Anemia and end-stage renal disease in patients with type 2 diabetes and nephropathy

Background. Diabetic nephropathy is the leading cause of end-stage renal disease (ESRD). Anemia is common in diabetics with nephropathy; however, the impact of anemia on progression to ESRD has not been carefully examined. Methods. We studied the relationship between baseline hemoglobin concentration (Hb) and progression of diabetic nephropathy to ESRD in 1513 participants enrolled in Reduction in Endpoints in NIDDM with the Angiotensin II Antagonist Losartan study and followed for an average of 3.4 years. Multivariate Cox proportional hazards models were used to analyze the relationship between Hb and ESRD, after adjusting for predictors for ESRD. Analyses were performed with Hb stratified by quartile: first quartile <11.3 g/dL, second quartile 11.3 to 12.5 g/dL, third quartile 12.6 to 13.8 g/dL, and fourth quartile greater than or equal to13.8 g/dL (reference) and as a continuous variable. Results. Baseline hemoglobin concentration was correlated with subsequent development of ESRD. After adjustment for predictors of ESRD, the hazard ratios for the first, second, and third Hb quartiles were 1.99 (95% CI, 1.34-2.95), 1.61 (95% CI 1.08-2.41), and 1.87 (95% CI 1.25-2.80). With hemoglobin as a continuous variable, the adjusted hazard ratio was 0.90 (95% CI 0.84-0.96, P= 0.0013). The average increase in adjusted relative risk was 11% for each 1 g/dL decrease in hemoglobin concentration. Conclusion. Our data suggest that even mild anemia, Hb <13.8 g/dL increases risk for progression to ESRD. Hemoglobin is an independent risk factor for progression of nephropathy to ESRD in type 2 diabetes.