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LETTERS: David Chadwick and Richard Gray Shared scheme for assessing drugs for multiple sclerosis: Dealing with uncertainties about cost effectiveness of treatments is difficult problem BMJ 2003; 326: 1212-a-1213-a [Full text]

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Better outcome measures in studies of MS do exist.

Derick T Wade   (3 June 2003)

Better outcome measures in studies of MS do exist. 3 June 2003
Derick T Wade, Professor in Neurological Disability The Oxford Centre for Enablement, Windmill Road, Oxford OX3 7LD, UK Send response to journal: Re: Better outcome measures in studies of MS do exist.	Re: Shared scheme for assessing drugs for multiple sclerosis and measurement of outcome Dear Editor, Professors Chadwick and Gray [1] repeat the often stated ‘fact’ that “there are no obviously better alternatives to the expanded disability status score” for use in studies of multiple sclerosis, especially disease modifying drugs. This ignores the evidence. The expanded disability status score (EDSS) can be faulted on many grounds. It is resource-expensive, requiring a full neurological examination if undertaken according to its derivation. It mixes different levels of disease effect, with items from the impairment level (i.e. symptoms and signs) and the activity level (i.e. mobility), which is invalid. As a measure of mobility it is insensitive and unreliable, especially as estimates of walking distance are themselves unreliable [2]. More importantly there is good evidence that other measures are better. For example the Rivermead Mobility Index (RMI) and gait speed both are better at detecting change [3], and simple measures of dexterity are also more sensitive to change [4]. Further there are some MS specific measures such as the Guy’s Neurological Disability Scale (GNDS) which have also been found to be valid, reliable and sensitive to change [5][6]. There are few remaining arguments to support continued use of the EDSS. Neurologists are undoubtedly familiar with the EDSS, but they can learn new measures and unless all change is stopped this is not an adequate reason. A common measure facilitates comparison of studies and meta-analysis, but meta-analysis would be less necessary with more sensitive measures, and protocols for allowing EDSS data and data from other measures to be compared and combined could easily be developed. Finally regulatory authorities may ‘insist’ that the EDSS is used, but the solution is to educate them that better measures exist, and not simply to accept this ‘insistence’ which probably arises from ignorance and constantly reading that “there are no obviously better alternatives to the expanded disability status score”! I would therefore strongly recommend that future studies use one or more of the many better measures that exist, and in the absence of any consensus I would commend the Rivermead Mobility Index (which is free to anyone, available in several languages, and can be completed in a few minutes). Yours faithfully, Derick Wade References 1 Chadwick D, Gray R. Shared scheme for assessing drugs for multiple sclerosis: Dealing with uncertainties about cost effectiveness of treatments is difficult problem. BMJ 2003;326:1212-1213. 2 Giantomaso T, Makowsky L, Ashworth N, Sankaran R. The validity of patient and physician estimates of walking distance. Clinical Rehabilitation 2003;17:394-401 3 Vaney C., Blaurock H., Gattlen B., Meisels C Assessing mobility in Multiple Sclerosis using the Rivermead Mobility Index and gait speed. Clinical Rehabilitation 1996;10:216-226. 4 Goodkin E, Herstgaard D, Seminary J. Upper extremity function in multiple sclerosis: improving sensitivity with box and block and nine hole pegs tests. Archives of Physical Medicine and Rehabilitation 1988;69:850-854 5 Rossier P, Wade DT. The Guy’s Neurological Disability Scale in patients with multiple sclerosis: a clinical evaluation of its reliability and validity. Clinical Rehabilitation 2002;16:75-95 6 Wade DT, Young C, Chaudhuri KR, Davidson DL. A randomized placebo controlled exploratory study of Vitamin B-12, lofepramine and L-phenylalanine (the “Cari Loder regime”) in the treatment of multiple sclerosis. Journal of Neurology, Neurosurgery and Psychiatry 2002;73:246-49 Competing interests:   No commercial interests, but I was involved in developing or studying some of the measures recommended.