title: The choice of estimating equations for glomerular filtration rate significantly affects the prevalence of chronic kidney disease in a multi-ethnic population during health screening.
abstract: BACKGROUND
  Patients present to the National University Hospital of Singapore and select one of several health screening packages after counselling. The prevalence of chronic kidney disease (CKD) in this population when different glomerular filtration rate (GFR) estimating equations are used has not been examined.
  
  
  METHODS
  Demographic data and urinalyses of patients from 2000 to 2005 were extracted from laboratory computer databases and analysed. CKD was classified into stages according to the US National Kidney Foundation guidelines by eGFR (mL/min per 1.73 m(2)) using the four-variable Modification of Diet in Renal Disease equation. GFR of ethnic Chinese was also estimated using Ma's equation 8 (cGFR). Stage 1 and normal (eGFR or cGFR > 90) was discriminated by urinary microscopy or dipstick for proteinuria, albuminuria, hematuria or leukocyturia.
  
  
  RESULTS
  There were 3979 screenings (55.9% males, 61.9% Chinese). Means: age = 47.0 +/- 12.3 years, creatinine = 80.1 +/- 26.5 micromol/L, eGFR = 89.6 +/- 19.7, cGFR = 110.8 +/- 23.8 and (eGFR + cGFR) = 102.5 +/- 24.9. By eGFR in all patients, the prevalence of CKD was 45.7%, 50.6%, 3.3%, 0.3% and 0.08% for stages normal or 1, 2, 3, 4 and 5, respectively. For Chinese patients only, eGFR and cGFR resulted in a different distribution (eGFR%/cGFR%): 24.9/50.5, 15.2/29.3, 56.8/19.7, 3/0.8, 0.2/0.2, 0/0 for stages 'Normal', 1, 2, 3, 4 and 5, respectively (P < 0.001).
  
  
  CONCLUSIONS
  The prevalence of moderate to severe CKD (stage 3 to 5) in patients presenting for health screening in Singapore was 3.7%. Notably, the prevalence of mild to moderate CKD (stages 1, 2 and 3) in Chinese patients was affected significantly by the choice of GFR estimating equation.
authors.affiliation: Department of Medicine, Yong Loo Lin School of Medicine, Singapore. mdctbw@nus.edu.sg
authors.forename: Boon W
authors.initials: BW
authors.lastname: Teo
authors.forename: Zhi Y
authors.initials: ZY
authors.lastname: Ng
authors.forename: Jialiang
authors.initials: J
authors.lastname: Li
authors.forename: Sharon
authors.initials: S
authors.lastname: Saw
authors.forename: Sunil
authors.initials: S
authors.lastname: Sethi
authors.forename: Evan J C
authors.initials: EJ
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000453:epidemiology* / Q000208:ethnology / Q000652:urine; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012846:Singapore / Q000453:epidemiology / Q000208:ethnology