C3 and anemia: Patients with lower serum C1q levels (<40.97 μg/ml) showed significantly higher levels of SLEDAI (P < 0.001), significantly lower levels of C3 (P < 0.001), and significantly higher incidence of anti-ds-DNA antibody (P = 0.003), hematuria (P = 0.021), and anemia (P = 0.004; Table 2).