THE 6-MINUTE WALK TEST AND OTHER ENDPOINTS IN DUCHENNE MUSCULAR DYSTROPHY: LONGITUDINAL NATURAL HISTORY OBSERVATIONS OVER 48 WEEKS FROM A MULTICENTER STUDY

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Abstract

Introduction: Duchenne muscular dystrophy (DMD) subjects ≥5 years with nonsense mutations were followed for 48 weeks in a multicenter, randomized, double-blind, placebo-controlled trial of ataluren. Placebo arm data ( N = 57) provided insight into the natural history of the 6-minute walk test (6MWT) and other endpoints. Methods: Evaluations performed every 6 weeks included the 6-minute walk distance (6MWD), timed function tests (TFTs), and quantitative strength using hand-held myometry. Results: Baseline age (≥7 years), 6MWD, and selected TFT performance are strong predictors of decline in ambulation (Δ6MWD) and time to 10% worsening in 6MWD. A baseline 6MWD of <350 meters was associated with greater functional decline, and loss of ambulation was only seen in those with baseline 6MWD <325 meters. Only 1 of 42 (2.3%) subjects able to stand from supine lost ambulation. Conclusion: Findings confirm the clinical meaningfulness of the 6MWD as the most accepted primary clinical endpoint in ambulatory DMD trials.

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Six-minute walk test in children and adolescents.

Leah I. Stein, Benedikt Treml, Ralf Geiger … (2007)

To evaluate the 6-minute walking distance (6MWD) for healthy Caucasian children and adolescents of a population-based sample from the age of 3 to 18 years. Two hundred and eighty boys and 248 girls completed a modified test, using a measuring wheel as incentive device. Median 6MWD increased from the age of 3 to 11 years in boys and girls alike and increased further with increasing age in boys (from 667.3 m to 727.6 m), whereas it essentially plateaued in girls (655.8 m to 660.9 m). After adjusting for age, height (P = .001 in boys and P < .001 in girls) remained independently correlated with the 6MWD. In the best fitting and most efficient linear and quadratic regression models, the variables age and height explained about 49% of the variability of the 6MWD in boys and 50% in girls. This modified 6-minute walk test (6MWT) proved to be safe, easy to perform, and highly acceptable to children. It provides a simple and inexpensive means to measure functional exercise capacity in children, even of young age, and might be of value when conducting comparable studies.

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Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of life.

Simon Tierney, Kathleen Wyrwich, Christoph Nienaber … (1999)

To compare the standard error of measurement (SEM) with established standards for clinically relevant intra-individual change in an evaluation of health-related quality of life. Secondary analysis of data from a randomized controlled trial. Six hundred and five outpatients with a history of cardiac problems attending the general medicine clinics of a major academic medical center. Baseline and follow-up interviews included a modified version of the Chronic Heart Failure Questionnaire (CHQ) and the SF-36. The SEM values corresponding to established standards for minimal clinically important differences (MCIDs) on the CHQ were determined. Individual change on the SF-36 was explored using the same SEM criterion. One-SEM changes in this population corresponded well to the patient-driven MCID standards on all CHQ dimensions (weighted kappas (0.87; P < 0.001). The distributions of outpatients who improved, remained stable, or declined (defined by the one-SEM criterion) were generally consistent between CHQ dimensions and SF-36 subscales. The use of the SEM to evaluate individual patient change should be explored among other health-related quality of life instruments with established standards for clinically relevant differences. Only then can it be determined whether the one-SEM criterion can be consistently applied as a proxy for clinically meaningful change.

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Combining distribution- and anchor-based approaches to determine minimally important differences: the FACIT experience.

