Development of an Agitation Rating Scale for Use with Acute Presentation Behavioral Management Patients
Agitation is a distressing set of behaviors frequently observed in emergency department psychiatry patients. Key to developing and evaluating treatment strategies aimed at decreasing and preventing agitation is the availability of a reliable, valid instrument to measure behaviors representative of agitation. Currently, an agitation rating instrument appropriate for use in the emergency setting does not exist and clinicians are left without standard language for communicating about the phenomenon. The Agitation Severity Scale was developed to fill this void using facilitated focus groups to generate an initial item pool. Beginning evidence of content validity was established through a survey of clinical providers and a panel of content experts. The objectives of this methodological study were to: (a) develop an observation-based rating scale to assess the continuum of behaviors known as agitation in adult emergency department patients, and (b) to evaluate the psychometric properties of the newly developed instrument. Psychometric evaluation was conducted using a sample of 270 emergency department psychiatric patients. A 17-item instrument with a standardized Cronbach's alpha coefficient of 0.91 resulted, providing evidence of a high degree of internal consistency reliability. Principle components analysis revealed a 4-component solution accounting for 69% of observed variance. Internal consistency reliability ranged from 0.71 to 0.91 for the scale components. Equivalence reliability was established through the evaluation of Agitation Severity Scores assigned by independent evaluators, r = 0.99, &kappa = 0.98. Construct validity was established through comparison of mean scores for subjects in the highest and lowest scoring quartiles. A statistically significant difference in scores was noted when comparing these groups, t = -17.688, df = 155, p < 0.001. Convergent validity was evaluated by testing the association between Agitation Severity Scores and scores obtained using a well-established instrument, the Overt Agitation Severity Scale. Pearson's correlation coefficient for the associations between the scores ranged from 0.91 to 0.93, indicating a strong, positive relationship between the scores. Finally, the Rasch measurement model was employed to further evaluate the functioning of the instrument. In sum, the Agitation Severity Scale was found to be reliable and valid when used to measure agitation in the emergency setting.