Patient acceptable symptom state and minimal clinically important difference for patient-reported outcomes in systemic sclerosis: A secondary analysis of a randomized controlled trial comparing personalized physical therapy to usual care.

BACKGROUND: To estimate patient acceptable symptom state (PASS) and minimal clinically important difference (MCID) for patient-reported outcomes in systemic sclerosis (SSc).

METHODS: We conducted a secondary analysis of the SCLEREDUC trial, a 12-month randomized controlled trial comparing the efficacy of physical therapy to usual care in 220 SSc patients followed-up from September 2005 to October 2010. Self-rated state and change in patient health at 12 months were assessed by using 2 external anchors extracted from the Medical Outcomes Study 36-Item Short-Form. Patients who self-rated their health as "excellent", "very good" or "good" were the PASS group and those who self-rated their health change as "somewhat better" were the MCID group. Main outcomes were the estimates of PASS by using the 75th percentile method and of MCID by using the mean change in scores method for pain and activity limitation.

RESULTS: PASS (95% confidence interval) and mean (SD) MCID estimates at 12 months were 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 (HAQ, range 0-3), 1.27 (1.07 to 1.62) and -0.13 (0.45) for the scleroderma HAQ (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), respectively.

CONCLUSIONS: We provide, for the first time, the PASS and MCID estimates for pain and activity limitation in SSc.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00318188. First Posted: April 26, 2006.