IL17A and systemic lupus erythematosus: Figure 2 revealed that 22 studies reported the correlation (r) between the disease activity and circulating IL-17 level in patients with SLE (Nakhjavani et al. [39] provided two separate r between IL-17 level and disease activity in SLE patients with/without lupus nephritis), and the pooled Fisher z value was 0.40 (95% CI: 0.25-0.55; I2 = 83.8%, P < 0.001).