Comparison of the prevalence and mortality risk of CKD in Australia using the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) Study GFR estimating equations: the AusDiab (Australian Diabetes, Obesity and Lifestyle) Study.
BACKGROUND
The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) is more accurate than the Modification of Diet in Renal Disease (MDRD) Study equation. We applied both equations in a cohort representative of the Australian adult population.


METHODS
Population-based cohort study.


METHODS
11,247 randomly selected noninstitutionalized Australians aged >or= 25 years who attended a physical examination during the baseline AusDiab (Australian Diabetes, Obesity and Lifestyle) Study survey.


METHODS
Glomerular filtration rate (GFR) was estimated using the MDRD Study and CKD-EPI equations. Kidney damage was defined as urine albumin-creatinine ratio >or= 2.5 mg/mmol in men and >or= 3.5 mg/mmol in women or urine protein-creatinine ratio >or= 0.20 mg/mg. Chronic kidney disease (CKD) was defined as estimated GFR (eGFR) >or= 60 mL/min/1.73 m(2) or kidney damage. Participants were classified into 3 mutually exclusive subgroups: CKD according to both equations; CKD according to the MDRD Study equation, but no CKD according to the CKD-EPI equation; and no CKD according to both equations. All-cause mortality was examined in subgroups with and without CKD.


METHODS
Serum creatinine and urinary albumin, protein, and creatinine measured on a random spot morning urine sample.


RESULTS
266 participants identified as having CKD according to the MDRD Study equation were reclassified to no CKD according to the CKD-EPI equation (estimated prevalence, 1.9%; 95% CI, 1.4-2.6). All had an eGFR >or= 45 mL/min/1.73 m(2) using the MDRD Study equation. Reclassified individuals were predominantly women with a favorable cardiovascular risk profile. The proportion of reclassified individuals with a Framingham-predicted 10-year cardiovascular risk >or= 30% was 7.2% compared with 7.9% of the group with no CKD according to both equations and 45.3% of individuals retained in stage 3a using both equations. There was no evidence of increased all-cause mortality in the reclassified group (age- and sex-adjusted hazard ratio vs no CKD, 1.01; 95% CI, 0.62-1.97). Using the MDRD Study equation, the prevalence of CKD in the Australian population aged >or= 25 years was 13.4% (95% CI, 11.1-16.1). Using the CKD-EPI equation, the prevalence was 11.5% (95% CI, 9.42-14.1).


CONCLUSIONS
Single measurements of serum creatinine and urinary markers.


CONCLUSIONS
The lower estimated prevalence of CKD using the CKD-EPI equation is caused by reclassification of low-risk individuals.
The George Institute for International Health, Sydney, NSW, Australia. swhite@george.org.au
Sarah L
SL
White
Kevan R
KR
Polkinghorne
Robert C
RC
Atkins
Steven J
SJ
Chadban
D001315:Australia / Q000453:epidemiology; D002908:Chronic Disease; D015331:Cohort Studies; D003928:Diabetic Nephropathies / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000150:complications / Q000178:diet therapy / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology*; D008019:Life Style; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D015995:Prevalence; D012307:Risk Factors