A 3 meter Timed Tandem Walk is an early marker of motor and cerebellar impairment in fully ambulatory MS patients

Abstract

BackgroundMobility assessment in Multiple Sclerosis (MS) is crucial for trials and individual patient counseling. Up to now, standard tests as the Timed 25-Foot Walk (T25FW) are restricted by floor effects in mildly disabled patients. The 3-meter Timed Tandem Walk (TTW) as a possibly more sensitive measure has not been investigated yet. ObjectiveTo investigate sensitivity and specificity of the TTW and T25FW to detect mild clinical impairment in a large cohort of MS patients. MethodsWe extracted T25FW, TTW and EDSS from our UMC patient database (2009–2012). After randomization into an explorative (n=497) and validation (n=228) cohort, we calculated change rates and performed ROC analyses of gait tests and EDSS including Functional System Scores. ResultsBetween disability stages of EDSS 0–2.5 and EDSS 3.0–4.0, the mean TTW difference was 4s (T25FW=0.9s). The accuracy to separate between EDSS groups was moderate but identical for both tests (ROC–AUC T25FW=0.79, TTW=0.80, p=0.4). TTW had a higher sensitivity and specificity to differentiate between asymptomatic and symptomatic patients concerning FS motor/cerebellar scores (ROC–AUC T25FW=0.71, TTW=0.75, p<0.05). All hypotheses could be validated in the second cohort. ConclusionA 3-m Timed Tandem Walk is a standardized test that is easy to implement to detect impairment of the motor or cerebellar system in fully ambulatory MS patients. Based on the complex-task character, TTW is a potential new outcome measure for MS mobility in mildly disabled patients and can act as easily accessible and significant additional information in patient counseling.