Monitoring Sedation Status Over Time in ICU Patients: Reliability and Validity of the Richmond Agitation-Sedation Scale (RASS)

CONTEXT Goal-directed delivery of sedative and analgesic medications is recommended as standard care in intensive care units (ICUs) because of the impact these medications have on ventilator weaning and ICU length of stay, but few of the available sedation scales have been appropriately tested for reliability and validity. OBJECTIVE To test the reliability and validity of the Richmond Agitation-Sedation Scale (RASS). DESIGN Prospective cohort study. SETTING Adult medical and coronary ICUs of a university-based medical center. PARTICIPANTS Thirty-eight medical ICU patients enrolled for reliability testing (46% receiving mechanical ventilation) from July 21, 1999, to September 7, 1999, and an independent cohort of 275 patients receiving mechanical ventilation were enrolled for validity testing from February 1, 2000, to May 3, 2001. MAIN OUTCOME MEASURES Interrater reliability of the RASS, Glasgow Coma Scale (GCS), and Ramsay Scale (RS); validity of the RASS correlated with reference standard ratings, assessments of content of consciousness, GCS scores, doses of sedatives and analgesics, and bispectral electroencephalography. RESULTS In 290-paired observations by nurses, results of both the RASS and RS demonstrated excellent interrater reliability (weighted κ, 0.91 and 0.94, respectively), which were both superior to the GCS (weighted κ, 0.64; P