Improvement in skin thickening in systemic sclerosis associated with improved survival

The natural history of changes in skin thickening in diffuse scleroderma is quite variable, but the significance of these changes is not clear. Clinical trials are using changes in skin thickening as the primary outcome measure, and thus it would be helpful to determine the significance of improvement in skin thickening. The purpose of the present study was to determine whether improvement in skin thickening over time was associated with improved survival.

Patients with early (<3 years) diffuse scleroderma who had a baseline evaluation and a repeat skin assessment (modified Rodnan skin score) performed 2 years later (i.e., they had to live for 2 years) were identified from the prospective, observational Pittsburgh Scleroderma Databank. The percentage of improvement and rate of change in the skin score during that time were determined. Patients with an improvement in their skin thickening of >25% of their peak skin score and a rate of change of at least 5 units/year were defined as the improved group; patients with increased skin thickening or no improvement were termed the no improvement group. Demographic and clinical features, organ system involvement, and survival rates were determined and the groups were compared. Regression and Cox regression analyses were used to determine what features were associated with improved skin thickness and survival.

Two hundred seventy-eight patients fulfilled the entry criteria, 63% in the improved group and 36% in the no improvement group. The groups were similar in terms of clinical and demographic characteristics at the initial visit. The improved group had an average improvement of 50% of their peak skin score at 2 years after the initial visit. Survival was significantly better in the improved group compared with the unimproved group at 5 and 10 years, with rates of 90% and 80%, respectively, in the improved group and 77% and 60%, respectively, in the no improvement group (P < 0.0001). There were no significant differences in the occurrence of severe organ involvement during the first 2 years to account for the later differences in survival. The duration of the use of D-penicillamine was significantly associated with improved skin thickness and improved survival.

Among patients surviving the first few years of diffuse scleroderma, striking improvement in skin thickening may occur in up to two-thirds. This improvement in skin thickening is associated with improved survival. Improvement in skin thickening may be useful as a surrogate for improvement in survival in clinical trials.