The reliability of balance, mobility and self-care measures in a population of adults with a learning disability known to a physiotherapy service

Objective: To estimate the reliability of three measures of balance, mobility and activity for use in clinical and research physiotherapy, with adults with a learning disability. Design: Prospective study to investigate test-retest and inter-rater reliability. Setting: Participants' homes and day centres. Measures: The Berg Balance Scale (BBS), the Rivermead Mobility Index (RMI) and the Barthel Activities of Daily Living Index (BI). Participants: Of the 181 adults known to the Nottingham Community Physiotherapy Service for Adults with Learning Disabilities, 64 with a known Rivermead Mobility score of less than three were excluded. Of 117 randomized, a further 21 were found to fail this criteria, 27 had acute medical, social or behavioural problems, 22 were unable to participate or refused: therefore 47 entered the study. Methods: Participants were visited in their own homes by two researchers on two occasions, one week apart and rated independently by each rater. Agreement was assessed with the kappa statistic (k) and percentage agreement for each item in each scale, and described using standard classification. Intraclass correlation coefficients for inter-rater and test-retest total scores and average differences of total scores, their standard deviations and limits of agreement, were calculated. Results: For inter-rater observations, the Barthel Index and the Rivermead Mobility Index had almost perfect agreement (k=0.86–1.00 and 0.89–1.00 respectively), with the Berg Balance Scale having substantial to almost perfect agreement (k=0.74–1.00). For test–retest comparisons, both the Barthel Index and the Rivermead Mobility Index demonstrated moderate to almost perfect agreement (k=0.57–1.00 and 0.45–1.00 respectively). Kappa scores for the Berg Balance Scale varied from low to almost perfect agreement (k=0.37–1.00). Conclusions: The Berg Balance Scale, Rivermead Mobility Index and Barthel Activities of Daily Living Index are all reliable clinical and research tools for physiotherapists working with adults with learning disabilities.