Validation of the 15-item Brief Inventory of Swallowing Ability (BISA-15) for Older Adults Based on a Rasch Analysis

Abstract

Objectives

Aging-related changes in swallowing functions have rapidly become prevalent among the elderly. Self-reported questionnaires are often conducted to observe how people perceive their swallowing functions, and to report the swallowing-associated quality-of-life. This study was conducted to demonstrate the use of Rasch analysis for validating the pre-developed self-reported questionnaire to assess swallowing functions for community-dwelling older adults.

Methods

A total of 479 older adults (men=238, mean age±SD=75.6±7.17 years) were enrolled. Twenty-six items with respect to swallowing functions were completed by the participants. Each item investigated symptom frequency or severity on a 5-point Likert scale. A Rasch analysis using the WINSTEP® program was undertaken to establish validity and reliability of the questionnaire.

Results

From the item fit statistics analysis, 11 out of 26 items were shown to be misfits to the model. Thus, the 15-item Brief Inventory of Swallowing Ability (BISA-15) was derived and demonstrated a unidimensional scale based on the dimensionality and item fit statistics. The overall item reliability was excellent. The person reliability was lower than the required threshold. The rating scales needed to collapse into three categories both in frequency and severity (i.e., never, sometimes/moderate, often/severe).

Conclusion

The BISA-15 can be utilized to detect degree of aberrations in swallowing that transit from normal to subclinical stage in older adults. Future studies are warranted to further clarify the utility of the BISA-15 in a wide range of age in the elderly as well as in the various clinical populations.