Dissecting and refining the staging of chronic kidney disease.

The current Kidney Disease Outcomes Quality Initiative (KDOQI) staging system of chronic kidney disease (CKD) is simple but too rigid to accommodate variations in renal function observed in the general population. The formula most commonly used to estimate renal function is not validated in subjects without a priori evidence of renal disease. Their combined use results in inappropriate diagnosis of CKD and improbable estimates of prevalence rates. Although this initiative has raised the profile of kidney disease, the exaggeration of the scope of the problem could distract nephrologists from their specialist role. The nephrology community needs a revised staging system for CKD that allows accurate, effective, and timely communication with patients, primary care doctors, public health physicians, and policy makers. Its single most important function will be to identify those patients who will benefit from targeted screening and effective and safe interventions. We offer for discussion a modified definition and staging system of CKD based on the presence of unequivocal, irreversible structural kidney disease, the presence or degree of impairment of kidney function, and the consequences thereof.