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Page last updated:05-Sep-2013

Kurtzke EDSS Scale

Most of the studies in MS use the Kurtzke Expanded Disability Status Scale (EDSS) to determine whether people in the study get better or worse. It was devised by Kurtzke in 1983, based on the findings of neurological examination.1 In most studies, so that there is no bias, neurologists who grade the patients are unaware of whether or not the patients are in the treatment or control groups. This is called blinding. A double blind trial is one in which the patient doesn’t know whether the substance he or she is taking is the active drug or the inactive placebo, or which of two therapies it is (if two therapies are being compared), and the neurologist doesn’t know either. So you will often see the description randomised, double-blind, placebo-controlled trial (RCT).

Kurtzke’s EDSS scores 8 functional systems from 0 for normal to 5 or 6 for maximal impairment. Based on these functional system scores and the person’s ability to walk, the EDSS is determined. The EDSS goes in half point scores from 0.0 for normal to 10.0 for dead from MS. From 0.0-4.0, people are able to walk without assistance, and the EDSS is derived from the functional system scores. From 4.0-7.5, the EDSS score comes mainly from how far the person can walk and with what assistance. Essentially, point 6 on the scale represents walking with a cane, and this point is often used as an endpoint in studies looking at progression of disability. From 7.5-10.0, the main determinant of EDSS is the person’s ability to transfer from wheelchair to bed and to self-care.

The disability rating scale is based upon neurological testing and examination, looking for abnormalities in functional systems. The EDSS in detail is laid out below, in relation to the functional systems it affects; the functional systems are: pyramidal (motor functions like walking), cerebellar (coordination), brain stem (speech and swallowing), sensory (touch, vibration and pain), bowel and bladder functions, visual, mental, and any other (includes any other neurological findings due to MS).

EDSS

0.0: Normal neurological exam.
1.1: No disability, but minimal signs in one functional system (FS).
1.5: No disability, but minimal signs in more than one FS.
2.0: Minimal disability in one FS.
2.5: Mild disability in one FS or minimal disability in two FS.
3.0: Moderate disability in one FS or mild disability in three or four FS. However, the person is still fully ambulatory.
3.5: The person is fully ambulatory, but has moderate disability in one FS and mild disability in one or two FS; or moderate disability in two FS; or mild disability in five FS.
4.0: The person is fully ambulatory without aid, and is up and about most of the day (12 hours) despite relatively severe disability. He or she is able to walk 500 meters without aid or rest.
4.5: The person is fully ambulatory without aid, and is up and about much of day. He or she is able to work a full day, but may otherwise have some limitations of full activity or require minimal assistance. This is considered relatively severe disability. Able to walk 300 meters without aid.
5.0: The person is able to walk 200 meters without aid or rest. Disability impairs full daily activities, such as working a full day without special provisions.
5.5: The person is able to walk 100 meters without aid or rest. Disability precludes full daily activities.
6.0: The person needs intermittent or unilateral constant assistance (cane, crutch or brace) to walk 100 meters with or without resting.
6.5: The person needs constant bilateral support (cane, crutch or braces) to walk 20 meters without resting.
7.0: The person is unable to walk beyond five meters even with aid, and is essentially restricted to a wheelchair. However, he or she wheels self and transfers alone, and is active in wheelchair about 12 hours a day.
7.5: The person is unable to take more than a few steps and is restricted to wheelchair, and may need aid to transfer. He or she wheels self, but may require a motorized chair for a full day’s activities.
8.0: The person is essentially restricted to bed, a chair or a wheelchair, but may be out of bed much of day. He or she retains self care functions and has generally effective use of arms.
8.5: The person is essentially restricted to bed much of day, but has some effective use of arms and retains some self care functions.
9.0: The person is confined to bed, but still able to communicate and eat.
9.5: The person is totally helpless and bedridden and is unable to communicate effectively or eat and swallow.
10.0: Death due to MS.
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While this scale is widely used in most MS studies, it is not used a lot in day-to-day medicine, and is a bit insensitive to changes in people’s conditions, particularly once they have difficulty walking. These shortcomings of the EDSS have been described: the EDSS over-emphasises the ability to walk, is insensitive to cognitive dysfunction in MS, calculating EDSS scores is complicated, with complex rules for rating findings on neurological exam and translating these into scores on functional system status, and the EDSS is not sensitive to many clinical changes that a person with MS experiences. Most neurologists do not use EDSS scores to monitor patients, although they are frequently reported in the context of clinical trials.
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  1. Kurtzke JF. Rating neurological impairment in multiple sclerosis: an expanded disability scale. Neurology 1983; 33:1444-1452.