The modified rivermead mobility index: Reliability and convergent validity in a mixed neurological population

Purpose.To assess the inter-rater reliability, internal consistency and convergent validity of the Modified Rivermead Mobility Index (MRMI) in a mixed neurological population. Method.The MRMI was scored for 30 consecutive patients (mean age 54.5±15.6 years) by two individual testers. Reliability was examined using intraclass correlation coefficients (ICC3,1) and Bland and Altman plots; internal consistency reliability using Cronbach's alpha (α) and convergent validity using Spearman's correlation coefficient (ρ) test to compare the MRMI to the 10-m walk test as a gold standard of mobility. As the majority of patients had bilateral deficits, the MRMI was measured and added independently for both sides. Results.The inter-rater reliability was excellent: ICC (95 CI)0.93(0.86, 0.96). The Bland and Altman plots contained most data points and there was perfect agreement between raters bilaterally in 27 of cases, with a difference of one point in 60 of cases on the left and 63 of cases on the right. Internal consistency was good at α0.72 (Rater 1) and 0.80 (Rater 2). The Spearman ρ between MRMI and the 10-m walk test was high at 0.86. Conclusions.The MRMI was shown to have high levels of reliability in a mixed neurological population but we recommend that its psychometric properties are further investigated to establish the true clinical utility of this measure.