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

BACKGROUND: Mobility 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.

OBJECTIVE: To investigate sensitivity and specificity of the TTW and T25FW to detect mild clinical impairment in a large cohort of MS patients.

METHODS: We 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.

RESULTS: Between 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.

CONCLUSION: A 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.