Staging of chronic kidney disease: time for a course correction.

Awareness of chronic kidney disease (CKD) has increased in part because of the definitions and treatment guidelines set out by Kidney Disease Outcomes Quality Initiative (KDOQI); however, the staging system set forth by these guidelines has led to several problems and unforeseen consequences. Stages 1 and 2 CKD are difficult to determine using the standard Modification of Diet in Renal Disease (MDRD) estimation of GFR, and their clinical significance in the absence of other risk factors is unclear. Just because microalbuminuria in people without diabetes is a cardiovascular risk factor does not make it kidney disease. Most patients who receive a diagnosis of stage 3 CKD (GFR between 30 and 59 ml/min) are elderly people, and the vast majority of these patients will die before they reach ESRD. The staging system needs to be modified to reflect the severity and complications of CKD. It is suggested that stages 1 and 2 be eliminated and stages 3, 4, and 5, be simply termed moderate impairment, severe impairment, and kidney failure, respectively. In addition, age should be a modifying factor, especially in moderate kidney impairment. These changes would allow identification and treatment of clinically relevant disease and avoidance of what can seem exaggerated prevalence estimates.