In spite of this, HR values for cumulative mortality were higher for EPO than for anemia (HR 4.05, 95% CI 2.29–7.16, p < 0.001 for logEPO vs. HR 2.40, 95% CI 1.51–3.80, p < 0.001 for hemoglobin). Here, EPO is linked to anemia (phenotype).