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 0–5	EDSS range 5.5–8.5
Stability: no change in EDSS effect size	0.01	−0.57*
Responsiveness
Effect size : EDSS+1 step	0.57	1.4
Effect size : EDSS+2 steps	1.1	1.8
Effect size : EDSS+3 steps	Not available	3.4
Responsiveness : slope of linear correlation of change in MSIS‐29 physical v change in EDSS	6.7 (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 EDSS	0.33 (p<0.0002)	0.56 (p<0.0001)
Minimally important MSIS‐29 physical change score	7	8
ROC: area under curve	0.725 (p<0.0001)	0.854 (p<0.0001)
Sensitivity	78%	87%
Specificity	51%	67%
Accuracy	69%	80%
Positive predictive value	50%	82%
Negative predictive value	77%	78%

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*.