Kathleen Yost, David Eton (2005)

Health-related quality of life (HRQOL) is an important endpoint in cancer clinical trials and in cancer treatment in general; however, the meaningfulness of HRQOL scores may not be apparent to clinicians or researchers. Minimally important differences (MIDs) can enhance the interpretability of HRQOL scores by identifying differences likely to be meaningful to patients and clinicians. This article's objective is to describe and provide examples of approaches we have used to identify MIDs for instruments in the Functional Assessment of Chronic Illness Therapy (FACIT) measurement system. Distribution- and anchor-based approaches are described and illustrated. We also discuss the importance of assessing the appropriateness of anchors, and we provide suggestions for combining results into a single range of plausible MIDs. MIDs for FACIT instruments established to date are summarized, and general guidelines that can be used to estimate MIDs for other FACIT instruments are provided. Applications of MIDs in research are illustrated.

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Author and article information

Journal

Journal ID (nlm-ta): Muscle Nerve

Journal ID (iso-abbrev): Muscle Nerve

Journal ID (publisher-id): mus

Title: Muscle & Nerve

Publisher: Blackwell Publishing Ltd

ISSN (Print): 0148-639X

ISSN (Electronic): 1097-4598

Publication date (Print): September 2013

Publication date (Electronic): 26 June 2013

Volume: 48

Issue: 3

Pages: 343-356

Affiliations

[1 ]Department of Physical Medicine and Rehabilitation, University of California Davis School of Medicine Davis, California, 95817, USA

[2 ]Department of Neurology, Washington University School of Medicine St. Louis, Missouri, USA

[3 ]Institute of Genetic Medicine, Newcastle University Newcastle upon Tyne, UK

[4 ]Department of Physical Therapy, University of Utah School of Medicine Salt Lake City, Utah, USA

[5 ]Department of Physical Therapy, Children's Hospital of Philadelphia Philadelphia, Pennsylvania, USA

[6 ]PTC Therapeutics, South Plainfield NJ, USA

Author notes

Correspondence to: C.M. McDonald; e-mail: cmmcdonald@ 123456ucdavis.edu

[*]

Collaborating authors and members of the PTC124-GD-007-DMD Study Group are listed in Appendix 1.

Disclosures: C.M.M is a member of the Cooperative Neuromuscular Research Group (CINRG) executive committee and has served on advisory committees for PTC Therapeutics, Inc., Sarepta Therapeutics, Inc., GlaxoSmithKline, Prosensa, Halo Therapeutics, Shire HGT, Cardero Therapeutics, and Novartis AG. E.K.H. is a member of the CINRG executive committee and has served as a consultant for Genzyme Corporation and PTC Therapeutics, Inc. R.T.A. served as a consultant for PTC Therapeutics, Inc., and Sarepta Therapeutics. J.M.F. serves on a scientific advisory board for Prosensa, the editorial board of Neuromuscular Disorders, and is a member of the CINRG executive committee and a consultant for Prosensa, GlaxoSmithKline, Genzyme Corporation, PTC Therapeutics, Inc., and Acceleron Pharma. M.E. has served as a clinical evaluator trainer for PTC Therapeutics, Inc., and as a consultant for Prosensa, and GlaxoSmithKline. E.G. has served as a clinical evaluator trainer for PTC Therapeutics, Inc. A.M.G. has served as a clinical evaluator trainer for PTC Therapeutics, Inc.. R.S. is the Chief Medical Officer for PTC Therapeutics, Inc. J.B. is the Vice President for Clinical Development at PTC Therapeutics, Inc.. G.E. is Executive Director of Biostatistics at PTC Therapeutics, Inc. A.R. is the Director of Clinical Development at PTC Therapeutics, Inc. S.P. is the Chief Executive Officer and a founding scientist at PTC Therapeutics, Inc.

Article

DOI: 10.1002/mus.23902

PMC ID: 3824082

PubMed ID: 23681930

SO-VID: da3141cd-3e3d-4761-b574-2a8fcd3850a8

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Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.

THE 6-MINUTE WALK TEST AND OTHER ENDPOINTS IN DUCHENNE MUSCULAR DYSTROPHY: LONGITUDINAL NATURAL HISTORY OBSERVATIONS OVER 48 WEEKS FROM A MULTICENTER STUDY

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Most cited references 33

Six-minute walk test in children and adolescents.

Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of life.

Combining distribution- and anchor-based approaches to determine minimally important differences: the FACIT experience.

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