Objective: To determine the variability of several clinical outcome measurements commonly used in scleroderma clinical trials.
Methods: Ten researchers, members of a multicenter placebo controlled trial of methotrexate in early diffuse scleroderma, studied the intraobserver and interobserver variability of variables used to assess efficacy in scleroderma trials.
Results: For most measures, the variability within an observer was less than that found between observers, and therefore the intraobserver reliability was better than the interobserver reliability. The reliability of the modified Rodnan skin score exceeded the Rodnan skin score. Measures with inherent interpretation such as global assessments and skin scores had more variability than easily performed measurements such as grip strength and oral opening.
Conclusion: Some of our variability was higher than variability previously reported; this could be due to the large number of examiners and patients in our study.