Rheumatology Advance Access originally published online on July 14, 2009
Rheumatology 2009 48(9):1143-1146; doi:10.1093/rheumatology/kep202
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Sensitivity to change of the modified Rodnan skin score in diffuse systemic sclerosis—assessment of individual body sites in two large randomized controlled trials
1UCLA-Olive View, Sylmar, 2Department of Medicine, Division of Rheumatology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 3Department of Medicine, University of Michigan, Ann Arbor, MI and 4Department of Medicine, University of Tennessee, Memphis, TN, USA.
Correspondence to: Dinesh Khanna, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, 1000 Veteran Avenue, Rm 32–59 Rehabilitation Building, Los Angele, CA 90095, USA. E-mail: dkhanna{at}mednet.ucla.edu
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Abstract |
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Objective. The modified Rodnan skin score (MRSS) is a standard outcome measure for skin disease in SSc and calculated by summation of skin thickness in 17 different body sites (total score = 51). Our objective was to evaluate the sensitivity of change over time of individual body sites used in the calculation of total MRSS.
Methods. We analysed two randomized placebo controlled clinical trials investigating the effect of either recombinant human relaxin or type I oral collagen in dcSSc. Both trials used MRSS as the primary outcome measure. We used a change of >10 mm (on a 0–100 VAS) in the patient global assessment (PGA) as the clinically important improvement. We calculated the mean change and the effect size (ES) for each individual body site used in the total MRSS for each study. Magnitude of ES was assessed using Cohen's rule of thumb for ES.
Results. In the relaxin and collagen studies, 71 of 199 patients (36%) and 54 of 129 (42%) of patients had an improvement >10 mm on the PGA at 6 and 12 months, respectively. Total MRSS had large ES in both studies (0.85–0.98); the chest, forearms and hands had moderate ES (0.50–0.74); and the lower extremities, face, abdomen and fingers had small ES (0.16–0.49).
Conclusion. Certain body sites (hands, forearms and chest) are more sensitive to change compared with other body sites in two randomized clinical trials. It remains to be seen whether decreasing the number of body sites by exclusion of relatively static areas would further increase the sensitivity to change over time of the total MRSS.
KEY WORDS: Modified Rodnan skin score, Clinical trials, Scleroderma, Outcome measures
Submitted 14 April 2009; Accepted 9 June 2009