Sensitivity to change of joint count composite indices in 72 patients with systemic sclerosis

Abstract

Objectives: We validated the responsiveness of joint count composite indices (JCCIs) in 72 patients with systemic sclerosis (SSc).

Methods: Changes in Disease Activity Score of 28 Joints using ESR and CRP (DAS28-ESR, DAS28-CRP), Simplified Disease Activity Index (SDAI) and the Clinical Disease Activity Index (CDAI) were evaluated in a one-year follow-up study. Charts of patients including swollen/tender joint counts, laboratory signs of inflammation, and visual analogue scales referring to disease activity, severity and pain were also blindly categorized by two rheumatologists as improved, unchanged or deteriorated. These categories were used as references for the determination of effect size (ES) and standardised response mean (SRM).

Results: Articular inflammation improved in 15, deteriorated in 12, and remained unchanged in 45 (63%) patients with SSc based on the concordant opinion of two clinical investigators. All four JCCIs were sensitive to changes (ES>1; SRM>1). The correlation between changes in JCCIs and the physicians' evaluation was high (r >0.68; p<0.001). Arthritis was predominantly prone to change in patients with high JCCIs, impaired functional status, anti-RNA polymerase III antibodies and patients on DMARD therapy. Synovitis was more prevalent in patients with early diffuse SSc, and tended to improve during the follow-up.

Conclusions: All four JCCIs were sensitive to changes, if tender/swollen joints were present at baseline. Articular inflammation was most prone to change in patients with high JCCIs, impaired functional status and already decreased health-related quality of life at baseline.