Minimally important difference in diffuse systemic sclerosis: results from the d-penicillamine study

• Published in: Annals of the rheumatic diseases Vol. 65; no. 10; pp. 1325 - 1329
• Main Authors: Khanna, D, Furst, D E, Hays, R D, Park, G S, Wong, W K, Seibold, J R, Mayes, M D, White, B, Wigley, F F, Weisman, M, Barr, W, Moreland, L, Medsger, T A, Steen, V D, Martin, R W, Collier, D, Weinstein, A, Lally, E V, Varga, J, Weiner, S R, Andrews, B, Abeles, M, Clements, P J
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and European League Against Rheumatism 01.10.2006; BMJ; Elsevier Limited; BMJ Group
• Subjects: Adult; Antirheumatic Agents - administration & dosage; Antirheumatic Agents - therapeutic use; Biological and medical sciences; Bones, joints and connective tissue. Antiinflammatory agents; Clinical trials; d-Pen; d-penicillamine; Disability Evaluation; Disease; Diseases of the osteoarticular system; Dose-Response Relationship, Drug; Estimates; Extended Report; Female; Follow-Up Studies; HAQ-DI; Health Assessment Questionnaire—Disability Index; Health Status Indicators; health-related quality of life; HRQOL; Humans; Male; Medical sciences; MID; Middle Aged; minimally important difference; modified Rodnan Skin Score; mRSS; Penicillamine - administration & dosage; Penicillamine - therapeutic use; Pharmacology. Drug treatments; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Scleroderma, Diffuse - drug therapy; Scleroderma, Diffuse - rehabilitation; Severity of Illness Index; Skin; SSc; systemic sclerosis; Treatment Outcome; Sulfur containing aminoacid; Diffuse; Immunopathology; Connective tissue disease; Skin disease; Systemic disease; Rheumatology; Chelating agent; Autoimmune disease; Antirheumatic agent; Penicillamine; Scleroderma
• ISSN: 0003-4967; 1468-2060
• DOI: 10.1136/ard.2005.050187

Objective: To estimate minimally important differences (MIDs) in scores for the modified Rodnan Skin Score (mRSS) and Health Assessment Questionnaire—Disability Index (HAQ-DI) in a clinical trial on diffuse systemic sclerosis (SSc). Participants and methods: 134 people participated in a 2-year, double-blind, randomised clinical trial comparing efficacy of low-dose and high-dose d-penicillamine in diffuse SSc. At 6, 12, 18 and 24 months, the investigator was asked to rate the change in the patient’s health since entering the study: markedly worsened, moderately worsened, slightly worsened, unchanged, slightly improved, moderately improved or markedly improved. Patients who were rated as slightly improved were defined as the minimally changed subgroup and compared with patients rated as moderately or markedly improved. Results: The MID estimates for the mRSS improvement ranged from 3.2 to 5.3 (0.40–0.66 effect size) and for the HAQ-DI from 0.10 to 0.14 (0.15–0.21 effect size). Patients who were rated to improve more than slightly were found to improve by 6.9–14.2 (0.86–1.77 effect size) on the mRSS and 0.21–0.55 (0.32–0.83 effect size) on the HAQ-DI score. Conclusion: MID estimates are provided for improvement in the mRSS and HAQ-DI scores, which can help in interpreting clinical trials on patients with SSc and be used for sample size calculation for future clinical trials on diffuse SSc.