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Questionnaire helps clinicians track the progression of a rare disease that weakens muscles.
Posted On: September 14, 2016
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Although myasthenia gravis can lead to weakening of any voluntary muscle, the muscles that control the eye, eyelid, facial expressions and swallowing (pictured) are frequently affected.
Myasthenia gravis (MG) is a disease caused by the gradual breakdown of communication between nerves and muscles. This breakdown leads to varying degrees of weakness in the body’s muscles, which worsens during periods of activity and improves after periods of rest.
An interesting aspect of MG is that treatments—ranging from medication to surgery—vary depending on the severity of symptoms. However, measuring disease severity remains a challenge because some symptoms are only triggered by activities that are not easily observed in the clinic.
In order to improve disease tracking, University of Toronto Assistant Professor Dr. Carolina Barnett Tapia, working with Krembil Senior Scientist Dr. Aileen Davis, set out to develop a questionnaire that could be used by clinicians to more reliably assess disease stage. The original draft of the questionnaire was assembled using common examination questions taken from the MG literature and provided by various MG experts. Then, the study team asked 18 MG patients and 72 MG experts for their input on what questions should be changed, removed or added in order to improve comprehension and diagnostic accuracy.
The team tested the revised questionnaire on 200 individuals with MG. The results revealed that the questionnaire excelled in two important ways: reliability and accuracy. Specifically, they found that the questionnaire yielded similar scores when administered to the same patient on separate occasions (known as the “test–retest reliability”). They also found that the questionnaire was a good indicator of actual disease state (known as “construct validity”).
“Overall, the main advantages of our questionnaire are that it is easy to use, does not take long to complete and, at the same time, provides a comprehensive assessment of the myasthenic state in patients,” says Dr. Davis.
This work was supported by the American Academy of Neurology, the American Brain Foundation and the Toronto General & Western Hospital Foundation.
Development and validation of the Myasthenia Gravis Impairment Index. Barnett C, Bril V, Kapral M, Kulkarni A, Davis AM. Neurology. PMID: 27402891. 2016 Jul 8. [Pubmed abstract]
An interesting aspect of MG is that treatments—ranging from medication to surgery—vary depending on the severity of symptoms. However, measuring disease severity remains a challenge because some symptoms are only triggered by activities that are not easily observed in the clinic.
In order to improve disease tracking, University of Toronto Assistant Professor Dr. Carolina Barnett Tapia, working with Krembil Senior Scientist Dr. Aileen Davis, set out to develop a questionnaire that could be used by clinicians to more reliably assess disease stage. The original draft of the questionnaire was assembled using common examination questions taken from the MG literature and provided by various MG experts. Then, the study team asked 18 MG patients and 72 MG experts for their input on what questions should be changed, removed or added in order to improve comprehension and diagnostic accuracy.
The team tested the revised questionnaire on 200 individuals with MG. The results revealed that the questionnaire excelled in two important ways: reliability and accuracy. Specifically, they found that the questionnaire yielded similar scores when administered to the same patient on separate occasions (known as the “test–retest reliability”). They also found that the questionnaire was a good indicator of actual disease state (known as “construct validity”).
“Overall, the main advantages of our questionnaire are that it is easy to use, does not take long to complete and, at the same time, provides a comprehensive assessment of the myasthenic state in patients,” says Dr. Davis.
This work was supported by the American Academy of Neurology, the American Brain Foundation and the Toronto General & Western Hospital Foundation.
Development and validation of the Myasthenia Gravis Impairment Index. Barnett C, Bril V, Kapral M, Kulkarni A, Davis AM. Neurology. PMID: 27402891. 2016 Jul 8. [Pubmed abstract]