Chronic kidney disease

Conceptual model, defi nitions, and outcomes
Figure 1 shows a conceptual model for the development, 
progression, and complications of chronic kidney disease.
1,4
The model includes antecedents associated with increased 
risk, disease stages, and complications including death. 
Risks can be categorised either as susceptibility to kidney 
disease because of sociodemographic and genetic factors, 
or as exposure to factors that can lead to disease. Early 
stages of disease are often asymptomatic, are detected 
during the assessment of comorbid disorders, and can be 
reversible. Rapidly progressive diseases can lead to kidney 
failure within months; however, most diseases evolve over 
decades and some patients do not progress during many 
years of follow-up.
The defi nition of chronic kidney disease is based on 
the presence of kidney damage (ie, albuminuria) or 
decreased kidney function (ie, glomerular fi ltration rate 
[GFR] <60 mL/min per 1·73 m²) for 3 months or more, 
irrespective of clinical diagnosis (panel 1).
1,10,11
Because of 
the central role of GFR in the pathophysiology of 
complications, the disease is classifi ed into fi ve stages 
on the basis of GFR: more than 90 mL/min per 1·73 m² 
(stage 1), 60–89 mL/min per 1·73 m² (stage 2), 
30–59 mL/min per 1·73 m² (stage 3), 15–29 mL/min per 
1·73 m² (stage 4), and less than 15 mL/min per 1·73 m² 
(stage 5). Findings from experimental and clinical 
studies have suggested an important role for proteinuria 
in the pathogenesis of disease progression.
12
Epidemiological studies have shown graded relations 
between increased albuminuria and mortality and kidney 
outcomes in diverse study populations, in addition to, 
and independent of, low GFR and risk factors for 
cardiovascular disease.
13–18
In view of these fi ndings, an