Patient Acceptable Symptom State and Minimally Clinically Important Difference for Patient-Reported Outcomes in Systemic Sclerosis: A Secondary Analysis of the Sclereduc Trial

We aimed to determine patient acceptable symptom state (PASS) and minimally clinically important improvement (MCII) estimates for patient-reported outcomes (PROs) in systemic sclerosis (SSc). Two hundred and twenty patients participated in the SCLEREDUC trial, a 12-month, randomised controlled study comparing the efficacy on disability assessed by the HAQ-DI at 12-months of physical therapy compared to usual care in patients with SSc. Self-rated state and change in patient health at 12 months post-randomization were assessed by using 2 external anchoring questions from the Medical Outcomes Study 36-Item Short Form. Patients who self-rated their health as "excellent", "very good" or "good" were considered as having an acceptable symptom state and those who self-rated their health change at 12 months as "somewhat better" were considered as minimally improved. PASS estimates were obtained using the 75th percentile method and the MCII estimates by using the mean change in scores method. Answers to both anchoring questions at 12 months were available for 151/220 (68.6%) participants. PASS (95% CI) and mean (SD) MCII estimates at 12 months were respectively: 53.75 (34.00 to 68.00) and −6.74 (32.02) for the joint-pain visual analog scale (range 0–100), 1.41 (1.13 to 1.63) and −0.21 (0.48) for the Health Assessment Questionnaire Disability Index (HAQ-DI, range 0–3), 1.27 (1.07 to 1.62) and −0.13 (0.45) for the scleroderma HAQ (sHAQ, range 0–3), 26.00 (17.00 to 37.00) and −3.38 (9.87) for the Cochin Hand Function Scale (range 0–90), and 19.40 (17.20 to 21.90) and −5.69 (6.79) for the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire (range 0–30). For all PROs, higher scores indicate higher symptoms levels. The present study provides PASS and MCII estimates for commonly used PROs in SSc. These estimates are useful in interpreting the clinical relevance of outcomes used in patients' care and in clinical trials. ClinicalTrials.gov identifier: NCT00318188.