Reliability, Internal Consistency, and Validity of Data Obtained With the Functional Gait Assessment

Abstract

Background and Purpose. The Functional Gait Assessment (FGA) is a 10-item gait assessment based on the Dynamic Gait Index. The purpose of this study was to evaluate the reliability, internal consistency, and validity of data obtained with the FGA when used with people with vestibular disorders. Subjects. Seven physical therapists from various practice settings, 3 physical therapist students, and 6 patients with vestibular disorders volunteered to participate. Methods. All raters were given 10 minutes to review the instructions, the test items, and the grading criteria for the FGA. The 10 raters concurrently rated the performance of the 6 patients on the FGA. Patients completed the FGA twice, with an hour's rest between sessions. Reliability of total FGA scores was assessed using intraclass correlation coefficients (2,1). Internal consistency of the FGA was assessed using the Cronbach alpha and confirmatory factor analysis. Concurrent validity was assessed using the correlation of the FGA scores with balance and gait measurements. Results. Intraclass correlation coefficients of .86 and .74 were found for interrater and intrarater reliability of the total FGA scores. Internal consistency of the FGA scores was .79. Spearman rank order correlation coefficients of the FGA scores with balance measurements ranged from .11 to .67. Discussion and Conclusion. The FGA demonstrates what we believe is acceptable reliability, internal consistency, and concurrent validity with other balance measures used for patients with vestibular disorders.