Natural evolution of weight status in Duchenne muscular dystrophy: a retrospective audit

The life expectancy of patients with Duchenne muscular dystrophy (DMD) has increased. A cross-sectional study of DMD patients showed that 54% of 13-year-old patients are obese and that 54% of 18-year-old patients are underweight. We aimed to describe the natural evolution of weight status in DMD. This retrospective multi-centre audit collected body-weight measurements for seventy DMD patients born before 1992. The body-weight;age ratio (W:A) was used to evaluate weight status in reference to the Griffiths and Edwards chart. At the age of 13 years, 73% were obese and 4% were underweight. At maximal follow-up (age 15-26 years, mean 18.3 (SD 2.3) years), 47% were obese and 34% were underweight. Obesity at the age of 13 years was associated with later obesity, whereas normal weight status and underweight in 13-year-old patients predicted later underweight. A W:A >= 151% in 13-year-old patients predicted later obesity, and a W:A <= 126.5% predicted later underweight. Our audit provides the first longitudinal information about the spontaneous outcome of weight status in DMD. Patients (13 years old) with a W:A >= 151% were more likely to become obese in late adolescence, but obesity prevented later underweight. These data suggest that mild obesity in 13-year-old DMD patients (W:A between 120 and 150 %) should not be discouraged because it prevents later underweight.