The modified Rivermead Mobility Index: validity and reliability

Purpose : This paper presents the evaluation of the following psychometric properties of the Modified Rivermead Mobility Index (MRMI): face/content va lidity, responsiveness, test-retest reliability, inter- rater reliability a nd internal consistency. This mobility scale represents a further developme nt of the Rivermead Mobility Index (RMI). In its new form the scoring was a dapted from a two- point to a six- point scale. The number of test items wa s reduced from fifteen to eight items in order to measure mobility- related items that physiotherapists consider being essential for demonstrating tre atment effects in patients following a stroke. Method: A consensus exercise with forty- two physiotherapists attending a s troke care conference established face/content validity. Inter- rater and t est- retest reliability were examined by assessing thirty patients by two i ndependent raters selected from a pool of eight physiotherapists in two dif ferent settings, an elderly care unit and a stroke rehabilitation unit. All patients were hospitalised and had experienced a stroke within the past si x weeks. Responsiveness was examined by calculating the effect size statist ic on the admission and discharge score of sixteen acute patients following stroke. Results : The results showed that the modified RMI was : responsive to chan ge (effect size = 1.15), stable when tested on two occasions (paired t-test = 0.732; p = 0.47), highly reliable between raters (ICC = 0.98; p < 0.001) with high internal consistency (Cronbach's alpha = 0.93). Conclusions : These results suggest that when using the Modified RMI to ass ess patients in the early stages following stroke, similar results can be o btained by different raters, regardless of experience. However there needs to be a difference of more than 4.5 points (degree of measurement error at 95 % confidence level) in the overall score to detect true changes in the p atient' s level of mobility.