A previous analysis from this cohort found that for every unit decrease in admission serum Hb, the likelihood of CI-AKI increased by 6.5% (Moitinho et al., 2022), as well as a study from the USA that demonstrated that for every 3% reduction in baseline hematocrit, the chances of developing the CI-AKI outcome increased (Nikolsky et al., 2005). This evidence concerns the gene GSTM1 and acute kidney injury.