Abstract
BACKGROUND: The congruence or discordance between actual and perceived balance ability has been proposed to be linked to functional outcomes such as falls. However, gaps remain in our ability to quantify discordance, and its relationship to relevant outcomes. OBJECTIVE: To investigate a novel quantification of concordance/discordance between balance performance and perception and determine the relationship to falls among people with Parkinson's disease (PwPD). METHODS: Data from 244 PwPD were aggregated from 5 previously conducted studies. Variables extracted included age, sex, Activities-Specific Balance Confidence scale (ABC; perceived balance), Timed Up and Go (TUG; balance performance), Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS-UPDRS) part III scores, and retrospective falls (6- or 12-month). Data validation between studies was established. Discordance was quantified as the difference between an individual's predicted ABC, based upon their TUG score, to their reported ABC. RESULTS: Two methods for calculating discordance were tested: simple linear regression and segmented regression. As there were no differences between the bootstrap distributions of both approaches (P = .520), simple linear regression was utilized for the subsequent logistic regression model. Discordance was the only statistically significant predictor of fall status (OR = 0.98, P = .003), after controlling for age, MDS-UPDRS part III, sex, and TUG. The inclusion of discordance in the logistic regression model boosted the predictive accuracy by 58%. CONCLUSIONS: Discordance between actual and perceived balance was uniquely related to retrospective fall history among PwPD. Clinicians and researchers should consider discordance between actual and perceived balance as a potentially modifiable target to minimize falls.