Between-rater Reliability of the 6-minute Walk Test, Berg Balance Scale, and Handheld Dynamometry in People with Multiple Sclerosis

This study investigated the between-rater reliability of the Berg Balance Scale (BBS), 6-Minute Walk test (6MW), and handheld dynamometry (HHD) in people with multiple sclerosis (MS). Previous studies that examined BBS and 6MW reliability in people with MS have not used more than two raters, or analyzed different mobility levels separately. The reliability of HHD has not been previously reported for people with MS. In this study, five physical therapists assessed eight people with MS using the BBS, 6MW, and HHD, resulting in 12 pairs of data. Data were analyzed using intraclass correlation coefficients (ICCs), Spearman correlation coefficients (SCCs), and Bland and Altman methods. The results suggest excellent agreement for the BBS (SCC = 0.95, mean difference between raters [d̄] = 2.08, standard error of measurement [SEM] = 1.77) and 6MW (ICC = 0.98, d̄ = 5.22 m, SEM = 24.76 m) when all mobility levels are analyzed together. Reliability is lower in less mobile people with MS (BBS SCC = 0.6, d̄ = -1.83; 6MW ICC = 0.95, d̄ = 20.04 m). Although the ICC and SCC results for HHD suggest good-to-excellent reliability (0.65-0.85), d̄ ranges up to 17.83 N, with SEM values as high as 40.95 N. While the small sample size is a limitation of this study, the preliminary evidence suggests strong agreement between raters for the BBS and 6MW and decreased agreement between raters for people with greater mobility problems. The mean differences between raters for HHD are probably too high for it to be applied in clinical practice.