Prevalence and related factors of the absence of anemia among Chinese chronic hemodialysis patients: a multicenter cross-sectional study.

BACKGROUND: Some chronic hemodialysis (HD) patients can maintain normal hemoglobin levels without requiring erythropoiesis-stimulating agents (ESAs). However, the prevalence and the factors associated with this condition in Chinese chronic HD patients have not been reported. The aim of this study was to investigate clinical features, iron metabolism, and other characteristics to survey the prevalence rate and the related factors of this condition among Chinese chronic HD patients.

METHODS: A total of 1,318 chronic HD patients participated in this study. The patients were classified into a non-ESA group (n = 11) and an ESA group (n = 1,307). The r-HuEPO-independent (non-ESA) HD patients were defined as having hemoglobin greater than 12 g/dl for more than 6 months without r-HuEPO injection, blood transfusion, or androgen therapy. Epidemiological and laboratory data were collected. Renal sonography was also performed on each patient to evaluate the formation of renal and liver cysts, and the number and size of the cysts were recorded.

RESULTS: Approximately 0.84 % of all HD patients were found to be r-HuEPO independent. The non-ESA group had a higher proportion of men (79.6 vs. 58.3 %), a longer duration of renal replacement therapy (RRT) (8.6 ± 6.1 vs. 5.1 ± 3.3 years), a higher prevalence of adult polycystic kidney disease (APKD) (46.3 vs. 9.7 %), a higher prevalence of hepatitis C virus (HCV) liver disease (26.2 vs. 3.2 %, P < 0.01), and had older patients (63.3 ± 13.6 vs. 49.6 ± 13.5 years). Endogenous erythropoietin levels in the non-ESA group were significantly higher than those in the ESA group (61.8 ± 27.1 vs. 29.3 ± 11.7 mU/ml). Non-ESA patients had a significantly higher number of renal (38.1 vs. 13.2 %) and hepatic cysts (9.3 vs. 1.9 %), which were also larger in size (2.9 ± 1.6 vs. 1.3 ± 0.3 cm) compared with those of patients in the ESA group. No significant difference in iron metabolism was found between two groups. In the multivariate Cox analysis, the independent predictor factors for the absence of anemia in these HD patients were the number of renal cysts >6 cysts (95 % CI 1.058-1.405; P = 0.00), endogenous erythropoietin levels (95 % CI 1.139-1.361; P = 0.05), HCV+ liver disease (95 % CI 1.129-1.316; P = 0.01), and time on RRT (95 % CI 1.019-1.263; P = 0.05).

CONCLUSIONS: To our knowledge, this study is the first to report on r-HuEPO independence among Chinese HD patients. The prevalence among Chinese chronic HD patients is significantly lower than that reported in the literature. Factors contributing to this condition are complex and multiple. The frequency of this condition is higher in men and in older patients with long-term RRT, in patients with HCV+ liver disease, and in APKD patients. This condition is associated with increased endogenous erythropoietin production and the presence of renal and hepatic cysts.