In general, without distinction between SSc subtypes, the correlation analysis showed that the PRE value of Work_index correlated positively with the diffusion capacity of the lung for carbon monoxide (DLCO; r = 0.498, p = 0.003) and C-reactive protein (CRP; r = 0.400, p = 0.019), whereas the POST value correlated with the left ventricular ejection fraction (LVEF; r = 0.349, p = 0.034) and mRSS (r = 0.439, p = 0.005; Figure 1A,B). Here, CRP is linked to systemic sclerosis.