Immunosuppressive treatment in diffuse cutaneous systemic sclerosis is associated with an improved composite response index (CRISS)

BACKGROUND: Outcomes of therapeutic studies in diffuse cutaneous systemic sclerosis (dcSSc) have mainly been measured for specific organs, particularly the skin and lungs. A new composite response index in dcSSc (CRISS) has been developed for clinical trials. The goal of this study was to determine whether, in an observational dcSSc cohort, immunosuppression was associated with global disease improvement measured with the CRISS. METHODS: We conducted a retrospective cohort study in a multi-centered SSc registry comparing 47 patients newly exposed to immunosuppression for ≥ 1 year to 254 unexposed patients. Inverse probability of treatment weighting (IPTW) was performed to create comparable exposed and unexposed groups by balancing for age, sex, disease duration, modified Rodnan skin score (mRSS), forced vital capacity, patient and physician global assessments, and Health Assessment Questionnaire score. A CRISS score ≥ 0.6 at 1 year was defined as improvement. RESULTS: Exposed patients had shorter disease duration (5.5 versus 11.7 years, p < 0.01), more interstitial lung disease (67.4% versus 40.3%, p < 0.01), and worse physician global severity scores (4.2 versus 2.5 points, p < 0.01) compared to unexposed patients. Improvement in CRISS scores was more common in exposed patients after IPTW (odds ratio 1.85, 95% confidence interval 1.11, 3.09). Of the individual CRISS variables, only mean patient global assessment scores were significantly better among exposed than unexposed patients (− 0.4 versus 0 points, p = 0.03) while other variables including mRSS were similar. CONCLUSION: Using a composite response measure, immunosuppression was associated with better outcomes at 1 year in a dcSSc cohort. These results provide real-world data that align with clinical trials to support our current use of immunosuppression.