A disease severity scale for systemic sclerosis: development and testing.

Objective: To develop and test a severity scale for individual organ involvements in systemic sclerosis (SSc, scleroderma).

Methods: An international study group completed the following tasks: (1) developed a glossary of terms including all pertinent variables for 9 potentially affected organ systems; (2) collected prospective data to determine the feasibility and practicality of each proposed variable; (3) revised the initial list of variables; (4) determined the association of each variable with mortality (a proxy for morbidity) using 579 patients in an existing comprehensive longitudinal scleroderma databank; (5) developed a severity grading scale for each organ system by discussion and consensus; and (6) externally validated the scale using an independent group of 680 patients from the same databank.

Results: Nine organ-specific severity scales were developed from 0 (no documented involvement) to 4 (endstage disease). The data required for scale completion are relatively easy and practical for all physicians to obtain.

Conclusion: This preliminary severity scale will be useful for assessing disease severity status in individual patients both at one point in time and longitudinally. The severity scale will assist in the design and conduct of clinical trials and the comparison of study populations with one another. The scale will serve as a framework for developing a scleroderma disease activity index.