A new definition and classification of chronic kidney disease adds proteinurinea to kidney function to predict progression, and split Grade 3 into two levels to stress when patients are at risk.
Kidney Disease: Improving Global Outcomes (KDIGO) released the definition and classification online Jan. 4 and published them as a supplement in the January 2013 issue of Kidney International.
The evidence-based clinical practice guideline adds an estimation of the level of protein in the urine to the assessment of kidney function, based on estimated glomerular filtration rate. The new classification system also addresses the cause of kidney disease.
The guidelines state, "We propose that this classification of CKD by Cause, GFR and Albuminuria, respectively be referred to as CGA staging. It can be used to inform the need for specialist referral, general medical management, and indications for investigation and therapeutic interventions. It will also be a tool for the study of the epidemiology, natural history, and prognosis of CKD.
The guidelines also add two levels to Grade 3 disease: G3a, 45 to 59 GFR mL/min/1.73m2, mildly to moderately decreased, and G3b, 30 to 44 GFR mL/min/1.73m2, moderately to severely decreased.
KDIGO co-chair Bertram Kasiske, MD, FACP, of the University of Minnesota, said in a press release that, "For a decade we have used a simple chart to divide kidney disease into five categories based on the kidney's ability to filter blood. This has staged the severity of disease, but not the risk of progression."
"This new system overlays urinary protein levels with glomerular filtration rates to produce a risk grid. These two factors are much better predictors of worsening kidney disease than either are alone," Dr. Kasiske added.