Evaluating the effectiveness of interventions directed toward the treatment of preoperative anxiety in children has been hindered by the absence of a statistically valid measurement tool. In a previous investigation, we developed an instrument (Yale Preoperative Anxiety Scale [YPAS]) that can be used to assess anxiety in children undergoing induction of anesthesia. The purpose of the present investigation was to modify and expand the applicability of the instrument to the preoperative holding area and to validate the modified instrument (m-YPAS) against a recognized "gold standard" (State-Trait Anxiety Inventory for Childrens [STAIC]). Videotapes of children in a preoperative holding area were analyzed by the investigators. The existing five categories of the YPAS were found to reflect most of the behaviors observed. Several items, however, were modified to describe new behaviors observed. Reliability analysis using weighted kappa statistics revealed that inter-observer agreement ranged from 0.68 to 0.86, whereas intraobserver weighted kappa ranged from 0.63 to 0.90. Concurrent validity between the YPAS and the STAIC was acceptable (P = 0.01, r = 0.79). Construct validity was high as assessed by increased m-YPAS scores from the preoperative holding area (28 +/- 8) to entering the operating room (35 +/- 12), to introduction of the anesthesia mask (43 +/- 15;F [1,36] = 0.6, P = 0.001]. Showing good to excellent observer reliability and high concurrent and construct validity, the m-YPAS proved to be an appropriate tool for assessing children's anxiety during the perioperative period.
Implications: The absence of a statistically valid measurement tool that can be applied easily in perioperative settings hinders the evaluation of interventions directed toward treatment of preoperative anxiety in children. The authors describe the development of such a tool, the modified Yale Preoperative Anxiety Scale.