Chronic kidney disease definition and classification: the quest for refinements.

The definition and staging of chronic kidney disease (CKD) have provided a unifying approach to CKD that has generated considerable new information on the epidemiology, course, outcomes, and burden of CKD. Eriksen and Ingebretsen propose a change in the current 3 months chronicity criterion of CKD. Whereas longer lengths of chronicity changed the number of patients in stages 3 and 4, mortality remained high in each of their new groupings. Essentially, CKD persisted and remained a risk multiplier of death.