The Persian version of the Berg Balance Scale: inter and intra-rater reliability and construct validity in elderly adults

Purpose: As a well-known measure for quantifying functional mobility in elderly persons, Berg Balance Scale (BBS) was used in the present study to evaluate its psychometric properties among a sample of 106 elderly individuals speaking Persian language. Method: After forward-backward translation process, videotapes were recorded from all participants while performing 14 tasks of the BBS. The volunteers were also asked to perform the Timed Up and Go (TUG) test at the same session. To determine inter and intra-rater reliability, the videotapes were viewed by two experienced therapists while one of the raters assessed the videotaped performance of the subjects on a second occasion. Results: Intraclass correlation coefficients (95% confidence interval) of 0.93 (0.87 0.96) and 0.95 (0.92 0.97) were obtained for inter and intra-rater reliability, respectively. Cronbach's alpha was 0.62 which is marginally lower than the cut-off point of 0.70. Furthermore, there were no ceiling and floor effects for the Persian version. In terms of construct validity, the BBS had a negative and strong correlation with the TUG (r = -0.74, p < 0.001). Conclusions: Acceptable levels of intra and inter-rater reliability with a moderate internal consistency and high validity were demonstrated for the Persian version of BBS.