Maintaining higher Hb levels (11.0 ≤ Hb < 13.0 g/dL) with darbepoetin alfa has been shown to better preserve the renal function in patients with CKD not on dialysis compared to maintaining lower Hb levels (9.0 ≤ Hb < 11.0 g/dL) [34]. Here, GSTM1 is linked to chronic kidney disease.