In the total population, three anemia biomarkers (Hb, Hct, and RDW) individually mediated the association between eGFR and all-cause mortality (Table 3), and the estimated univariable mediating effects of Hb, Hct, and RDW were 14.48 (95% CI 8.62–21.07%), 15.14 (9.22–21.07%) and 36.48 (29.96–43.01%), respectively. Here, GSTM1 is linked to anemia (phenotype).