No abstract

Chronic kidney disease (CKD) is a worldwide public health problem, with adverse outcomes of kidney failure, cardiovascular disease (CVD), and premature death. A simple definition and classification of kidney disease is necessary for international development and implementation of clinical practice guidelines. Kidney Disease: Improving Global Outcomes (KDIGO) conducted a survey and sponsored a controversies conference to (1) provide a clear understanding to both the nephrology and nonnephrology communities of the evidence base for the definition and classification recommended by Kidney Disease Quality Outcome Initiative (K/DOQI), (2) develop global consensus for the adoption of a simple definition and classification system, and (3) identify a collaborative research agenda and plan that would improve the evidence base and facilitate implementation of the definition and classification of CKD. The K/DOQI definition and classification were accepted, with clarifications. CKD is defined as kidney damage or glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) for 3 months or more, irrespective of cause. Kidney damage in many kidney diseases can be ascertained by the presence of albuminuria, defined as albumin-to-creatinine ratio >30 mg/g in two of three spot urine specimens. GFR can be estimated from calibrated serum creatinine and estimating equations, such as the Modification of Diet in Renal Disease (MDRD) Study equation or the Cockcroft-Gault formula. Kidney disease severity is classified into five stages according to the level of GFR. Kidney disease treatment by dialysis and transplantation should be noted. Simple, uniform classifications of CKD by cause and by risks for kidney disease progression and CVD should be developed.

Impaired renal function (GFR(c)) is a stronger predictor of mortality than impaired cardiac function (LVEF and New York Heart Association class) in advanced CHF, and it is associated with increased levels of N-terminal ANP. Moreover, impaired renal function was not related to LVEF, which suggests that factors other than reduced cardiac output are causally involved.

Antihypertensive regimens that include ACE inhibitors are more effective than regimens without ACE inhibitors in slowing the progression of nondiabetic renal disease. The beneficial effect of ACE inhibitors is mediated by factors in addition to decreasing blood pressure and urinary protein excretion and is greater in patients with proteinuria. Angiotensin-converting inhibitors are indicated for treatment of nondiabetic patients with chronic renal disease and proteinuria and, possibly, those without proteinuria.

Limited data are available on the independent associations of estimated glomerular filtration rate (eGFR) and albuminuria with mortality and end stage renal disease (ESRD) among individuals with chronic kidney disease (CKD). We conducted a collaborative meta-analysis of 21,688 participants selected for CKD from 13 cohorts. After adjustment for potential confounders and albuminuria, a 15 mL/min/1.73 m2 lower eGFR below 45 mL/min/1.73 m2 was significantly associated with mortality (pooled hazard ratio [HR] 1.47 [95% CI: 1.22–1.79]), and ESRD (pooled HR 6.24 [95% CI: 4.84–8.05]). There was significant heterogeneity between studies for both HR estimates. After adjustment for risk factors and eGFR, an eight-fold higher albumin:creatinine ratio (ACR) or protein:creatinine ratio (PCR) was significantly associated with mortality (pooled HR 1.40 [95% CI: 1.27–1.55]), without evidence of significant heterogeneity. An eight-fold higher ACR or PCR was also strongly associated with ESRD (pooled HR 3.04 [95% CI: 2.27–4.08]), with significant heterogeneity between HR estimates. Lower eGFR and more severe albuminuria independently predict mortality and ESRD among individuals selected for CKD. The associations are stronger for ESRD than for mortality. The observed associations are consistent with CKD classification based on eGFR stages, and suggest that albuminuria provides additional prognostic information among individuals with CKD.