Multiple Sclerosis Centers of Excellence
Kurtzke Expanded Disability Status Scale
Marsha L Tarver, PhD, MA -- Seattle, WA
The Kurtzke Disability Status Scale (DSS) was developed by Dr. John Kurtzke in the 1950s to measure the disability status of people with multiple sclerosis. The purpose was to create an objective approach to quantify the level of functioning that could be widely used by health care providers diagnosing MS. The scale was modified several times to more accurately reflect the levels of disabilities clinically observed. The scale was renamed the Kurtzke Expanded Disability Status Scale (EDSS).
The EDSS provides a total score on a scale that ranges from 0 to 10. The first levels 1.0 to 4.5 refer to people with a high degree of ambulatory ability and the subsequent levels 5.0 to 9.5 refer to the loss of ambulatory ability. The range of main categories include (0) = normal neurologic exam; to (5) = ambulatory without aid or rest for 200 meters; disability severe enough to impair full daily activities; to (10) = death due to MS. In addition, it also provides eight subscale measurements called Functional System (FS) scores. These subscale categories are listed below. The levels of function within each category refer to the eight functional systems affected by MS.
Eight Functional Systems (FS) and Their Abbreviations:
- Pyramidal (motor function) (P)
- Cerebellar (C11)
- Brainstem (BS)
- Sensory (S)
- Bowel and Bladder (BB)
- Visual (V)
- Cerebral or Mental (Cb)
- Other (O)
The Functional Systems (FS) are scored on a scale of 0 (low level of problems) to 5 (high level of problems) to best reflect the level of disability observed clinically. The “Other” category is not rated numerically, but measures disability related to a particular issue, like motor loss.
In contrast, the total EDSS score is determined by two factors: gait and FS scores. EDSS scores below 4.0 are determined by the FS scores alone. People with EDSS scores of 4.0 and above have some degree of gait impairment. Scores between 4.0 and 9.5 are determined by both gait abilities and the FS scores. For simplicity, many experts gauge the EDSS scores between 4.0 and 9.5 entirely by gait, without considering the FS scores. The EDSS is widely used and accepted as a valid tool to clinically measure and evaluate MS patients’ level of functioning.
For More Information:
National MS Society Kurtzke Expanded Disability Status Scale (EDSS)
Medscape Article Kurtzke Expanded Disability Status Scale
WedMD article How MS Disability Is Measured
EDMUS project (European Database for Multiple Sclerosis) presents EDSS
Updated: July 2015