The term "benign MS" describes a course of MS where people continue to have low levels of disability some years after diagnosis. But the definition uses the EDSS scale (Expanded Disability Status Scale) which focusses on physical disabilities and does not take account of invisible symptoms. This means that a low EDSS score may not accurately reflect the impact that MS has on someone’s life.
To get a better idea of how invisible symptoms affect people with benign MS, researchers compared the rates of cognitive difficulties, depression and fatigue in people with benign and non-benign MS.
This Australian-lead study collected data from 786 people with MS seen at an MS clinic in the States.
Participants were assessed for EDSS and levels of cognitive difficulties, fatigue and depression.
The researchers found that despite having much less physical disability, fatigue and depression are as common in benign MS as they are in non-benign MS. In addition, approximately 4 out of 10 people with benign MS experience cognitive difficulties. The researchers conclude that only a very small number of people with MS will have a disease course without any visible or invisible symptoms and question the use of the term “benign MS”.
Although the EDSS score is routinely used in the clinic, it does not capture cognitive difficulties, fatigue, or depression. A more comprehensive assessment which takes account of visible and invisible symptoms will give a better idea of how MS affects people’s lives and ensure that they get the support they need to manage their MS. The researchers recommend further research into how people diagnosed with benign MS access health services and how their needs are supported.
Background
The term "benign MS" is used to describe a course of MS where people continue to have low levels of disability some years after diagnosis. Definitions vary, but the most common is an EDSS (Expanded Disability Status Scale) score of 3 or less 10 years after the first signs of MS. But the EDSS focusses on physical disabilities and does not take account of invisible symptoms such as cognitive (thinking) difficulties, fatigue or depression. This means that a low EDSS score may not accurately reflect the impact that MS has on someone’s life. People who meet the criteria for having benign MS will often say that it feels anything but benign.
To get a better idea of how invisible symptoms affect people with benign MS, researchers compared the rates of cognitive difficulties, depression and fatigue in people with benign and non-benign MS.
How this study was carried out
This Australian-lead study collected data from 786 people with MS seen at an MS clinic in the States. They were divided into three groups:
- benign MS – MS for 10 years or longer and EDSS 3 or less
- non-benign MS – MS for 10 years or longer and EDSS greater than 3
- early MS - MS for less than 10 years
All participants were assessed for EDSS, completed a comprehensive series of tests for cognition and filled in questionnaires to determine levels of fatigue (Fatigue Severity Scale) and depression (Beck’s Depression Inventory). Results from these tests were compared.
What was found?
Out of 796 participants, approximately 18% had benign MS, 20% had non-benign MS and 62% had early MS.
In the benign MS group, 38% had cognitive difficulties compared with 65% in the non-benign MS group. The group with early MS had levels of cognitive difficulties (37.5%) similar to those with benign MS. There was no difference in levels of fatigue experienced by benign and non-benign participants – approximately 77% in each group scored moderate to severe fatigue, levels which would be expected to have a significant effect on day-to-day life. There was no difference in levels of depression between the groups, in all three groups approximately 55% were rated as having depression.
What does it mean?
These results show that despite having much less physical disability (average EDSS score 2.0 for benign vs 6.5 for non-benign MS), fatigue and depression are as common in benign MS as they are in non-benign MS, affecting approximately 7 out 10 people in both groups. In addition, approximately 4 out of 10 people with benign MS also experience cognitive difficulties. This raises the question of how people with benign MS are coping in everyday life and how their MS affects employment, family and social life. The researchers conclude that only a very small number of people with MS will have a disease course which is without any visible or invisible symptoms and question the use of the term “benign MS”.
The study highlights the importance of invisible symptoms in people with MS who may appear to have no physical disability. Although the EDSS score is routinely used in the clinic, it does not capture cognitive difficulties, fatigue, or depression. A more comprehensive assessment using tests which take account of visible and invisible symptoms will give a better idea of how MS affects people’s lives and ensure that they get the support they need to manage their MS.
The investigators consider that further research is needed into how people diagnosed with benign MS access health services and how their needs are supported.
Bogaardt H, et al.
Cognitive impairment, fatigue and depression in multiple sclerosis: Is there a difference between benign and non-benign MS?
Mult Scler Relat Disord. 2023 Mar 21; 73: 104630.
Summary
Full article
Exact definitions for benign MS vary, but the most common definition of benign MS is an EDSS (Expanded Disability Status Scale) score of 3 or less, 10 years after the first signs of MS.
An EDSS score of 3 is associated with moderate problems with one symptom or mild problems with several with walking unaffected. Since the defining characteristic of benign MS is the long-term absence of symptoms, it can only be diagnosed retrospectively after ten or more years. The term should be used with caution and can only describe someone's past experience of MS.
EDSS - Expanded Disability Status Scale - is the tool that neurologists and other health professionals use to measure disability in people with MS and monitor changes over time. It is widely used in clinical trials and for annual assessments of people with MS.
The EDSS scale ranges from 0 to 10 in 0.5 unit increments that represent higher levels of disability. Scoring is based on an examination by a neurologist.
EDSS steps 1.0 to 4.5 refer to people with MS who are able to walk without any aid and is based on measures of problems with weakness, co-ordination, speech and swallowing, numbness, bowel and bladder function and eyesight. EDSS steps 5.0 to 9.5 are defined by impairment to walking.
EDSS is sometimes criticised for a number of reasons. Firstly, because people’s MS symptoms vary from day to day, they may get an EDSS score reflecting how they were at the time when they were assessed – which may or may not be typical.
EDSS also measures disability primarily by the mobility of the person with MS. For example, EDSS 4 is defined as someone able to walk 500m without aid or rest, while at EDSS 6 they require a walking aid, such as a cane or crutch to walk about 100m, with or without resting. Some neurologists have noted that this doesn’t measure how MS affects upper limb mobility, for example.
If you want to know more about your EDSS score and what it means for you, speak to your neurologist or MS nurse. You can also try working out your EDSS for yourself by using the online EDSS calculator developed by the MS Team at Barts Hospital in London.
