Erythropoiesis-stimulating agent slows the progression of chronic kidney disease: a possibility of a direct action of erythropoietin

Background Controversy exists regarding the renoprotective effect of erythropoiesis-stimulating agent (ESA) in progressive chronic kidney disease (CKD) with renal anemia. In this study, we examined whether ESA therapy has a renoprotective effect in progressive CKD. Methods The subjects in this retrospective observational study were 68 non-dialysis dependent CKD patients with renal anemia. We compared the progression rate (PR), defined by the slope of the linear regression line of estimated glomerular filtration rate, measured during 6 months just before and after the start of ESA therapy. We also investigated the factors affecting renoprotective efficacy of ESA therapy against the progression of CKD. Results Median (interquartile range) PR decreased significantly from 6.2 (3.7-12.7) to 4.0 (-0.3 to 7.3) mL/min/1.73 m(2)/year after the start of ESA therapy. Blood pressure levels and rate of medication with renin-angiotensin system inhibitors were comparable between the two periods. Next, we investigated the factors affecting renoprotective efficacy of ESA therapy against the progression of CKD. Thirty patients were good renal responders, defined as those with the ratio of post-/pre-PR of<0.5 and the difference of pre- minus post-PR>5.0mL/min/1.73 m(2)/year, and 38 patients were poor renal responders who did not meet the definition of good renal responders. Multivariable logistic regression analysis showed that weekly ESA dose, but not increase in hemoglobin level, was a significant and independent determinant of the renoprotective effect of ESA. Conclusion ESA therapy slows the progression of CKD and part of the effect might be attributed to the direct renoprotective action of ESA.