Clinical approach to balance intensity in people with multiple sclerosis: clinical judgment versus the Balance Intensity Tool for Exercise – an inter-rater agreement and reliability study

Objective Balance training is essential for enhancing stability in people with multiple sclerosis (PwMS). However, guidance on exercise intensity remains vague and largely relies on clinical judgment as standardized assessment methods are absent. This study introduces and evaluates the Balance Intensity Tool for Exercise (BITE), a standardized method for assessment of balance intensity based on observable errors, and compares it with traditional clinical judgment.Methods Sixty-one PwMS, recruited from physiotherapy clinics and social networks, performed two balance tasks: line-walking and tandem-stance. The tasks were videorecorded for subsequent intensity assessment. Intensity was rated using (1) BITE, where three assessors measured the percentage of time with observable errors as a measure of intensity, and (2) clinical judgment, where three experienced physiotherapists scored intensity on a 0–100 scale. Balance capacity was measured with the Mini-BESTest. BITE assessors and clinicians were blinded to each other’s ratings. Inter-rater agreement, reliability, and measurement error were evaluated using Bland–Altman analysis with 95% Limits of Agreement (LoA), Intra-class Correlation Coefficient (ICC2,1), and Standard Error of Measurement (SEM). Associations with balance capacity were examined using Spearman’s rank correlation.Results Intensities measured by BITE were consistently lower than clinical judgment (line-walking median: 36% vs. 74%; tandem-stance median: 23% vs. 53%). BITE demonstrated excellent inter‑rater reliability (ICC2,1 > 0.9). Narrower pairwise LoA (up to ±20% vs. up to ±36%) and lower SEM (up to 8.3 vs. up to 11.2) were observed when compared to clinical judgment. Both methods demonstrated identical correlations with balance performance as measured by the Mini-BESTest (Spearman’s rho: –0.82).Conclusion BITE provides a quantifiable method to describe balance exercise intensity in PwMS based on the time of observed performance errors. BITE demonstrated excellent inter-rater reliability and inter-rater agreement, with LoA ≤ 20%, while clinical judgment exhibited wider LoA. Further research should explore its applicability in other populations with impaired balance.