T.P.4: Long term natural history data in ambulant boys with Duchenne muscular dystrophy: 36 month changes

The 6 min walk test (6MWT) has been recently chosen as the primary outcome measure in several international multicenter clinical trials in Duchenne muscular dystrophy (DMD) ambulant patients. The aim of the study was to assess the spectrum of changes at 3 years in the individual measures, their correlation with steroid treatment and with age and 6MWT values at baseline. 96 patients from 11 centers were assessed at baseline and 1, 2 and 3 years after baseline. Three boys (3%) lost the ability to perform the test within 12 months, another 13 between 12 and 24 months (14%) and other 11 between 24 and 36 months (12%). The 6MWT showed an average overall decline of −15.8 (SD 77.3) meters in the first year, of −58.9 (SD 125.7) in the second year and −104.22 (SD 146.2) in the third year. The changes were significantly different in the two baseline age groups and according to the baseline 6MWT values (below and above 350 m) (test for interaction, p p for interaction = 0.01). These results can be of help at the time of using inclusion criteria for a study in ambulant patients in order to minimize the risk of patients who may lose ambulation within the time of the trial.