Background and purpose: The Berg Balance Scale (BBS) is frequently used to assess balance in older people, but knowledge is lacking about the absolute reliability of BBS scores. The aim of this study was to investigate the absolute and relative intrarater test-retest reliability of data obtained with the BBS when it is used among older people who are dependent in activities of daily living and living in residential care facilities.
Subjects: The participants were 45 older people (36 women and 9 men) who were living in 3 residential care facilities. Their mean age was 82.3 years (SD=6.6, range=68-96), and their mean score on the Mini Mental State Examination was 17.5 (SD=6.3, range=4-30).
Methods: The BBS was assessed twice by the same assessor. The intrarater test-retest reliability assessments were made at approximately the same time of day and with 1 to 3 days in between assessments. Absolute reliability was calculated using an analysis of variance with a 95% confidence level, as suggested by Bland and Altman. Relative reliability was calculated using the intraclass correlation coefficient (ICC).
Results: The mean score was 30.1 points (SD=15.9, range=3-53) for the first BBS test and 30.6 points (SD=15.6, range=4-54) for the retest. The mean absolute difference between the 2 tests was 2.8 points (SD=2.7, range=0-11). The absolute reliability was calculated as being 7.7 points, and the ICC was calculated to .97.
Discussion and conclusion: Despite a high ICC value, the absolute reliability showed that a change of 8 BBS points is required to reveal a genuine change in function among older people who are dependent in activities of daily living and living in residential care facilities. This knowledge is important in the clinical setting when evaluating an individual's change in balance function over time in this group of older people.