Abstract:
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Objective : To establish the test- retest reliability of DEXA measurements in patients with DMD. Background : DEXA measurements are frequently used as an outcome measure in therapeutic trials of DMD to document changes in lean body mass. There is no data available in the literature documenting the reliability of these measurements. Methods : We performed repeated DEXA measurements on a single day on two separate visits on 12 boys with DMD participating in clinical trials at our site. The measurements were made with instrumentation and software from the Lunar corporation, Madison WI. Results : Demographic data: Age 6.6 (sd 0.9), Height 114cm (sd 7.4) Weight 20.4 kg (sd 3.0) All patients were ambulatory at the time of testing. The Intra class correlations (ICC) for the measurements of DEXA total, DEXA Bone Mineral Content (BMC), DEXA Fat, and DEXA Lean Body Mass (LBM) were: Visit 1: DEXA Total 0.99, DEXA BMC 0.97, DEXA Fat 0.99 and DEXA LBM 0.97 Visit 2: DEXA Total 0.97, DEXA BMC 0.98, DEXA Fat 0.99 and DEXA LBM 0.91. Conclusions : All the ICC's were greater than .90 which denotes excellent reliability. This also allows for the calculations of the minimal clinically important difference for natural history studies and therapeutic trials.
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