Expanded Disability Status Scale (EDSS)

Method

Expanded Disability Status Scale, rated by a neurologist from the standard neurological examination and functional system scores, from 0 to 10 in half-point steps.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

CRITICAL SIGN INVERSION against the Multiple Sclerosis Functional Composite, the other disability instrument reported in the same trials: this is a DISABILITY score that improves by FALLING, while the MSFC is a performance z-score that improves by RISING, and both are described as measuring 'disability'. Also distinct from confirmed disability progression, a time-to-event dichotomisation of this same scale — recording the score and a progression endpoint derived from it as independent evidence double-counts — and from relapse rate, which measures events rather than accumulated deficit. Note the scale is ordinal and heavily ambulation-weighted between 4.0 and 6.5, so mean differences are not linear in disability.