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Prevalence of chronic kidney disease in Southern Chinese population - preliminary results of Macau health survey 2006
Un-I Kuok1, Tai-Gen Cui1,2, Li-Rong Meng3
1Renal Department, Centro Hospitalar Conde De S. Januario, Macao SAR China, 2Renal Division and Institute of Nephrology, First Hospital, Peking University, Beijing, China, 3Macao Polytechnic Institute, Macao SAR, China

Background:
Chronic kidney disease (CKD) is a worldwide public health problem. CKD prevalence varies in different regions, countries, and ethic groups. Most studies on CKD prevalence have focused on CKD stages 3-5. In Asia, glomerulonephritis is still the main cause of end stage renal disease, which can be detected in its early stage by urinalysis. A recent study conducted in northern China included urinalysis for detection of CKD. No such study has ever been done in general population in southern China.

Methods:
Prevalence of renal replacement therapy (RRT) in Macau was derived from data registry in renal department of CHCSJ. Prevalence of CKD was derived from a community study, in which 3000 people aged above 18 years were randomly selected from general population in Macau in 2006. Participants were interviewed for anthropometric data collection and questionnaire filled out for relevant information. Fresh urine samples were collected and immediately tested with dipsticks. Fasting blood samples were collected and then transferred to the central laboratory for measurement of biochemical variables. Glomerular filtration rate (eGFR) was estimated using the simplified MDRD equation, and CKD was defined as an eGFR<60 ml/min/1.73m2 and/or evidence of kidney damage (defined as proteinuria and/or hematuria).

Results:
Preliminary results derived from analysis of data of 1047 people are reported here. The overall CKD prevalence was 21.3%. The prevalence of CKD stages 3-5 (eGFR < 60 ml/min/1.73m2) was only 3.3%. Kidney damage manifested as abnormal urinalysis accounted for most of the total CKD prevalence (18%). Of the 34 people with eGFR <60ml/min/1.73m2, 33 were over 40 years old. The age-specific prevalence of CKD stages 3-5 was 0.1%, 4%, and 21.2% for age ranges 18-39, 40-64 and ｳ 65 years respectively. A total of 195 (18.6%) people has proteinuria and/or hematuria, 153 (78.5%) of them were female. Isolated hematuria and proteinuria were found in 136 and 48 people respectively, whereas both were present in the other 11. By the end of year 2006, total 448 people (933 per million population) were receiving RRT in Macau, including 145 on peritoneal dialysis, 224 on hemodialysis and 79 had undergone kidney transplantation.

Conclusions:
Prevalence of advanced CKD is relatively low in general population in Macau, but a surprisingly high prevalence show abnormalities on urinalysis. Studies are required to validate the finding and exclude the possibility of false positivity of dipstick urine test.