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MS information for health and social care professionals Clinical measures

Measurement of a condition as variable as MS is notoriously difficult but the need for evidencebased decisions has highlighted the importance of the development of adequate measures[1]. For any measure to be acceptable it must be reliable, reproducible and valid. Reliability concerns the extent to which scores produced by a scale are free from measurement error and able to be reproduced, whilst validity concerns the extent to which an instrument is measuring what was intended. In the field of health another parameter is also necessary: whether the measure can detect clinical change in the attribute being measured even if the change is small. This property is termed responsiveness.

Clinically useful scales therefore:

  • reflect the extent of the disease process
  • are multi-dimensional to reflect the main ways in which the disease affects an individual
  • are scientifically sound
  • are capable of reflecting change over time.

A further consideration is also necessary. Are the aspects of life considered important by the person with MS the same as those which the clinician considers important? There is increasing recognition that these two viewpoints can be quite different and thus the choice of measurement should be given careful consideration depending on the requirement of the outcome[2]. NICE made no recommendation regarding outcome measures, recognising the need for careful choice of measures to reflect change in different situations and from different perspectives.

Scales to monitor impairment:

  • The most frequently used scale for the assessment of MS has been Kurtzke's Expanded Disability Status Scale (EDSS). This is an observer-rated scale, usually performed by a neurologist. It addresses impairment in its lower levels and mobility in its higher levels. It is of limited reliability and poor responsiveness with a bias towards physical (especially ambulatory) rather than cognitive effects. It is not a linear scale and people with MS spend more time at some levels on the scale than others. Despite its limitations this is the most widely used impairment assessment scale in MS particularly in clinical trials.
  • The Scripps Neurological Rating Scale is based on the standard neurological examination with an extra category for bladder, bowel and sexual dysfunction. Correlation between the Scripps scale and EDSS is not good and further psychometric evaluation is necessary.

Scales to monitor a person's need for care:

  • The Extended Barthel Index is well-established, monitoring ten areas of activities of daily living: bowel, bladder, grooming, toilet use, feeding, transfer, mobility, dressing, stairs, and bathing on 0- 3 point scales. It does not however include cognition or communication.
  • The Functional Independence Measure (FIM) is more detailed than the Barthel scale in that it includes an assessment of communication and social cognition and uses 1-7 point rating scales.

Health Status Scales:

All the scales listed in this section are questionnaires and would be completed by the person with MS following an introduction from a health professional.

  • The Multiple Sclerosis Impact Scale (MSIS-29) measures 20 physical and 9 psychological items assessing how much impact they have on life from the patient's perspective. This combines both quality of life issues and psychometric testing.
  • The Medical Outcome Study Short Form 36 Health Survey (SF36) measures the health status in eight dimensions including physical function, pain, general health, vitality, and social functioning. This scale is widely used but because it is not MS specific, its usefulness can be limited.However this can compare the impact of MS with other conditions.
  • The MS Quality of Life Instrument (MSQOL 54) is a variant of the SF36 with an additional 18 items that are specific to MS.
  • MS Quality of Life Inventory (MSQLI) is composed of SF36 plus pre-existing established symptom related scales, this allows comparisons of specific symptoms across subject samples and with other illness groups.
  • The Functional Assessment of Multiple Sclerosis quality of life instrument (FAMS) is based on a scale developed within the oncology environment.
  • The Leeds MS Quality of Life Scale (LMSQoL) is a recent development and again is MS specific.
  • The UK Neurological Disability Scale, formerly known as the Guys Neurological Disability Scale (UKNDS/GNDS) is based on 12 areas which are considered important by neurologists. This captures many aspects of disabilities that can be experienced by people with MS and is commonly used by health professionals in practice as a basis for assessment.

Mobility Scales:

  • The A1 scale is similar to EDSS but gives a more precise measure within levels 4 - 6.
  • The ten metre timed walk.
  • Rivermead Mobility scale covers mobility, including bed mobility, lying to sitting, transfer and gait.

Upper Limb Function:

  • Nine hole peg test
  • Box and block.

Both are tests of manual dexterity with the former requiring greater dexterity. Both are commercially available, simple and can be administered in less than 10 minutes.

Spasticity scales:

  • The Ashworth scale is most frequently used with a clinical rating being given after an assessor tests the passive resistance to passive movement of a joint. A physiotherapist would normally administer this scale.

Cognition scales:

  • Paced Auditory Serial Addition Test (PASAT). Two variations of this test are used: a 2 or 3 minute version.
  • Symbol-digit modalities test (SDMT). Both these cognition tests need to be administered by trained personnel.

Composite assessment scores:

The complexity of the disease and the range of measures available have now led to research with the aim of validating composite measures which encompass the major clinical dimensions that are of relevance both to the clinician and to the person with MS.

  • The MS Functional Composite is a recently evaluated example. This involves:
    1. Timed walk of 25ft
    2. Nine hole peg test
    3. PASAT 3 minute version

    Each of the test results is standardised using a reference population and the resulting scores are averaged to provide a single score.

References

  1. Thompson AJ, Hobart JC. Multiple sclerosis: assessment of disability and disability scales. J Neurol 1998;245:189- 96.
  2. Rothwell PM, McDowell Z, Wong CK, et al. Doctors and patients don't agree: cross sectional study of patients' and doctors' perceptions and assessments of disability in multiple sclerosis. BMJ 1997;314(7094):1580-83.