Evaluation of the Reliability of the Challenge when used to Measure Advanced Motor Skills of Children with Cerebral Palsy

ABSTRACT

Aims: The Challenge was designed as an extension to the GMFM-66 to assess advanced motor skills of children with cerebral palsy (CP) who walk/run independently. This study evaluated the Challenge's inter-rater and test–retest reliability. Methods: Thirty children with CP (GMFCS level I [n = 24] and II [n = 6]) completed the Challenge, with re-testing one to two weeks later. Seven physiotherapist assessors passed the Challenge criterion test pre-administration. A single assessor administered and scored test and retest sessions (test–retest reliability). A second assessor independently scored one of these sessions (inter-rater reliability). Results: Inter-rater reliability was excellent (ICC = 0.97, 95%CI 0.94–0.99, CoV < 10%), with no bias (Bland-Altman plot). Test–retest ICC was excellent (ICC = 0.94, 95% CI 0.88–0.97. CoV < 10%, and Minimum Detectable Change (MDC₉₀) was 4.47 points. Many participants indicated practising at home pre-retest session. Conclusions: There was strong rating consistency between assessors. While test–retest ICC estimates were also high, Challenge scores were higher at retest. The MDC₉₀ was still in a range (>4.5 points) that seems clinically viable for change detection. Test–retest reliability could be reassessed with children instructed not to practice between assessments to determine the extent to which between-session practice influenced scores.

KEYWORDS:

• Cerebral palsy
• advanced motor skills
• test-retest reliability
• outcome measurement

Acknowledgments

The authors thank the children who gave their time and personal insights during the Challenge testing as well as our PT assessor team for the reliability study component: Puja Ahluwalia, Mary Huggins, Adriana Kubon, Susan Bowman, Kim Pollard, Janet Mannen and Deana Mercier. We also thank Gloria Lee (Research Co-ordinator) and Emily Brewer (Research Assistant) for their assistance.

Declaration of Interest

The first author was involved in the creation of the Challenge but does not receive any personal remuneration from its use. The study was funded by the Canadian Institutes of Health Research (CIHR) within the context of a larger Rasch scaling grant. The authors alone are responsible for the content and writing of this article.

Funding Information

The study was funded by the Canadian Institutes of Health Research (MOP 119367) within the context of a larger Rasch scaling grant.

About the Authors

F. Virginia Wright, PhD, PT is Senior Scientist, Bloorview Research Institute, Toronto, Canada and Professor (status), Department of Physical Therapy, University of Toronto. She holds the Holland Bloorview Childrens Hospital Foundation Chair in Pediatric Rehabilitation.

Chun Ying Lam, BSc, began her work on the Challenge as a Ward Family Summer Student Research Program trainee at Bloorview Research Institute and continued with it during her subsequent role as a Research Assistant at Holland Bloorview Kids Rehabilitation Hospital.

Bhavnita Mistry, MA, is a Research Coordinator at the Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital.

Joan Walker was a Research Assistant with the Challenge project in the Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital.