SaGAS, the Short and Graphic Ability Score: an alternative scoring method for the motor components of the Multiple Sclerosis Functional Composite.

The timed performances of the 10-m timed walk (TMTW) and the nine-hole peg test (NHPT) of 881 consecutive patients with multiple sclerosis (MS) undergoing a rehabilitation stay, were expressed as a logarithmic function of time in two subscores to form a composite score called the Short and Graphic Ability Score (SaGAS). The subscores (sS) were constructed in such a way that any interval of 0.5 unit corresponds to a change of 25% in the tests. The SaGAS was computed as the mean of four subscores: SaGAS = (2 x TMTWsS + NHPTsS right hand + NHPTsS left hand). With the aid of a nomogram, the timed values of the tests are easily transformed into the corresponding subscores, which are then displayed graphically to facilitate follow-up over time. The correlation coefficients between the SaGAS and the two motor components of the MS Functional Composite (MSFC) (r = 0.987), the Expanded Disability Status Scale (EDSS)(r = -0.83), the Nottingham EADL Index (r = 0.80) and the Rivermead Mobility Index (RMI) (r = 0.90) were all statistically significant (P < 0.001), supporting the validity of the measure. SaGAS had a similar sensitivity to the RMI, but was significantly more sensitive than the EDSS in detecting changes occurring during the rehabilitation stay (14.9% versus 5.0%; P < 0.001) and over a one-year follow-up (35.3% versus 19.7%; P < 0.001). Compared with the motor components of the MSFC, with which it shares several features, SaGAS has several advantages: it does not depend on the stratification of the study population; it does not skew the results of the NHPT towards improvement at the lower end; and it offers an independent assessment of both hands. SaGAS is a simple, intuitive, nonphysician-based measure, which could provide consistent scoring in future clinical trials.