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Prevalence of chronic kidney disease in a population presenting for health screening in Singapore
Boon Wee Teo1, Sunil Sethi2, Evan JC Lee1
1Division of Nephrology, Department of Medicine, 2Department of Laboratory Medicine, Yong Loo Lin School of Medicine, National University Singapore, Singapore

Objective
To determine the prevalence of chronic kidney disease (CKD) in a population voluntarily presenting for health screening to an academic medical center in 2006.

Methods
A retrospective analysis was performed on data from patients presenting for health screening in 2006 at the National University Hospital. De-identified data was abstracted from the laboratory computer database including age, gender, race, and serum creatinine. Serum creatinine (_mol/L) was measured by the Jaffe method. The estimated glomerular filtration rate (eGFR in mL/min/1.73m2) was calculated using the abbreviated MDRD equation. CKD was classified into stages according to eGFR using the National Kidney Foundation guidelines.

Results
Data of 2112 patients was examined. The mean age was 47.3 ± 25.6 years, mean serum creatinine 78.6 _mol/L± 25.6 , and mean eGFR= 91.2 mL/min/1.73m2 ｱ 22.2. There were 51.5% male patients. Racial composition of the population included 60.5% Chinese, 2.7% Indian, 1.1% Malay, 1.1% Caucasian, and 34.3% classified as other. Overall, 1.6% of patients had creatinine above the upper limit of laboratory normal (65-125 _mol/L), and 4.1%, 0.3%, and 0.05% of patients had stage 3, 4, and 5 CKD respectively. The Chinese sub-population had 3.5%, 0.23%, and 0.08% of patients with stage 3, 4, and 5 CKD respectively; while the non-Chinese sub-population had 4.1%, 0.48%, and 0% of patients with stage 3, 4, and 5 CKD respectively.

Conclusion
In 2006, only 33 patients (1.6%) had serum creatinine above the normal laboratory range. Using estimated GFR, 94 patients (4.5%) had stage 3 to 5 CKD. Therefore, using serum creatinine alone may underestimate the prevalence of chronic kidney disease in a population presenting for health screening.

Keywords:
Chronic kidney disease, glomerular filtration rate, creatinine, Singapore, prevalence, health screening