Immunosuppressive Drugs in Early Limited Cutaneous Systemic Sclerosis May Prevent Global Damage Accrual.

Objective: Organ damage in systemic sclerosis (SSc) in individual organs such as the lungs may be prevented by immunosuppressive drugs (IS). A new measure of global organ damage, the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI), has allowed us to investigate whether IS may reduce global organ damage accrual in early SSc.

Methods: This was a retrospective study of patients with < 2 years disease duration in Canadian and Australian SSc cohorts. Patients with either limited cutaneous (lcSSc) or diffuse cutaneous (dcSSc) SSc were observed separately and divided into ever or never exposed to IS groups. The SCTC-DI was the outcome and inverse probability of treatment weighting (IPTW) was used to balance the study groups and to fit a marginal structural generalized estimating equation (GEE) model.

Results: In the lcSSc cohort, there were 210 subjects of which 34% were exposed to IS at some time. Exposure to IS was associated with lower damage scores. In the dcSSc cohort, there were 192 subjects of which 76% were exposed to IS at some time. Exposure to IS was not associated with damage scores.

Conclusion: In this retrospective observational cohort study, using IPTW to adjust for confounders, we found a protective effect of the use of IS on damage accrual in lcSSc. We were unable to determine such an effect in dcSSc but unknown confounders may have been present and prospective studies of IS in dcSSc should include the SCTC-DI to determine the possible effect of IS on damage accrual.