SaGAS 20/10 is a simple, valid and sensitive iPhone app that appears as an alternative to the Multiple Sclerosis Functional Composite (MSFC) and as a most welcome complement to the Expanded Disability Status Scale (EDSS) for the moderately disabled Multiple sclerosis (MS) patients where the gold standard fails to assess the patients comprehensively. But it could be also used for any other neurological disease where walking and hand function are impaired.
Multiple sclerosis (MS) is a common, progressive not yet curable disabling neurological disorder. Disability increases steadily over time, limiting, in many patients, not only ambulation but also manual dexterity. Many substances have been shown to reduce exacerbation rate and disease progression in some patients. The efficacy of these costly drugs should ideally be evaluated with reliable, valid and sensitive assessment tools.
Hence the need for an assessment tool such as the Short and Graphic Ability Score (SaGAS 20/10) which is based on the motor components of the MSFC, that considers hand function separately and that can be expressed using a clearly defined, clinically relevant interval scoring system.
SaGAS 20/10 is composed by 3 measures: the 25 feet timed walk at fast speed with a flying start (T25FW) and the nine-hole peg test (9-HPT) of each hand separately. The timed performances (t) of these 3 measures can be expressed as a logarithmic function of time in three (sS) subscores that are constructed in such a way that any interval of 0.9/respectively 1.1 units corresponds to a change of 20%, considered as clinically meaningful.** Because of mathematical reasons explained in our initial paper in 2004 improvements need a change of 1.1 points, whereas as 0.9 reflects a significant deterioration.*
(T25FWsS)
T25FW subscore = 20-11.474 x log (4/t);
a walking time of 4 seconds corresponding to a maximum T25FWsS of 20.
(9-HPTsS)
9HPT subscore = 10-11.474 x log (20/t);
a performance of 20 seconds in 9HPT corresponding to a maximum NHPTsS of 10.
SaGAS 20/10 is computed:
(T25FWsS + NHPTsS right hand + NHPTsS left hand)/2.
A healthy person would hence score: (20 +10 +10) /2 = 20
The 3 subscores can be displayed graphically as a Vitruvian Man on an IPhone app.
References:
* Kragt JJ et al. Clinical impact of 20% worsening on Timed 25-foot Walk and 9-hole Peg Test in multiple sclerosis Mult Scler September 2006 12: 594-98.
** Vaney C, Vaney S. and Wade DT. SaGAS, the Short and Graphic Ability Score: an alternative scoring method for the motor components of the Multiple Sclerosis Functional Composite. 2004 Mult Scler April;10(2):231-42.