Functional gait assessment and balance evaluation system test: reliability, validity, sensitivity, and specificity for identifying individuals with Parkinson disease who fall

Abstract

Background: Gait impairments, balance impairments, and falls are prevalent in individuals with Parkinson disease (PD). Although the Berg Balance Scale (BBS) can be considered the reference standard for the determination of fall risk, it has a noted ceiling effect. Development of ceiling-free measures that can assess balance and are good at discriminating "fallers" from "nonfallers" is needed.

Objective: The purpose of this study was to compare the Functional Gait Assessment (FGA) and the Balance Evaluation Systems Test (BESTest) with the BBS among individuals with PD and evaluate the tests' reliability, validity, and discriminatory sensitivity and specificity for fallers versus nonfallers.

Design: This was an observational study of community-dwelling individuals with idiopathic PD.

Methods: The BBS, FGA, and BESTest were administered to 80 individuals with PD. Interrater reliability (n=15) was assessed by 3 raters. Test-retest reliability was based on 2 tests of participants (n=24), 2 weeks apart. Intraclass correlation coefficients (2,1) were used to calculate reliability, and Spearman correlation coefficients were used to assess validity. Cutoff points, sensitivity, and specificity were based on receiver operating characteristic plots.

Results: Test-retest reliability was .80 for the BBS, .91 for the FGA, and .88 for the BESTest. Interrater reliability was greater than .93 for all 3 tests. The FGA and BESTest were correlated with the BBS (r=.78 and r=.87, respectively). Cutoff scores to identify fallers were 47/56 for the BBS, 15/30 for the FGA, and 69% for the BESTest. The overall accuracy (area under the curve) for the BBS, FGA, and BESTest was .79, .80, and .85, respectively.

Limitations: Fall reports were retrospective.

Conclusion: Both the FGA and the BESTest have reliability and validity for assessing balance in individuals with PD. The BESTest is most sensitive for identifying fallers.

Figure 1.

Distribution of scores for the Berg Balance Scale (BBS), Functional Gait Assessment (FGA), and Balance Evaluation Systems Test (BESTest). K-S=one-sample Kolmogorov-Smirnov Test.

Figure 2.

Receiver operating characteristic plot for the Berg Balance Scale (BBS), Functional Gait Assessment (FGA), and Balance Evaluation Systems Test (BESTest). A black box shows the cutoff values chosen for each test by maximizing sensitivity and specificity. An X shows the cutoff value chosen by maximizing sensitivity and minimizing negative likelihood ratio.