Table 1

 Behaviour of change in the Multiple Sclerosis Impact Scale-29 physical score in relation to change in Expanded Disability Status Scale

EDSS range 0–5EDSS range 5.5–8.5
EDSS, Expanded Disability Status Scale; MSIS, Multiple Sclerosis Impact Scale; ROC, receiver operating characteristic.
Summary of the behaviour of the physical component of the MSIS (MSIS-29 physical) in a cohort of 214 patients followed for up to 4 years in relation to their EDSS status. The correlation of MSIS-29 change scores with EDSS change was stronger in the upper range of EDSS disability with more robust sensitivity, specificity and predictive values. However, the MSIS-29 scores in stable patients in the range EDSS 5.5–8.5 tended to improve at follow-up, consistent with the phenomenon of response shift*.
Stability: no change in EDSS effect size0.01−0.57*
Responsiveness
    Effect size : EDSS+1 step0.571.4
    Effect size : EDSS+2 steps1.11.8
    Effect size : EDSS+3 stepsNot available3.4
Responsiveness : slope of linear correlation of change in MSIS-29 physical v change in EDSS6.7 (95% CI 3.3 to 10.1)8.1 (95% CI 5.5 to 10.7)
Correlation of change in MSIS-29 vs change in EDSS0.33 (p<0.0002)0.56 (p<0.0001)
Minimally important MSIS-29 physical change score78
ROC: area under curve0.725 (p<0.0001)0.854 (p<0.0001)
    Sensitivity78%87%
    Specificity51%67%
    Accuracy69%80%
    Positive predictive value50%82%
    Negative predictive value77%78%