valuable data, establishing basic phenotype under no fatigue challenge con- ditions that could be used in drug response profiling in mdx mice. A descrip- tion of the physical activity and drug response in both paradigms will be presented. doi:10.1016/j.nmd.2011.06.791 P1.32 Comparison of quantitative strength measures in boys with DMD: HHM vs. CQMS T. Duong a , A. Cnaan a , F. Hu a , R. Leshner b a Children’s National Medical Center, Genetic Medicine, Washington DC, United States; b Children’s National Medical Center, Neurology, Washing- ton DC, United States A primary outcome measurement for evaluating efficacy in clinical tri- als of Duchenne muscular dystrophy (DMD) is strength. Because of the challenges of measuring strength, the Cooperative International Neuro- muscular Research Group (CINRG) adapted a fixed system called the CINRG Quantitative Measurement System (CQMS). A non-fixed method is a Hand-Held Myometry (HHM) device, by Microfet. This study com- pared the intra and inter rater reliability of these two methods in order to assess which of the two quantitative muscle testing systems is more reli- able for future DMD clinical trials. This study design evaluated two devices in 4 muscle groups (knee extension (KE), knee flexion (KF), elbow flexion (EF), elbow extension (EE)). Each of 2 testing days included 2 sessions of randomized order of each of the 2 devices and a different clinical evaluator (CE) on each day. Muscle group testing was in a standardized sequential order. A total of 30 children with DMD were evaluated 8 times, 4 on each device, by a combination of 9 experienced clinical evaluators at 5 CINRG sites. A mixed effects model confirmed that fatigue was not a factor in strength assessments (p > .16 for fatigue in all muscle groups models). Inter-rater reliability was high in both devices (>.88). Intra-rater reliability showed more variation with the fol- lowing ranges across all CEs: KE CQMS (.81–99), HHM (.85–.97); KF CQMS (.72–94), HHM (.67–.93); EE CQMS (.83–1.0), HHM (.92–.99); EF CQMS (.92–.99), HHM (.82–99). Confidence bands around the loess regression lines showed CQMS to have less variability in the younger age group and less difference between measures in the older age group, 3:4 muscles. The study shows comparable inter-rater reliability and age-asso- ciated intra-rater reliability. Knee flexion had the least inter and intra- rater reliability while elbow flexion had the best reliability. These results may impact the experimental design and sample size calculations in future clinical trials. doi:10.1016/j.nmd.2011.06.792 P1.33 Disease progression observed in clinical outcome measures in placebo-treated patients with nonsense mutation dystrophinopathy E. Mercuri a , K. Bushby b , C. McDonald c , N. Goemans d , F. Muntoni e , B.T. Darras f , G.L. Elfring g , J. Barth g , A. Reha g , S.W. Peltz g a Department of Paediatric Neurology, Catholic University, Rome, Italy; b Institute of Human Genetics, Newcastle University, International Centre for Life, Newcastle upon Tyne, United Kingdom; c University of California Davis School of Medicine, Davis, United States; d University Hospitals Leuven, Leuven, Belgium; e Great Ormond Street Hospital, London, United Kingdom; f Children’s Hospital Boston and Harvard Medical School, Boston, United States; g PTC Therapeutics, South Plain- field, United States Dystrophinopathy is an X-linked rare disorder causing severe, progres- sive muscle loss and early death. In 13% of patients, the disease is caused by a nonsense mutation in the gene for dystrophin. An international, mul- ticenter, randomized, double-blind, placebo-controlled trial (Study 007) enrolled ambulatory males P5 yrs with nonsense mutation dystrophinop- athy. Placebo arm (N = 57) data provide insight into the natural history of nonsense mutation dystrophinopathy over the course of 48 weeks. Pla- cebo-treated patients [median (range) age = 8 (5–15) yr, corticosteroid use = 40/57 (70%), median (range) baseline 6-min walk distance (6MWD) = 354 (159–533) m] were evaluated. Median (range) duration of steroid use prior to randomization = 26.5 (8–112) months. Clinical assessments included 6MWD, timed function tests (supine to stand, 10- m run/walk, stair climb/descend), and patient/parent-reported accidental falls. Mean (SD) 6MWD declined from 360 (88) m at baseline to 317 (152) m at Week 48 [D = 43 (90) m], D = 42 (88) m for patients on ste- roids and D = 43 (98) m for patients not on steroids. Baseline 6MWD was positively correlated with change in 6MWD over 48 weeks (r = 0.44; p < 0.001). Mean (SD) changes in timed function tests from baseline to Week 48 were as follows: stand from supine increased from 11.5 (11.4) s to 14.6 (12.3) s, run/walk increased from 6.9 (2.8) s to 9.9 (8.4) s, stair climb increased from 6.0 (5.7) s to 10.8 (11.3) s, and stair des- cend increased from 5.5 (5.8) s to 9.6 (10.7) s. Mean (SD) daily falls increased from 0.54 (0.94) at baseline to 0.72 (1.28) at Week 48. Baseline 6MWD was positively correlated with change in 6MWD in this study. 6MWD, timed function tests, and patient/parent-reported accidental falls are sensitive to disease progression over 48 weeks and should be utilized as outcome measures in future, long-term clinical trials in ambulatory sub- jects with dystrophinopathy. doi:10.1016/j.nmd.2011.06.793 P1.34 Body mass index (BMI) and growth in Duchenne Muscular Dystrophy (DMD) M. Guglieri a , J. Smith a , M. Eagle a , E. Scott b , R. Griggs c , K. Bushby a a Newcastle University, Institute of Genetic Medicine, Newcastle upon Tyne, United Kingdom; b Muscular Dystrophy Campaign, London, United King- dom; c University of Rochester School of Medicine and Dentistry, Roches- ter, NY, United States BMI is commonly used to monitor growth and the extent of obesity, and has been suggested as a criteria for corticosteroid treatment modifi- cation in DMD. The aim of this study was to evaluate weight, height and BMI changes in DMD boys on steroids to better understand their variation. This might allow optimisation of clinical guidelines for the management of growth in DMD. Baseline (pre-steroids) and longitudi- nal, follow-up data from the North Star Clinical Network Database were analysed. Data were available for 163 cases with follow-up P10 months. All subjects were on corticosteroids; mean age of starting steroids was 6.2 years. Baseline data confirmed that DMD boys tend to be on the lower centiles for height (24/39 boys height 69th centile). Weight was mainly distributed within the 9th and the 91st centiles. 16/39 boys had a BMI >91st centile. No clear trends in annual BMI increase were observed. Fifity percent of the subjects showed annual increase of BMI > 1 and 21/163 > 4 at least once during follow up. Increase was not linear and substantial variability was observed within the population and in the same subject. Risk of obesity was higher in the population with higher baseline BMI. No significant differences were observed between different steroid regimes but different steroids could not be com- pared due to the small number of subjects on deflazacort. Weight gain seems to impact on the annual BMI increase more than deceleration in height. This study confirmed the high frequency of weight gain and height deceleration in DMD. Identification of risk factors, response to different steroids and regime can have an impact on patient management. Standard guidelines for the management of steroid treatment and side effects would help clinical practice and future clinical trials. This study underlines the importance of collecting systematic follow-up data and Abstracts / Neuromuscular Disorders 21 (2011) 639–751 651