MS Research Update: How reliable are biomarkers measured by multiple providers?

April 11, 2013 Angeli Mayadev, MD

Mobility issues secondary to strength, balance, and walking problems affect up to 80 percent of people with multiple sclerosis (MS). Providers and therapists use a variety of scales and tools to measure the extent of these issues such as:


  • The Berg Balance Scale (BBS) is a measure of balance that uses a 14-item scale and is scored based upon the results 0-56.
  • The 6-minute walk (6MW) is a measure of walking endurance.
  • Handheld Dynamometry (HHD) is a way to quantify manual muscle strength testing.


There is a lot of emerging research about “MS biomarkers,” which are values that look for ways to predict how patients will do in the future. The above tests are “physical biomarkers” of patient performance that may be able to be used as measures of disease state and change over time.


Often patients and clinicians are left wondering how accurate the results of these tests are. For instance, if provider A performs a functional test on a patient, will provider B get the same results if administering the same test to the same patient?


New research from a small study in Ireland addresses this issue in patients with MS. Five physical therapists and eight MS patients who were able to walk at least 10 meters participated in the study. Therapists worked in pairs to score participants balance and walking, but all scored the muscle strength tests. The group of people with MS divided into those able to walk without a device and those who needed an assistive device.


The results showed that results for BBS and 6MW scores were well-reliable among varied providers, but poorly reliable for the HHD. This may have been because of varied experience of use with HHD device (a limitation of the study), as well as fatigue because all the measurements were taken on the same day.


Reliability has to do with the quality of measurement and is the "consistency" or "repeatability" of measurements. The reliability of the test is based on both provider A and provider B getting reasonably similar results on the same test in the same patient. The between-rater reliability is important when different providers perform measurements, which is almost inevitable over the years, because the results can be used as physical markers of patient performance over time.


(Click here to read the full research article in the Spring 2013 International Journal of MS Care.)

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