title: Ambulatory capacity and disease progression as measured by the 6-minute-walk-distance in Duchenne muscular dystrophy subjects on daily corticosteroids.
abstract: In order to understand contemporary natural history of Duchenne muscular dystrophy (DMD), we report 6-minute walk distance (6MWD) and its change over time from a large single centre population of corticosteroid treated DMD boys. Sixty-five boys on daily corticosteroid treatment were identified with a mean (SD) age of 9.5 (2.3) years at first observation. 6MWD was described for 1year age groupings. In addition, changes in 6MWD at 1, 1.5 and 2years (±12weeks) of follow-up were evaluated. The same evaluations were applied to 6MWD data converted to percent predicted values based on the Geiger equation. 6MWD showed an increase from age group 4.5-5.5years to age group 6.5-7.5years, followed by a decline, which became precipitous from 12.5years onwards. From 15.5years, all boys were unable to perform the 6-min test. Changes in 6MWD demonstrated a mean (median, SD) decline of -43 (-14, 90) m at 1year (N=25, mean baseline age 9.5years), -64 (-56, 99) m at 1.5years (N=18, mean baseline age 9.6years), -125 (-106, 139) m at 2years (N=14, mean baseline age 10.0years). Conversion to percent predicted values showed the same pattern of evolution.This study provides data on the ambulatory capacity and its changes over time in a homogenous cohort of 65 DMD boys on daily corticosteroids. The variability, the age-related aspects and the slope of decline of the 6MWD should be considered in the design and interpretation of therapeutic trials in ambulant DMD patients.
authors.affiliation: Child Neurology, University Hospitals Leuven, Leuven, Belgium. nathalie.goemans@uzleuven.be
authors.forename: Nathalie
authors.initials: N
authors.lastname: Goemans
authors.forename: Marleen
authors.initials: M
authors.lastname: van den Hauwe
authors.forename: Rosamund
authors.initials: R
authors.lastname: Wilson
authors.forename: Annelies
authors.initials: A
authors.lastname: van Impe
authors.forename: Katrijn
authors.initials: K
authors.lastname: Klingels
authors.forename: Gunnar
authors.initials: G
authors.lastname: Buyse
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D005080:Exercise Test; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000188:drug therapy* / Q000503:physiopathology*; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D000305:Adrenal Cortex Hormones
keywords: 6-Min walk test; Ambulatory capacity; Corticosteroids; Disease evolution; Duchenne muscular dystrophy; Variability