T.P.1

Current trials in Duchenne muscular dystrophy (DMD) have focused on the distance traveled using the 6-min walk test (6MWT). As a primary efficacy outcome for clinical trials it can be quantified over a continuous scale. Limitations include a self-selected walking speed irrespective of encouragement and weakness predisposing to falls. We predicted that a monetary incentive of $50 could improve same-day 6MWT performance. Nine DMD boys (mean age 7.7) were instructed to walk quickly, not run. Encouragement was permitted throughout the test. Subjects were then stratified into an above or below 350 m group and randomly assigned to either the incentivized (IN) or non-incentivized (non-IN) group. A second 6MWT was completed after a rest period during which the following instructions were provided. The IN was told “If you walk faster on this repeat 6MWT you will receive $50. Remember to walk quickly and safely.” The non-IN were told “You are repeating the 6MWT and remember to walk quickly and safely.” The same evaluator conducted both tests, was blinded to group, and provided the same encouragement during each 6MWT. Current data is available in 9 boys, however data on a cohort of 36 will be presented. The boys in the IN (n = 5, mean age = 7.7) walked an average of 44 m (11%, max: 105 m) farther on the second 6MWT. The non-IN (n = 4, mean age = 7.6) walked an average of 5.1 m (2%, max: 16 m) farther. The increase in distance in IN was most distinct in the above 350 m (75 m or 17%) compared to the below 350 m (24 m or 7%) group. Our pilot data suggest that a financial incentive results in a measurable increase in within-day 6MWT distance in DMD. This variance is more pronounced in the above 350 m group which is the typical target for clinical trials. This data suggests that external motivators have a significant impact on the 6MWT and should be considered in the design and interpretation of clinical trials.