Reliability and Validity of the Tender and Swollen Joint Counts and the Modified Rodnan Skin Score in Early Diffuse Cutaneous Systemic Sclerosis: Analysis from the Prospective Registry of Early Systemic Sclerosis Cohort

Abstract

Objective.To determine the inter/intraobserver reliability of the tender and swollen joint counts (TJC, SJC) and the modified Rodnan Skin Score (mRSS) in diffuse cutaneous systemic sclerosis (dcSSc) and to assess content validity of the TJC/SJC.Methods.Ten rheumatologists completed the SJC, TJC, and mRSS on 7 patients. Musculoskeletal ultrasound (MSUS) was performed.Results.Interobserver and intraobserver reliability for the TJC was 0.97 and 0.99, for the SJC was 0.24 and 0.71, and for the mRSS was 0.81 and 0.94, respectively. MSUS abnormalities did not correspond with SJC/TJC.Conclusion.We demonstrate excellent inter- and intraobserver reliability for the mRSS and TJC in dcSSc. However, the SJC and TJC did not correspond to MSUS.