Concordance between the delirium motor subtyping scale (DMSS) and the abbreviated version (DMSS-4) over longitudinal assessment in elderly medical inpatients

James Fitzgerald, Niamh O’Regan, Dimitrios Adamis, Suzanne Timmons, Colum Dunne, Paula Trzepacz, David Meagher

Delirium is a common neuropsychiatric syndrome that includes clinical subtypes identified by the Delirium Motor Subtyping Scale (DMSS). We explored the concordance between the DMSS and an abbreviated 4-item version in elderly medical inpatients. Elderly general medical admissions (n = 145) were assessed for delirium using the Revised Delirium Rating scale (DRS-R98). Clinical subtype was assessed with the DMSS (which includes the four items included in the DMSS-4). Motor subtypes were generated for all patient assessments using both versions of the scale. The concordance of the original and abbreviated DMSS was examined. The agreement between the DMSS and DMSS-4 was high, both at initial and subsequent assessments (κ range 0.75-0.91). Intraclass Correlation Coefficient (ICC) for all three raters for the DMSS was high (0.70) and for DMSS-4 was moderate (0.59). Analysis of the agreement between raters for individual DMSS items found higher concordance in respect of hypoactive features compared to hyperactive. The DMSS-4 allows for rapid assessment of clinical subtype in delirium and has high concordance with the longer and well-validated DMSS, including over longitudinal assessment. There is good inter-rater reliability between medical and nursing staff. More consistent clinical subtyping can facilitate better delirium management and more focused research effort.