RELIABILITY OF BALANCE EVALUATION SYSTEMS TEST IN EVALUATING BALANCE PERFORMANCE IN OLDER PEOPLE WITH VISUAL IMPAIRMENT

W.W.S. Lam¹, M.K.Y. Mak¹

Background: Elderly with visual impairment have higher risk of falls than their sighted peers. Fall prevention is essential for this vulnerable population while 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 system approach to determine the underlying causes of balance deficits. The psychometric properties of the BESTest have been evaluated in adults with Parkinson’s disease, stroke and other neurological conditions but not the visually impaired population.

Purpose: The study aimed to determine whether the BESTest is a reliable assessment tool to evaluate balance performance in older people with visual impairment.

Methods: A prospective cohort study design was adopted for this study. Forty older people with severe visual impairment & blindness (i.e. visual acuity ≤ 20/200 according to the WHO definition) were recruited. They were evaluated with BESTest for visually impaired (BESTest-VI) where testing procedures for items 25 to 27 of BESTest were modified to accommodate older people with visual impairment. BESTest-VI has 36 items, which score from 0-3, with a total of 108 points, converted to 0-100%, and  a higher percent score indicating better balance. The BESTest-VI was administered by two experienced physiotherapists who are working with older people with visual impairment for more than 15 years. These physiotherapists evaluated all participants with BESTest-VI independently in the same day for establishing the inter-rater reliability. For testing the intra-rater reliability, the same 40 participants were reassessed by the same rater after an interval of 48 to 72 hours.

Results: Participants had a mean age of 81.6 ± 9.5 years old. The mean total score for BESTest-VI for the participants is 71.2% ± 9.8%. The BESTest-VI had excellent inter-rater reliability for the total score (ICC = 0.970) and subsection scores (ICC = 0.816 to 0.924). The BESTest-VI had excellent intra-rater reliability in both the total score (ICC = 0.994) and subsection scores (ICC =0.948 to 0.993).

Conclusion(s): The BESTest-VI total and subsection scores demonstrated excellent inter-rater and intra-rater reliability in assessing balance function in older people with visual impairment. The high level of reliability may facilitate the use of BESTest-VI in visually impaired older adults. Future study is needed to establish the criterion and predictive validity of BESTest-VI in this population.

Implications: With better understanding of the balance control among visually impaired older adults, it could guide the clinical decision and the design of specific fall prevention intervention. Preliminary evidence generated from this study will provide important clinical evidence for the usage of the BESTest-VI in older people with visual impairment.

Funding, acknowledgements: None. No funding to declare.

Keywords: BESTest, Visually impairment, Balance

Topic: Older people

Did this work require ethics approval? Yes

Institution: The Hong Kong Polytechnic University

Committee: The Hong Kong Polytechnic University

Ethics number: HSEARS20180919005