C4A and systemic lupus erythematosus: In addition, serum SOD level and C4 were significantly reduced (P < .05), RDW‐SD, RDW‐CV, and anti‐dsDNA were higher than those of the control group (P < .05), and the clinical characteristics and laboratory examination results of 222 patients with SLE and 202 healthy people are shown in Table 1.