C3 and systemic lupus erythematosus: In terms of variables of interest in patients with SLE, patients with SLD had a lower frequency of hydroxychloroquine use (65% vs 84%, p = 0.04), and higher C3 levels [123 mg/dl (IQR 102–136) vs 99 mg/dl (IQR 78–121), p = 0.004].