P.7.16 One year outcome assessment of young boys with DMD using the Bayley-III Scales of Infant and Toddler Development

Abstract

Clinical trials currently underway in Duchenne muscular dystrophy (DMD) almost always exclude infants and young boys because traditional outcome measures rely on cooperation. Despite this, it is well known that the pathogenesis of this progressive dystrophy starts in the first years of life. The Bayley-III Scales of Infant and Toddler Development (Bayley-III) have been validated in typically developing infants and children through age 42months and recently in a cohort of 24 infants and boys with DMD. Clinical evaluators at six centers were trained and certified to perform the Bayley-III testing. Fourteen of these infants were young enough (1.6±0.8years) to be tested using the Bayley-III at baseline, 6, and 12months later. Repeated measures analysis showed that cognitive and language comprehensive scores (normal 100±15) remained stable, albeit low across one year (88.2±9.7 and 81.5±7.2 at baseline and 89.6±9.2 and 83.5±9.2 at 1year). Fine motor scale scores (normal 10±0.3) while low at baseline (8.1±2.1), increased slightly over one year (8.9±2.4). However, gross motor scaled scores which were low at baseline (6.8±1.8) declined at six months (5.8±2.0) and declined further at 12months (5.5±1.9). We show that gross motor development can be reliably measured in infants and young boys with DMD across one year. We further demonstrate that, relative to their peers, these boys are loosing ground, even in the so-called "honeymoon period". We conclude that young boys with DMD can be tested across time and should be considered for clinical trials.