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 consider able limitations, in order to quantify patients' communication capacity and agitated behaviour, two new operational observer-rating scales, the Commun ication Capacity Scale (Communication Scale) and Agitation Distress Scale ( Agitation Scale), were validated. Thirty terminally ill cancer patients diagnosed with delirium were evaluate d 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 inte rnal consistency and inter-rater reliability with Cronbach's alpha coeffici ents 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 com ponent for each scale. The total score on the Communication Scale was highl y 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 (r ho = 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 a gitation symptoms of terminally ill cancer patients with delirium.