The relationship between disability and disease activity
Guy's And St Thomas's Hospital, London
Magnetic Resonance Imaging (MRI) has been used as a method of investigation in MS since 1981. This method has also been used to assess disease activity because it can detect the development of new lesions and changes in existing lesions in the brain or spinal cord. This makes MRI particularly useful in measuring the effectiveness of any new treatment. Scans have been used to assess the effectiveness of beta interferon in a number of trials to date, and have shown a reduction in disease activity in treated patients.
Disability, on the other hand, and not disease activity as measured by MRI scans, is what matters to people with MS. However, assessment of disability in MS is extremely difficult, and none of the current clinical assessment methods are satisfactory. The Extended Disability Status Scale (EDSS) developed by Kurtzke 30 years ago has been the most widely used, despite its imperfections.
Quantitative analysis of cranial MRI scans showed, in many studies, little relationship between the total volume of lesions (lesion load) and the extent of disability as measured by the EDSS. The work at Guy's Hospital explores this apparent discrepancy.
As a development of this work, a new comprehensive disability scale (the Guy's Neurological Disability Scale or GNDS, now renamed the UKNDS) has been developed.
It is hoped that a combination of the new disability scale, advanced MRI acquisition techniques and improved imaging analysis methods will make the conduct of clinical therapeutic trials in MS much easier. This will provide investigators with more sensitive outcome measures to assess the effectiveness of the latest treatments for MS.
The published report of this work is now available:
Sharrack B, Hughes RAC.
The Guy's Neurological Disability Scale (GNDS): a new disability measure for multiple sclerosis.
Multiple Sclerosis 1999;5(4):223-233.
