Lower Extremity Functional Outcome Measures in Duchenne Muscular Dystrophy-A Delphi Survey

Background: Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease characterized by progressive muscle weakness, multiple system involvement and premature mortality. Effective treatments for DMD through clinical trials and natural history studies are currently underway. Clinical trials in DMD typically include several outcome measures of motor function. Research sites and studies have been found to have slightly different operational definitions for a given functional outcome resulting in different procedures and protocols for these measurements.

Objective: The goal of this study is to establish agreement among experts in the field around best practices in collecting functional outcome data in DMD providing researchers and clinicians with guidance on best practices.

Methods: A group of 30 experts in Duchenne Muscular Dystrophy (DMD) with experience in the development and/ or execution of lower extremity outcome measures for this population met face to face to identify incongruences in the collection of this data. This effort was based in the United States (US) and sponsored by Parent Project Muscular Dystrophy. Several discrepancies were categorized for each outcome which included: 6-minute walk test, 10-meter walk/run, supine to stand, ascend 4 stairs, sit to stand, and the NorthStar Ambulatory Assessment. Following this meeting an additional 32 experts in DMD (28 from the United States and 11 international participants) consented to participate in a Delphi Survey to reach consensus on the protocols and execution of lower extremity outcomes.

Results: Round one: 70 operationally defined questions were surveyed with 45 (64%) reaching >70% consensus. Round two: 27 questions were operational, with 20 (74%) reaching >70% consensus. Those questions that did not reach consensus appear minor.

Conclusion: With minor modifications in the collection of data across sites, outcomes could potentially be normalized across research studies. This would reduce excessive training for evaluators in trials and produce minimal differences between protocols. Consistency in protocols will promote more efficient study start up, less errors between administration of items across studies, and ultimately improve quality and reliability of the functional outcomes. The authors strongly advocate for the establishment of a “research network library” that could be utilized by all those performing clinical assessments and trials in DMD.

Keywords: Delphi survey; Duchenne muscular dystrophy; OutcomesDMD; consensus; lower extremity; outcome measures; research network library.