Racial variations in erythropoietic response to epoetin alfa in chronic kidney disease and the impact of smoking.

BACKGROUND: Of the known risk factors for chronic kidney disease (CKD), race represents one that is non-modifiable, while smoking is another that is modifiable. Moreover, smoking tends to increase red blood cell mass, which is frequently diminished in CKD. No studies have examined the interplay of race with smoking on anaemia management in patients with CKD. METHODS: We examined the effects of smoking on anaemia management in CKD and its variation across race in a previously conducted study of CKD patients (n = 1312) initiated on weekly epoetin alfa and followed for 16 weeks. Smoking status was classified as current vs non-smoker. Race was classified as African-American vs non-African-American. Changes in estimated glomerular filtration rate, urinary albumin excretion, and erythropoietic response to weekly epoetin alfa were examined. RESULTS: Overall, African-Americans had lower baseline Hb than non-African-Americans. African-American non-smokers did not mount an erythropoetic response comparable to other non-smokers by final Hb (mean 11.29 g/dl vs 11.64 g/dl, P<0.001) or week 16 Hb (mean 11.61 g/dl vs 11.86 g/dl, P = 0.02). However, African-American smokers had a more significant erythropoietic response than their non-smoking counterparts and were comparable to their smoking non-African-American counterparts. There was no effect of smoking on renal function or urinary protein excretion over the course of the study. CONCLUSION: African-American non-smokers exhibit a diminished response to standard epoetin alfa dosing than non-smokers in other races. However, African-American smokers with CKD exhibit a response to epoetin alfa comparable to patients of other races. These findings may have implications for African-Americans who have CKD-related anaemia.