Myopathy is a Risk Factor for Poor Prognosis of Patients with Systemic Sclerosis: A retrospective cohort study

To compare clinical characteristics and identify long-term outcomes of Chinese patients with systemic sclerosis (SSc) with and without muscle involvement.We retrospectively investigated the medical records, laboratory results, and computed tomography images of 204 consecutive SSc patients. Kaplan-Meier analysis was performed to determine survival rates. Patients were allocated into groups with and without myopathy.The prevalence of myopathy was 21.6%. The myopathy group was more likely to develop diffuse cutaneous involvement (90.9% vs 56%, P = .006), interstitial lung disease (90% vs 56%, P < .001), digestive system involvement (56.7% vs 29.3%, P = .001), pulmonary hypertension (29.5% vs 10.5%, P = .004), and pericardial effusion (25% vs. 10%, P = .019). Patients with myopathy had lower single-breath diffusing capacity of the lung for carbon oxide (46.5 ± 11.1 vs 57.1 ± 13.4, P < .001).Further, the myopathy group has similar results in interstitial lung disease associated higher resolution computed tomography score (186.8 ± 64.5 vs 152.3 ± 45.5, P = .037), Valentini score for disease activity (3.4 ± 0.9 vs 2.0 ± 0.9, P < .001) and modified Rodnan total skin score (19.4 ± 6.1 vs 15.1 ± 7.7, P = .002), compared with non-myopathy group. Kaplan-Meier survival analysis revealed decreased overall survival rate of the myopathy group (P = .028).SSc Patients with myopathy had more severe clinical manifestations and higher disease activity compared with those without, which affected survival rates and indicated worse prognosis.