Study objective: The Simplified Motor Score was recently found to exhibit equal test performance to the Glasgow Coma Scale (GCS) when predicting 4 clinically important trauma outcomes. The present study tests the interrater reliability of the Simplified Motor Scale, the GCS and its components, and 2 other simplified neurologic scales when applied to patients presenting to the emergency department with altered levels of consciousness from any cause.
Methods: In this prospective observational study, emergency physicians independently assigned the GCS, Simplified Motor Scale, and 2 4-point scales--AVPU (Alert, responds to Verbal stimuli, responds to Painful stimuli, Unresponsive) and ACDU (Alert, Confused, Drowsy, Unresponsive)--to qualifying adult subjects. Two physicians filled out prospective data forms within 5 minutes of each other while remaining blinded to each other's assessments. Data were pooled and analyzed for interrater reliability of all scales using simple agreement, unweighted kappa, Spearman's rho, and Kendall's tau-b.
Results: One hundred twenty-six subjects were enrolled, with 6 later excluded. Percentage agreements were 83% for the Simplified Motor Scale, 58% for the ACDU scale, 57% for the AVPU scale, and 42% for the Total GCS. The kappa values were 0.70 for the Simplified Motor Scale, 0.43 for ACDU, 0.41 for AVPU, and 0.32 for the Total GCS. The Simplified Motor Scale also had the highest Spearman's rho (.85) and second highest Kendall's tau-b (0.81).
Conclusion: The Simplified Motor Scale has the best interrater reliability for the assessment of altered level of consciousness of traumatic and nontraumatic cause among the scales tested.