039 FREQUENCY AND STABILITY OF MOTOR SUBTYPES IN OLDER MEDICAL INPATIENTS WITH INCIDENT DELIRIUM

Background Delirium is highly prevalent, and serious, yet remains under-recognised. Although patients presenting with hypoactivity have the worst prognosis, they are most commonly missed or misdiagnosed. Most studies of motor profile have been conducted using cross-sectional methodology, however longitudinal studies are required to truly understand motor course, given the dynamic nature of delirium. Older patients are particularly vulnerable to delirium, however little is known about motor profile in this group. We aimed to investigate the frequency and stability of motor subtypes in incident delirium in older medical inpatients. Methods Medical inpatients of ≥70 years were assessed for delirium within 36 hours of admission, using the Revised Delirium Rating Scale (DRS-R98). Consenting patients without prevalent delirium then underwent daily assessment for the first week of admission for the development of delirium. The Delirium Motor Subtype Scale-4 (DMSS-4) was used to establish the motor activity profile of incident delirium. Longitudinal subtypes (hypoactive throughout; hyperactive throughout; mixed subtype throughout; no subtype throughout; variable subtype) were then ascertained by examining the daily profiles for each patient with delirium, based on pre-determined definitions. Results In 191 patients included the prospective study (i.e. non-delirious on admission; median age 80.1 years; 52.9% male), 1219 contemporaneous DRS-R98 and DMSS-4 assessments were performed. There were 61 cases of incident delirium, with 113 delirium days with motor profile established (1-6 days per case). Motor profile was generally stable (n = 45/61, 73.8%; p < 0.001). Hypoactive subtype was most prevalent on any given delirium day (n = 75/113, 66.4%) and was the most common longitudinal subtype (n = 38/61, 62.3%). Conclusions This study highlights the prevalence of hypoactive delirium in older medical inpatients, which can be subtle to the untrained eye. Future delirium education programmes should focus on improving awareness and understanding of hypoactive presentations amongst undergraduate and postgraduate clinical staff.