About the Soluble Biomarkers Working Group The OMERACT Soluble Biomarkers Working Group is Jasvinder A SinghCo-Chair Vibeke StrandCo-Chair Peter TugwellCo-Chair Working Group Publications Expand Definitions and Validation Criteria for Biomarkers and Surrogate Endpoints: Development and Testing of a Quantitative Hierarchical Levels of Evidence Schema Testing of the Preliminary OMERACT Validation Criteria for a Biomarker to Be Regarded as Reflecting Structural Damage Endpoints in RA Clinical Trials: The Example of CRP Development of Draft Validation Criteria for a Soluble Biomarker to Be Regarded as a Valid Biomarker Reflecting Structural Damage Endpoints in RA and SpA Clinical Trials Testing of the OMERACT 8 Draft Validation Criteria for a Soluble Biomarker Reflecting Structural Damage in RA: A Systematic Literature Search on 5 Candidate Biomarkers Reappraisal of OMERACT 8 Draft Validation Criteria for a Soluble Biomarker Reflecting Structural Damage Endpoints in RA, PsA, and Spondyloarthritis: The OMERACT 9 v2 Criteria Proposal for Levels of Evidence Schema for Validation of a Soluble Biomarker Reflecting Damage Endpoints in RA, PsA, and AS, and Recommendations for Study Design