Prevalence and associations of anemia of CKD: Kidney Early Evaluation Program (KEEP) and National Health and Nutrition Examination Survey (NHANES) 1999-2004

Background: Early identification of anemia of chronic kidney disease may be important for the development of preventive strategies. We compared anemia prevalence and characteristics in the National Kidney Foundation Kidney Early Evaluation Program (KEEP) and National Health and Nutrition Examination Survey (NHANES) 1999-2004 populations. Methods: Clinical, demographic, and laboratory data were collected from August 2000 to December 31, 2006, from participants in KEEP, a community-based health-screening program targeting individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Anemia was defined as hemoglobin level less than 13.5 g/dL for men and less than 12.0 g/dL for women (Kidney Disease Outcomes Quality Initiative [KDOQI] 2006) or less than 13.0 g/dL for men and less than 12.0 g/dL for women (World Health Organization [WHO]). Results: In KEEP (n = 70,069), 68.3% of participants, and in NHANES (n = 17,061), 52% of participants, were women. African Americans represented 33.9% of the KEEP and 11.2% of the NHANES cohorts, and Hispanics comprised 12.4% of KEEP and 13.2% of NHANES. Using the KDOQ1 classification, anemia was present in 13.9% and 6.3% of KEEP and NHANES participants, whereas using the WHO classification, anemia was present in 11.8% and 5.3%, respectively. In adjusted analysis of KEEP data, KDOQI-defined anemia was significantly more likely in men (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.23 to 1.37); this pattern was reversed when using WHO-defined anemia (OR, 0.68; 95% Cl, 0.64 to 0.72). Adjusted odds of anemia were greater for African American than white KEEP participants (OR, 2.98; 95% Cl, 2.80 to 3.16; OR, 3.00; 95% Cl, 2.81 to 3.20 for KDOQI- and WHO-defined anemia, respectively). Conclusion: Anemia was twice as common in the targeted KEEP chronic kidney disease screening program cohort than in the NHANES sample population. African Americans had a 3-fold increased likelihood of anemia compared with whites. Targeted screening can identify anemia in a high-risk population.