Communication Capacity Scale and Agitation Distress Scale to measure the severity of delirium in terminally ill cancer patients: a validation study.

Although valid measurement of the severity of terminal delirium is of great importance in palliative care settings, existing instruments have considerable limitations. In order to quantify patients' communication capacity and agitated behaviour, two new operational observer-rating scales, the Communication Capacity Scale (Communication Scale) and Agitation Distress Scale (Agitation Scale), were validated. Thirty terminally ill cancer patients diagnosed with delirium were evaluated simultaneously by two palliative care physicians blinded to each other's coding using the Communication Scale and Agitation Scale. In addition, the Memorial Delirium Assessment Scale (MDAS), Delirium Rating Scale (DRS) and Sedation Scale were rated by one researcher. Both scales achieved high internal consistency and inter-rater reliability with Cronbach's alpha coefficients of 0.91 and 0.96, and Cohen's kappa values on each item of 0.72-1.00. The principal components analysis resulted in the emergence of only one component for each scale. The total score on the Communication Scale was highly associated with that of the MDAS (rho = 0.78), Sedation Scale (rho = 0.86), and cognitive items from the MDAS and DRS (rho = 0.83). The whole score on the Agitation Scale was significantly correlated with that of the DRS (rho = 0.61) and agitation items from the MDAS and DRS (rho = 0.61). In conclusion, the Communication Scale and Agitation Scale have acceptable reliability and validity to quantify patients' communication capacity and agitation symptoms of terminally ill cancer patients with delirium.