SIRT1 and pulmonary arterial hypertension: No significant difference in SIRT1 levels was detected between SSc patients with PAH (median 0.97 ng/mL, IQR 0.49–1.87 ng/mL) and those without PAH (median 0.93 ng/mL, IQR 0.52–1.58 ng/mL; p > 0.05).