A disease severity scale for systemic sclerosis: Development and testing

Objective. To develop and test a severity scale for individual organ involv ements in systemic sclerosis (SSc, scleroderma). Methods. An international study group completed the following tasks: (1) de veloped a glossary of terms including all pertinent variables for 9 potenti ally affected organ systems; (2) collected prospective data to determine th e feasibility and practicality of each proposed variable: (3) revised the i nitial list of variables; (1) determined the association of each variable w ith mortality (a proxy for morbidity) using 579 patients in an existing com prehensive longitudinal scleroderma databank; (5) developed a severity grad ing scale for each organ system by discussion and consensus; and (6) extern ally validated the scale using an independent group of 680 patients from th e same databank. Results. Nine organ-specific severity scales were developed from 0 (no docu mented involvement) to 4 (endstage disease). The data required for scale co mpletion are relatively easy and practical for all physicians to obtain. Conclusion. This preliminary severity scale will be useful for assessing di sease 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 a ctivity index.