FGF21 and non-alcoholic fatty liver: Subgroup comparisons according to the disease severity in studies with histological confirmation showed: (i) no statistical difference in circulating FGF-21 between patients with NAFL and controls (n = 9; SMD: 0.22; 95% CI: −0.49, 0.93; p = 0.540; Table 3; Fig. S2a-b); (iii) higher FGF-21 levels in patients with NASH compared to controls (n = 12; SMD: 1.30; 95% CI: 0.35, 2.24; P = 0.007; Table 3; Fig. S2c-d); no statistical difference in circulating FGF-21 between patients with NAFL and patients with NASH (n = 9; SMD: 1.17; 95% CI: −0.06, 2.39; p = 0.060; Table 3; Fig. S2e-f).