Criteria for defining and dating onset of organ system involvement in systemic sclerosis.

Objectives: This study was undertaken to develop standardized definitions of individual organ system involvement in systemic sclerosis and their date of onset, with the overall goal of increasing the internal validity and comparability of future clinical trials and observational studies. Methods: Under the auspices of the Scleroderma Clinical Trials Consortium, an international working group of experts and patient partners formed nine sub-groups for each of the following organ systems: skin, peripheral vascular, joints/tendons, skeletal muscle, gastrointestinal tract, parenchymal lung, pulmonary arterial hypertension, heart, and kidney. Lists of elements that could be considered as potential criteria for involvement of each organ system were compiled. A three-round Delphi exercise was conducted among Scleroderma Clinical Trials Consortium and the European Scleroderma Trials and Research group members in order to achieve consensus with the larger systemic sclerosis community. Informed by the results of the Delphi exercise, sub-groups proposed composite criteria for organ system involvement, and the international working group approved the final criteria. Results: This consensus-driven project involved over 160 systemic sclerosis experts from around the world, organ system specialists, and patient participants. We developed criteria for nine individual organ systems commonly involved in systemic sclerosis, made recommendations for the date of onset thereof, and provided explanatory notes. Conclusions: We believe these standardized criteria for systemic sclerosis organ system involvement and date of onset provide useful guidelines for investigators and will enhance the comparability of future clinical trials and observational studies in this disease.