Damage Trajectories in Systemic Sclerosis Using Group‐Based Trajectory Modeling

OBJECTIVE: Systemic sclerosis (SSc) is an autoimmune disease characterized by progressive organ damage, which can be measured using the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI). We aimed to identify whether distinct trajectories of damage accrual exist and to determine which variables are associated with different trajectory groups. METHODS: Incident cases of SSc (<2 years) were identified in the Australian Scleroderma Interest Group and Canadian Scleroderma Research Group prospective registries. Group-based trajectory modeling was used to identify SCTC-DI trajectories over the cohort's first 5 annual visits. Baseline variables associated with trajectory membership in a univariate analysis were examined in multivariable models. RESULTS: A total of 410 patients were included. Three trajectory groups were identified: low (54.6%), medium (36.2%), and high (10.3%) damage. Patients with faster damage accrual had higher baseline SCTC-DI scores. Older age (odds ratio [OR] 1.57 [95% confidence interval (95% CI) 1.18-2.10]), male sex (OR 2.55 [95% CI 1.10-5.88]), diffuse disease (OR 6.7 [95% CI 2.57-17.48]), tendon friction rubs (OR 5.4 [95% CI 1.86-15.66]), and elevated C-reactive protein level (OR 1.98 [95% CI 1.49-2.63]) increased the odds of being in the high-damage group versus the reference (low damage), whereas White ethnicity (OR 0.31 [95% CI 0.12-0.75]) and anticentromere antibodies (OR 0.24 [95% CI 0.07-0.77]) decreased the odds. CONCLUSION: We identified 3 trajectories of damage accrual in a combined incident SSc cohort. Several characteristics increased the odds of belonging to worse trajectories. These findings may be helpful in recognizing patients in whom early aggressive treatment is necessary.