International Comparison of the Relationship of Chronic Kidney Disease Prevalence and ESRD Risk Stein I. Hallan,* † Josef Coresh, ‡§ Brad C. Astor, ‡ Arne Åsberg,  Neil R. Powe, ‡§ Solfrid Romundstad, ¶ ** Hans A. Hallan, ¶ Stian Lydersen, † and Jostein Holmen** *Department of Medicine, Division of Nephrology, and  Department of Medical Biochemistry, St. Olav University Hospital, and † Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway; ‡ Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Medical Institutions, and § Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; ¶ Department of Medicine, Levanger Hospital, Levanger, Norway; and **HUNT Research Centre, Faculty of Medicine, Norwegian University of Science and Technology, Verdal, Norway ESRD incidence is much lower in Europe compared with the United States. This study investigated whether this reflects a difference in the prevalence of earlier stages of chronic kidney disease (CKD) or other mechanisms. CKD prevalence in Norway was estimated from the population-based Health Survey of Nord-Trondelag County (HUNT II), which included 65,181 adults in 1995 through 1997 (participation rate 70.4%). Data were analyzed using the same methods as two US National Health and Nutrition Examination Surveys in 1988 through 1994 (n  15,488) and 1999 through 2000 (n  4101). The primary analysis used gender-specific cutoffs in estimating persistent albuminuria for CKD stages 1 and 2. ESRD rates and other relevant data were extracted from national registries. Total CKD prevalence in Norway was 10.2% (SE 0.5): CKD stage 1 (GFR >90 ml/min per 1.73 m 2 and albuminuria), 2.7% (SE 0.3); stage 2 (GFR 60 to 89 ml/min per 1.73 m 2 and albuminuria), 3.2% (SE 0.4); stage 3 (GFR 30 to 59 ml/min per 1.73 m 2 ), 4.2% (SE 0.1); and stage 4 (GFR 15 to 29 ml/min per 1.73 m 2 ), 0.2% (SE 0.01). This closely approximates reported US CKD prevalence (11.0% in 1988 through 1994 and 11.7% in 1999 through 2000). The relative risk for progression from CKD stages 3 or 4 to ESRD in US white patients compared with Norwegian patients was 2.5. This was only modestly modified by adjustment for age, gender, and diabetes. Age and GFR at start of dialysis were similar, hypertension and cardiovascular mortality in the populations were comparable, but US white patients were referred later to a nephrologist and had higher prevalence of obesity and diabetes. In conclusion, CKD prevalence in Norway was similar to that in the United States, suggesting that lower progression to ESRD rather than a smaller pool of individuals at risk accounts for the lower incidence of ESRD in Norway. J Am Soc Nephrol 17: 2275–2284, 2006. doi: 10.1681/ASN.2005121273 T here has been a dramatic rise in the number of patients with ESRD in both Europe and North America during the past decades. There is significant disparity, how- ever, in ESRD incidence rates between the two continents: Incidence rates are three times higher in the United States compared with Norway and Great Britain (1,2). Data on the prevalence of chronic kidney disease (CKD) in Europe are limited, making it unclear whether the higher ESRD incidence in the United States reflects a higher burden of all stages of CKD (3,4). The relationship between the prevalence of earlier stages of CKD and the incidence of ESRD is complex (5–9): US CKD prevalence has been relatively stable in the past decade, whereas ESRD incidence has increased significantly, and US black patients have a three times higher incidence of ESRD despite similar prevalences of CKD. This can be due to differ- ences in other mechanisms, such as more rapid progression or greater initiation of dialysis. Early stages of CKD also result in a higher risk for complications, cardiovascular disease, and mortality, which pose a larger absolute risk than ESRD. Fur- thermore, identifying and treating individuals with early stages of CKD is increasingly proposed for prevention of ESRD and cardiovascular disease (9,10). This requires solid documenta- tion of a high prevalence of preclinical disease. Thus far, Euro- pean studies on CKD prevalence have been hampered by se- lection bias or incomplete data for defining CKD stages (11–13). Therefore, there is a need for more information on the prev- alence of CKD in European populations as well as a better understanding of the relationship of CKD prevalence to ESRD incidence. The second Health Survey of Nord-Trondelag County (HUNT II) is a large, population-based, cross-sectional study that was conducted in central Norway with a high par- ticipation rate (14). We used HUNT II data to assess the prev- alence of CKD using calibrated serum creatinine values and repeated measurements of albuminuria. Combining these prev- alence estimates with available information on ESRD, health Received December 9, 2005. Accepted May 5, 2006. Published online ahead of print. Publication date available at www.jasn.org. Address correspondence to: Dr. Stein I. Hallan, Department of Medicine, Divi- sion of Nephrology, St. Olav University Hospital, N-7006 Trondheim, Norway. Phone: +47-73867472; Fax: +47-73869390; E-mail: stein.hallan@ntnu.no Copyright © 2006 by the American Society of Nephrology ISSN: 1046-6673/1708-2275