ACE and chronic kidney disease: In CKD, concomitant use of iron preparations (OR = 0.3, 95% CI: 0.2–0.7; P-value = 0.002) and of high dosage of angiotensin-converting enzyme inhibitors/angiotensin II-receptor blockers (OR = 0.5, 95% CI: 0.3–0.9; P-value = 0.022) were protective factors against ESA hyporesponsiveness.