus on ‘ pure’ motor disturbances along with objective electronic motion analysis were identified as ways to develop methods with improved reliability and validity (Meagher et al., 2008b). Preliminary work has explored the applicability of accelerometer-based monitoring in patients with delirium (Leonard et al., 2007). Meagher et al. (2008a) developed a subtyping scheme derived from items in previous checklists where subtype criteria have (i) relative specificity for delirium compared with non-delirious comparison subjects and (ii) correlate with an independent observation of motion. The specific aims of this study were to (a) validate this new method of defining motor subtypes of delirium by examining whether electronic measures of motion distinguish these groups, (b) assess the relative usefulness of a range of measures of motion (movement in different planes, of various durations and postural changes) in distinguishing subtypes, including profile over 24 h and (c) compare the motor activity profile of delirious patients with non-delirious comparison subjects. 2. Method This study was conducted at Milford Hospice Palliative Care Centre in Limerick, Ireland. Consecutive admissions to the palliative care unit with evidence of DSM IV delirium were asked to participate until 30 participants were identified. In addition 10 non-delirious control subjects were included for accelerometry monitoring. Clinical assessments to rate delirium phenomenology and severity, assesses medical morbidity and aetiology and define motor subtypes were performed at the end of the Psychiatry Research 178 (2010) 186–190 ⁎ Corresponding author. Department of Adult Psychiatry, Midwestern Regional Hospital, Limerick, Ireland. Tel.: +353 872333616. E-mail address: david.meagher@ul.ie (D. Meagher). 0165-1781/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2009.04.010 Contents lists available at ScienceDirect Psychiatry Research journal homepage: www.elsevier.com/locate/psychres