SIRT1 and interstitial lung disease: Since, when comparing SSc subgroup medians, we found significant differences in serum levels of both SIRT1 and SIRT3 according to the cutaneous subset, the presence of ILD, and the severity of the NVC pattern, we finally carried out multiple logistic regression analysis combining serum SIRT1 and SIRT3 as independent variables, and one of the three abovementioned disease phenotypes as a single dependent variable each time.