International consensus on a proposed score system for muscle biopsy evaluation in patients with juvenile dermatomyositis: A tool for potential use in clinical trials
Version of Record online: 28 SEP 2007
Copyright © 2007 by the American College of Rheumatology
Arthritis Care & Research
Volume 57, Issue 7, pages 1192–1201, 15 October 2007
How to Cite
Wedderburn, L. R., Varsani, H., Li, C. K. C., Newton, K. R., Amato, A. A., Banwell, B., Bove, K. E., Corse, A. M., Emslie-Smith, A., Harding, B., Hoogendijk, J., Lundberg, I. E., Marie, S., Minetti, C., Nennesmo, I., Rushing, E. J., Sewry, C., Charman, S. C., Pilkington, C. A. and Holton, J. L. (2007), International consensus on a proposed score system for muscle biopsy evaluation in patients with juvenile dermatomyositis: A tool for potential use in clinical trials. Arthritis & Rheumatism, 57: 1192–1201. doi: 10.1002/art.23012
- Issue online: 28 SEP 2007
- Version of Record online: 28 SEP 2007
- Manuscript Accepted: 8 MAR 2007
- Manuscript Received: 9 AUG 2006
- Myositis Support Group, UK
- Cathal Hayes Research Foundation
- Arthritis Research Campaign Fellowship
- Muscle biology;
- Pediatric rheumatology;
- Juvenile dermatomyositis;
To devise and test a system with which to evaluate abnormalities on muscle biopsy samples obtained from children diagnosed with juvenile dermatomyositis (DM).
We established an International Consensus Group on Juvenile DM Biopsy and carried out 2 phases of consensus process and scoring workshops. Biopsy sections (n = 33) were stained by standard methods. The scoring tool was based on 4 domains of change: inflammatory, vascular, muscle fiber, and connective tissue. Using a Latin square design, biopsy samples were scored by 11 experts for items in each domain, and for a global abnormality measure using a 10-cm visual analog score (VAS 0–10). The tool's reliability was assessed using an intraclass correlation coefficient (ICC) and scorer agreement (α) by determining variation in scorers' ratings.
There was good agreement in many items of the tool, and several items refined between the meetings improved in reliability and/or agreement. The inflammatory and muscle fiber domains had the highest reliability and agreement. The overall VAS score for abnormality had high agreement and reliability, reaching an ICC of 0.863 at the second consensus meeting.
We propose a provisional scoring system to measure abnormalities on muscle biopsy samples obtained from children with juvenile DM. This system needs to be validated, and then could be used in prospective studies to test which features of muscle pathology are prognostic of disease course or outcome. We suggest that the process we used could be a template for developing similar systems in other forms of myositis.