Impact of Myositis in Scleroderma Patients Save

Systemic sclerosis (SSc) may have overlap features such as myositis. When present, myositis in SSc is associated with an increased risk of cardiac involvement and a shift in mortality away from ILD towards a greater cardiac risk.

SSc already has a very high disease-specific mortality risk, lead by cardiac causes and interstitial lung disease (ILD).  This report looks at the influence of myositis in SSc patients.

A total of 880 SSc patients from a single center were propensity score matched  for this retrospective analysis. SSc myositis required proximal weakness and elevated muscle enzymes. 

Overall, only 10% (92) SSc patients had myositis. 92 pairs (n = 184) were analysed.  Key takeaways:

• SSc + Myositis group had an increased risk of cardiac involvement (aOR=19.99, 95%CI 2.19–182.26, p = 0.008).
• Higher mRSS also predicted cardiac involvement
• Anti-Scl70 was less common in myositis (25.0% vs. 50.0%, p = 0.009).
• Mortality did not differ (13.0% vs. 9.8%, p = 0.620). 

While non-myositis deaths were more related to ILD caused (33.3%); myositis deaths had greater odds of cardiac failure (25%) with no ILD-related deaths.

Cardiac involvement was significantly associated with mortality (aHR=8.09 (1.36-48.26), p = 0.022), independent of myositis.

 Systematic cardiac surveillance is needed in SSc, especially those presenting with myositis (weakness and elevated CK).