Measurement Properties of the Functional Balance Ability Measure Across Subacute Neurologic Diagnoses

Area of Science:

• Neurology
• Rehabilitation Medicine
• Psychometrics

Background:

• Subacute neurologic conditions often impair balance, necessitating reliable assessment tools.
• The Functional Balance Ability Measure (FBAM) is used to evaluate balance in this population.
• Rasch analysis is a valuable psychometric tool for evaluating measurement properties.

Purpose of the Study:

• To evaluate the measurement properties of the Functional Balance Ability Measure (FBAM) in individuals with subacute neurologic conditions.
• To assess the unidimensionality, reliability, and item hierarchy of the FBAM using Rasch analysis.
• To examine the stability of the FBAM's item hierarchy across different neurologic diagnostic groups.

Main Methods:

• Retrospective, cross-sectional analysis of data from 841 individuals in an inpatient rehabilitation facility.
• Rasch analysis with the Andrich Rating Scale Model was applied to FBAM item-level scores.
• Principal component analysis of residuals and differential item functioning (DIF) were used to assess unidimensionality and item bias.

Main Results:

• The FBAM demonstrated unidimensionality, an appropriate rating scale structure, and high person reliability (0.91).
• The measure effectively separated individuals into 6 distinct balance ability groups.
• Marginal differential item functioning (DIF) was observed for specific items in certain diagnostic groups, and a floor effect was noted in 21% of the sample.

Conclusions:

• The FBAM is a unidimensional and reliable measure for assessing balance in individuals with subacute neurologic injuries.
• Differential item functioning (DIF) analyses support the FBAM's construct validity by confirming a stable balance ability hierarchy.
• Future research should focus on addressing the identified floor effect of the FBAM.