Validation and psychometric properties of the Delirium Motor Subtype Scale in elderly hip fracture patients (Dutch version)

The Delirium Motor Subtype Scale (DMSS) was developed to capture all the previous different approaches to delirium motor subtyping into one new instrument and emphasize disturbances of motor activity rather than associated psychomotoric symptoms. We investigated reliability and validity of the DMSS Dutch version. Elderly patients who had undergone hip fracture surgery received the DMSS and the Delirium Rating Scale Revised-98 (DRS-R-98). A diagnosis of delirium was defined according to the Confusion Assessment Method (CAM). Among 146 patients, 46 (32%) patients were diagnosed with delirium (mean age 86.3 years; SD 5.2). The internal consistency of the DMSS was acceptable (Cronbach's alpha = 0.72). If an item was removed at random the internal consistency of the scale remained the same. Similarly the concurrent validity of DMSS was good (Cohen's kappa = 0.73) while for each motor subtype the Cohen's kappa ranged from 0.58 to 0.85. The sensitivity and specificity of DMSS to detect each subtype ranged from 0.56 to 1 and from 0.88 to 0.98, respectively. This study suggests that the Dutch version of the DMSS is a reliable and valid instrument. The DMSS has scientific validity that could allow for greater precision in further research on motor subtypes.