Comparing the association of GFR estimated by the CKD-EPI and MDRD study equations and mortality: the third national health and nutrition examination survey (NHANES III).
BACKGROUND
The Chronic Kidney Disease Epidemiology Collaboration equation for estimation of glomerular filtration rate (eGFR(CKD-EPI)) improves GFR estimation compared with the Modification of Diet in Renal Disease Study equation (eGFR(MDRD)) but its association with mortality in a nationally representative population sample in the US has not been studied.


METHODS
We examined the association between eGFR and mortality among 16,010 participants of the Third National Health and Nutrition Examination Survey (NHANES III). Primary predictors were eGFR(CKD-EPI) and eGFR(MDRD). Outcomes of interest were all-cause and cardiovascular disease (CVD) mortality. Improvement in risk categorization with eGFR(CKD-EPI) was evaluated using adjusted relative hazard (HR) and Net Reclassification Improvement (NRI).


RESULTS
Overall, 26.9% of the population was reclassified to higher eGFR categories and 2.2% to lower eGFR categories by eGFR(CKD-EPI), reducing the proportion of prevalent CKD classified as stage 3-5 from 45.6% to 28.8%. There were 3,620 deaths (1,540 from CVD) during 215,082 person-years of follow-up (median, 14.3 years). Among those with eGFR(MDRD) 30-59 ml/min/1.73 m(2), 19.4% were reclassified to eGFR(CKD-EPI) 60-89 ml/min/1.73 m(2) and these individuals had a lower risk of all-cause mortality (adjusted HR, 0.53; 95% CI, 0.34-0.84) and CVD mortality (adjusted HR, 0.51; 95% CI, 0.27-0.96) compared with those not reclassified. Among those with eGFR(MDRD) >60 ml/min/1.73 m(2), 0.5% were reclassified to lower eGFR(CKD-EPI) and these individuals had a higher risk of all-cause (adjusted HR, 1.31; 95% CI, 1.01-1.69) and CVD (adjusted HR, 1.42; 95% CI, 1.01-1.99) mortality compared with those not reclassified. Risk prediction improved with eGFR(CKD-EPI); NRI was 0.21 for all-cause mortality (p < 0.001) and 0.22 for CVD mortality (p < 0.001).


CONCLUSIONS
eGFR(CKD-EPI) categories improve mortality risk stratification of individuals in the US population. If eGFR(CKD-EPI) replaces eGFR(MDRD) in the US, it will likely improve risk stratification.
Department of Medicine, Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. tshafi@jhmi.edu
Tariq
T
Shafi
Kunihiro
K
Matsushita
Elizabeth
E
Selvin
Yingying
Y
Sang
Brad C
BC
Astor
Lesley A
LA
Inker
Josef
J
Coresh
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000401:mortality; D003430:Cross-Sectional Studies; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000401:mortality* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D009749:Nutrition Surveys / Q000379:methods* / Q000639:trends; D012307:Risk Factors; D014481:United States / Q000453:epidemiology