Experts create classification system for leading cause of kidney failure

An international group of medical experts has crafted a much-needed classification system for diabetic nephropathy, the leading cause of total kidney failure, according to a study appearing in an upcoming issue of the Journal of the American Society Nephrology (JASN). The effort should improve communication among health professionals, help researchers design better clinical studies, and guide patient care.

Current estimates suggest that 285 million people worldwide will live with diabetes in 2010 and that the incidence of diabetes will continue to rise. As a result, the incidence of diabetic nephropathy, or kidney damage that arises as a complication of diabetes, will likely increase as well.

Diabetic nephropathy is a complex condition with varying degrees of severity and varying effects on the kidneys. While researchers do not fully understand the mechanisms involved in the development and progression of diabetic nephropathy, they know that too much blood sugar in diabetic patients can damage the clusters of tiny blood vessels in the kidneys that help remove waste from the body. Eventually, the kidney structures begin to leak and kidney failure ensues.

Unlike other kidney conditions, diabetic nephropathy has no standard classification system. Recently, however, a unique cooperative effort among groups of experts from 16 universities spread over seven countries in three continents developed a uniform international classification system that reflects the current understanding of the various forms of diabetic nephropathy. Jan Anthonie Bruijn, MD, PhD (Leiden University Medical Center, the Netherlands), who led the effort, hopes that the classification system will standardize definitions of different classes of diabetic nephropathy and encourage uniform and reproducible reporting of cases among different medical centers.

The new classification system categorizes diabetic nephropathy by varying degrees of severity that will be easy to discern in the clinic. The experts divided the condition into four progressive classes, with the first class being the mildest and the fourth class being the most severe. The system may help guide clinicians as they treat affected patients. In addition, it could aid researchers as they continue to search for the mechanisms involved in the development and progression of diabetic nephropathy.

The classification effort was commissioned by the Research Committee of the nonprofit Renal Pathology Society. Study co-authors include Thijs Cohen-Tervaert, MD, Antien Mooyaart, PhD, Emile de Heer, PhD, Ingeborg Bajema, MD, PhD (Leiden University Medical Center, the Netherlands); Kerstin Amann, MD (University of Erlangen-Nuernberg, in Erlangen, Germany); Arthur Cohen, MD, Mark Haas, MD, PhD (Cedars-Sinai Medical Center); H. Terence Cook, MD (Hammersmith Hospital, in London, UK); Cinthia Drachenberg, MD (University of Maryland , Baltimore); Franco Ferrario, MD (San Carlo Borromeo Hospital, in Italy); Agnes Fogo, MD (Vanderbilt University Medical Center); Kensuke Joh, MD (Sendai-Shaho Hospital, in Sendai-city, Japan) Laure Noël, MD (Hôpital Necker, Université René Descartes, in Paris, France); Jai Radhakrishnan, MD (Columbia University); and Surya Seshan, MD (Weill Cornell Medical College).

Disclosures: The authors reported no financial disclosures.

The article, entitled "Pathologic Classification of Diabetic Nephropathy," will appear online at http://jasn.asnjournals.org/ on February 18, 2010, doi 10.1681/ASN.2010010010.

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Founded in 1966, the American Society of Nephrology (ASN) is the world's largest professional society devoted to the study of kidney disease. Comprised of 11,000 physicians and scientists, ASN continues to promote expert patient care, to advance medical research, and to educate the renal community. ASN also informs policymakers about issues of importance to kidney doctors and their patients. ASN funds research, and through its world-renowned meetings and first-class publications, disseminates information and educational tools that empower physicians.

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