Association of the RASS Score with Intensity of Symptoms, Discomfort, and Communication Capacity in Terminally Ill Cancer Patients Receiving Palliative Sedation: Is RASS an Appropriate Outcome Measure?

BackgroundPalliative sedation is sometimes needed for refractory symptoms, and the Richmond Agitation-Sedation Scale (RASS) is one of the key measures. The primary aim of this study was to explore the association between the RASS score and degree of distress quantified by other measures: Support Team Assessment Schedule, item 2 (STAS), Discomfort Scale for Dementia of Alzheimer Type (Discomfort Scale), and Non-communicative Patient’s Pain Assessment Instrument (NOPPAIN), as well as a communication capacity measured by the Communication Capacity Scale, item 4 (CCS).MethodsThis was a prospective observational study on terminally ill cancer patients who received continuous infusion of midazolam to relieve refractory symptoms in a palliative care unit of a designated cancer hospital. Primarily responsible palliative care physicians rated RASS, Discomfort Scale, NOPPAIN, and CCS just before starting infusion, and 1 hour, 4 hours, 24 hours, and 48 hours after midazolam infusion, and ward nurses rated STAS at the same time. Since the ward nurses regularly evaluated STAS to titrate midazolam during palliative sedation as routine work, we regarded STAS rated by ward nurses as a standard of distress measure.ResultsA total of 249 assessments were performed for 55 patients. The RASS score was moderately to highly associated with symptom intensity measured by STAS, discomfort measured by the Discomfort Scale, and pain measured by NOPPAIN (r = 0.63 to 0.73). On the other hand, communication capacity measured by CCS is not parallel with the RASS score, and demonstrated a valley-shape. In 82 assessments with RASS of -1 to -3, 11 patients (13%) were regarded as having physical symptoms of STAS of 2 or more.Conclusions RASS can roughly estimate physical distress in patients receiving palliative sedation, but a measure to more precisely quantify the symptom experience is needed.