Delirium is a common neuropsychiatric syndrome with considerable heterogeneity that includes a variety of clinical (motor) subtypes. Because delirium is typically highly fluctuating, understanding the longitudinal stability of subtypes is crucial to evaluating their relevance to treatment and outcome.

to examine the changes (variability) in motor subtype profile in patients with delirium over serial assessment using the Delirium Motor Subtype Scale, and to investigate predictors of variability.

We studied motor subtype profile of patients with delirium assessed daily over a week in elderly patients undergoing hip fracture surgery. A Generalized Estimating Equations Model examined possible predictors of change in motor subtype status, including baseline variables and delirium course.

We included 118 patients developing DSM-IV delirium after hip-surgery [mean age 87.0±6.5 years; range 65–102; 66% females]. At first assessment, hyperactive subtype was most common (49%), followed by hypoactive (31%) and mixed subtype (14%), with 6% of delirious patients not fulfilling criteria of any DMSS-defined motor subtype. Almost two-thirds (n=69) of these patients underwent at least one more assessment, and for these 45 (57%) remained stable in motor subtype over time, while the rest 34 (43%) underwent change. A range of baseline characteristics were not significant predictors of variability in subtype profile.

Motor subtype profile is typically stable for orthopaedic patients with delirium. Thus evidence from cross-sectional studies of motor subtypes can be applied to many patients with delirium. Further longitudinal studies can clarify the stability of motor subtypes across different clinical populations.