Author: Lam, Wai Shun Wilson
Title: Reliability and validity of using balance evaluation systems test in evaluating balance performance in older people with visual impairment
Advisors: Mak, Margaret (RS)
Degree: DHSc
Year: 2022
Subject: Falls (Accidents) in old age -- Prevention
Older people with visual disabilities
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Health and Social Sciences
Pages: 200 pages : color illustrations
Language: English
Abstract: Older adults with visual impairment (VI) have higher risk of falls compared to their sighted peers. Fall prevention is essential for this vulnerable population. Currently there is no comprehensive assessment tool for evaluating their balance control domains. The Balance Evaluation Systems Test (BESTest) is a reliable and validated measurement scale which uses a systematic approach to determine the underlying causes of balance deficits. The BESTest allows the development of interventions according to the specific postural control domain(s) affected in each client. The psychometric properties of the BESTest have not been evaluated in the visually impaired population. The study aims at modifying the original BESTest into BESTest-VI to adapt to special characteristics of people with VI, and examining the psychometric properties of BESTest-VI. This prospective cohort study involved ninety older adults (mean (SD) age: 82.0 ± 9.0 years old) with severe visual impairment or blindness (i.e. visual acuity < 20/200 according to the WHO definition). Each participant was evaluated with BESTest-VI, Berg Balance Scale (BBS), visual acuity test and the Montreal Cognitive Assessment Hong Kong Version 5-minutes Protocol (HK-MoCA 5-minutes Protocol). BESTest-VI was administered by two raters on the same day and one of the raters repeated the test after an interval of two to three days. Both BESTest-VI total score (ICC(3,1) = 0.994) and sub-section scores (ICC(3,1) = 0.948 to 0.993) demonstrated excellent intra-rater reliability. BESTest-VI had excellent inter-rater reliability in both the total score (ICC(2,1) = 0.970) and sub-section scores (ICC(2,1) = 0.816 to 0.924). BESTest-VI showed strong correlation with the BBS (Spearman's correlation coefficient = 0.86, p < 0.001), thus revealing good concurrent validity. The minimal detectable change at 95% confidence level (MDC95) was 6.6% for the total percentage score, and 7.0% to 18.4% for the sub-section scores. Good known-group validity was established, as BESTest-VI was effective in distinguishing participants in different age groups with different mobility levels. Unidimensionality was identified for BESTest-VI to support its structural validity. All BESTest-VI sub-sections showed good internal consistency (Cronbach's alpha ranged from 0.74 to 0.85) except sub-section "Sensory orientation" (Cronbach's alpha = 0.56). BESTest-VI was able to predict falls in the six-month follow-up period with moderate accuracy (area under the curve = 0.78). The proposed cut-off score in identifying fallers was 63.4%, with good sensitivity of 80.0% and moderate specificity of 65.0%. BESTest-VI had no substantial floor and ceiling effects, and the use of BESTest-VI in participants with different mobility levels is well supported. To conclude, BESTest-VI has good reliability and validity in assessing balance functions in older adults with VI. The findings support the use of BESTest-VI in seniors with visual impairment. With better understanding of balance control among older visually impaired individuals, it could guide clinical decisions and the design of specific fall prevention interventions. Future studies with larger population size is warranted to improve the generalizability and enhance the clinical utilization of BESTest-VI.
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Access: restricted access

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