Background/Purpose: Randomized clinical trials (RCTs) of treatment of diffuse systemic sclerosis (dcSSc) would benefit from a composite index that predicted efficacy better than current standard measures that are based on single organ systems.  As a first step to achieve the goal of a validated composite index, a longitudinal observational registry was launched in the U.S.: the combined response index for SSc (CRISS) cohort.  We aim to compare the baseline characteristics of the 200 patient CRISS cohort with those of 3 large dSSc clinical trials to ascertain whether the CRISS patients are representative of the patients in dSSc clinical trials.

Methods: We compared the baseline clinical characteristics of the 200 patients enrolled in the CRISS cohort to patients who participated in 3 large RCTs in dcSSc: the Oral Collagen, the D-Penicillamine, and the Relaxin trials.  Patients were enrolled into the CRISS cohort from 4 scleroderma centers and all study patients have early dcSSc (< 5 years from first non-Raynaud's sign or symptom).  

Results: The Table provides comparison between CRISS and the 3 RCTs. The CRISS cohort is similar across all 3 trials for most of the 15 selected measures. The CRISS cohort is similar to the Oral Collagen trial being statistically not different for 13 of 15 measures; it is similar to the D-Pen cohort for 11 of 15 measures and similar to the Relaxin cohort for 9 of 15 measures. While statistical differences existed for age, gender, BMI, tender joints, DLCO and MD global in some comparisons, majority were not clinically meaningful.

Conclusion: The CRISS cohort is generally representative of patients enrolled in large multicenter RCTs of dcSSc and will be fit for the purpose of developing a composite response index.  The CRISS cohort will also be a valuable resource for studying the clinical characteristics of patients with early dsSSc followed at major academic centers and treated according to the current standards of care.