Multiple sclerosis can cause symptoms in virtually every part of your body — visual problems, cognitive issues, numbness, weakness, and bowel and bladder issues — all of which can lower your quality of life. For people with relapsing-remitting multiple sclerosis, these problems come in waves. Those with primary progressive multiple sclerosis or secondary progressive multiple sclerosis experience slowly worsening symptoms over time.
If MS can affect people in very different ways, how are doctors able to accurately track the clinical course of a person’s unique diagnosis? Neurologists and other health care professionals use the Kurtzke Expanded Disability Status Scale to track disability progression.
This article will cover the basics of the EDSS, including:
The EDSS offers a way to measure how much your MS affects you now. It was developed in the 1980s from a dataset of several hundred people with MS. A person’s disease progression is tracked with a score from 0 to 10. A score of 0 means a person has no disability, and a score of 10 indicates death from MS. The higher the score, the more negatively a person is affected by MS. Points are assigned by your doctor after they examine you and ask about how MS has been affecting your life since your previous visit.
The EDSS is largely used for research and clinical trials to track how certain treatments affect disability progression in MS. However, it is also used as a clinical tool to see whether or not people living with MS are improving over time. Additionally, the EDSS can be used as one of many predictors of how well you might do going forward.
MS can affect any part of your central nervous system (CNS) — your brain and spinal cord — both of which control a wide range of functions. Thus, to calculate your EDSS score, your neurologist will look at various functional systems to see how they have been impacted by MS, if at all. These functions include:
The scale progresses in half-point increments from 0 through 10 (0, 0.5, 1.0, 1.5, etc.). Here is a summary of what some of the ranges and individual numbers roughly mean:
The EDSS is not a perfect measure of the impact of MS for three main reasons.
Most of the EDSS centers around mobility. However, living with MS involves much more than just your ability to stand, walk, and run. There are invisible symptoms that are no less a reality for people affected by MS, including:
The EDSS scale also ignores brain and body scans, another marker of disability. For example, radiologists track certain lesions in the brain and whether or not those lesions are “gadolinium-enhancing” — meaning they light up on scans when exposed to gadolinium-based contrast. This is used as a marker for MS activity and disease duration.
Learn more about MS Flare-Ups and Managing Relapses.
The EDSS is not a way to diagnose MS. There are other criteria (called the McDonald criteria) that neurologists use to make this diagnosis. These criteria include symptoms as well as findings on scans such as MRI.
The scale is not linear. This means, for example, that a score increase from 1.0 to 1.5 does not reflect the same amount of change in disease progression as a score increase from 8.0 to 8.5. An increase from 1.0 to 1.5 indicates very minor changes, whereas moving from 8.0 to 8.5 can indicate a significant change — that a person has gone from being able to use a wheelchair throughout the day to being essentially bedridden. This can be a point of confusion for many people — even in MS and neuroscience research, where changes in EDSS scores are often measured as raw numbers.
Given the aforementioned shortcomings, you may wonder why the EDSS and similar scales are even necessary. Can’t the doctor just ask about and write down a person’s symptoms to track the progression of their condition?
Doctors rely on a medical history and what they find through physical exams to assess disease activity. However, many of these findings can be very subjective, as much is based on the doctor’s personal interpretation. One doctor might think a person has a rating of 3 out of 5 in arm strength, while another may think the person’s arm strength should be rated 4 out of 5.
The EDSS and other scales try to solve this problem by turning this process into an objective one with consistent scores. By assigning numbers and clearly defining what each number means in a standard rubric, the EDSS tries to decrease bias between different raters. The result, though imperfect, has value.
Take the quiz: Is My MS Progressing?
Many disease-modifying therapies have not been available for people above or below a certain EDSS score cutoff, largely because many clinical trials and study groups will only include people in a certain score range in their testing.
Follow up with your doctor and other medical professionals regularly as scheduled, and let them know exactly how MS affects you. Tell them how you were at your baseline (when you were first diagnosed) compared to how you are now.
The EDSS and other scales are not perfect tools, and they often focus on only certain parts of the MS experience. That’s why it is important to tell your doctor about both the visible and invisible parts of your own experience.
MyMSTeam is the social network for people with multiple sclerosis and their loved ones. On MyMSTeam, more than 170,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.
Do you have questions about the EDSS or what it means? Share your experience in the comments below, or start a conversation by posting on MyMSTeam.