GDF15 and cardiovascular disorder: Second, because limited number of SLE patients had cardiovascular diseases, or metabolic syndrome, or antiphospholipid syndrome, therefore, we cannot discuss whether there is difference of serum levels of GDF-15 between SLE patients with cardiovascular diseases and patients without cardiovascular diseases, patients with metabolic syndrome and patients without metabolic syndrome, and patients with antiphospholipid syndrome and patients without antiphospholipid syndrome, respectively.