| Background:The chronic kidney disease (CKD) had become a leading public health problem in the world. End-stage renal disease (ESRD) receiving renal replacement therapy has been rising rapidly, for example the number of ESRD increased from41700to324000in the past13years in China. Meanwhile CKD was associated closely with cardiovascular disease (CVD) and the prevalence of CVD increased dramatically with the progress of chronic kidney disease. The complications of CKD including anemia, hypertension, calcium-phosphorus disorders, and renal bone disease also increased the mortality and reduced the quality of life for patients of CKD.Previous studies had shown that chronic glomerular disease was the first cause of CKD in China, but in recent years China had experienced rapid development of socio-economy, resulting in change of standard of living, eating habits and lifestyle with higher fat intake and less physical activities which had promoted the rising of the chronic disease such as hyperuricemia and metabolic syndrome (hypertension, diabetes, lipid abnormalities and obesity). A large number of studies had found that the metabolic syndrome, hyperuricemia were becoming the major cause of CKD. The underlying mechanisms of MS mediating pathological and pathophysiological change in the kidney included insulin resistance, inflammation, altered renal hemodynamic, oxidative stress, endothelial dysfunction, and the sympathetic nervous system (SNS). Hyperuricemia stimulated expression of cyclooxygenase (COX-2), synthesis of macrophage chemotactic factor-1(MCP-1), activation of rennin angiotensin aldosterone system (RASS) and decrease of nitric oxide (NO) syntheses, which led to inflammation and fibrosis of renal interstitial, thicken of the afferent arterioles and macrophage infiltration, increase of system and local blood pressure. A cross-sectional survey of a nationally representative sample of Chinese adults showed: the number of patients with CKD was estimated to be about119.5million, the prevalence of CKD varied greatly between geographical and the awareness rate of CKD was lower. The factors independently associated with kidney damage were hypertension, diabetes, hyperuricemia, economic status. There was an urgent need for further investigation of prevalence and risk factors of CKD, increasing the awareness rate of CKD, developing preventive and therapeutic approaches to CKD, reducing the risk of ESRD and concurrent disease.There were some disadvantages in community-based epidemic study:the respondent’s poor adherence, lower cost-benefit ratio, the lack of qualified kidney specialists, being hard to draw a causal link between independent variable and dependent variable in cross-sectional study and so on. Our study was supported by EU FP7Program, Anhui province natural science fund. Clinical data of undergoing routine checkups at the Yijishan Hospital of Wannan Medical College were analyzed in this cross-sectional study. We investigated the prevalence of and risk factors associated with CKD, the relation between CKD and MS, hyperuricemia in Wuhu, China. Aim to strengthen the education, provide the measures for preventive and therapeutic approaches to CKD, and help the hygiene department of Wuhu to make a reasonable public health policy. In the future we would follow up the high-risk population and CKD patients in order to assess the progress and control of CKD, various interventions on the CKD, and explored the causal relationship between the risk factors and CKD taking advantage of the characteristics of the regular health checkup and well-kept data-base.Estimating glomerular filtration rate (eGFR) formula was derived from regression analysis in which the level was related to the serum concentration of an endogenous filtration marker such as serum creatinine. Age, gender, diet, weight and laboratory testing method affected serum creainine concentration independently from GFR. Because the eGFR formula was from different development datasets and race, it did not apply to all people to evaluate renal function. No formula would be free of bias in the survey of the prevalence of CKD in all settings and populations, it was obligatory to compare the different eGFR equation in the epidemiological studies. In this study, we investigated the impact of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Chinese the Modification of Diet in Renal Disease (C-MDRD) on the prevalence of CKD.Objective1. To investigate the difference in prevalence of eGFR<60ml/min/1.73m2by using C-MDRD and CKD-EPI equations respectively and assess the impact of C-MDRD and CKD-EPI eqution on the estimation of GFR in different gender and age group.2. To investigate the prevalence of chronic kidney disease (CKD) and associated risk factors in adult health checkup population in Wuhu City.3. To investigate the prevalence of MS in elderly health checkup, and the relationship between MS or its components and CKD.4. To investigate the prevalence of HUA in elderly health checkup population, evaluating whether the serum uric levelwas associated with CKD and hypertension.Methods1. Prevalence of CKD and associated risk factor inan annual health checkup population.In this cross-sectional study, data was collected from40,348residents (aged18to92years old) between January2010and June2011. Serum laboratory tests and urine dipstick/urinalysis were performed on all participates. All the participants were categorized by age into six groups according to decade (<30,30-39,40-49,50-59,60-69, and≥70years). Clinical datawas obtained from the hospital’s health checkup center. All participants underwent an overnight fasting (at least12hours, low fat, without alcohol) prior to collection of venous blood samples. Gender, birthdates, and medications were recorded. Height, weight, and blood pressure were also measured by trained nurses, and entered into the database. Dipstick testing of the first morning fresh urine was performed. A urinary protein level of1+or greater was considered abnormal. Hematuria (>=1+red blood cells) were confirmed by microscopic analysis.Three or more red blood cells observed in a high-power field (HPF) were considered abnormal.Menstruating women were not considered to have abnormal hemograms. Laboratory testing of venous blood was obtained for glucose, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), uric acid, and creatinine levels (LH hematology analyzer). Serum creatinine was measured by ammonia iminohydrolase method. All samples were analyzed in the hospital’s clinical laboratory.eGFR was calculated by the C-MDRD equation and CKD-EPI equation as follows. C-MDRD equation which was validated for the Chinese population as follows:eGFR (ml/min/1.73m2)=175xScr (mg/dl)-1234×age (years)0.179[femalex0.79] CKD-EPI:eGFR (ml/min/1.73m2)=141×min(Scr/k,1) a×max(Scr/k,1)-1.209×0.993age×1.018(if female)。where Scr is serum creatinine, k is0.7for female and0.9for males,a is-0.329for female,-0.411for male。 min indicates the minimum of Scr/K or1, max indicates the maximum of Scr/K or1.According to the Kidney Disease Outcomes Quality Initiative (K/DOQI) classification system, an eGFR of less than60ml/min/1.73m2and/or proteinuria and/or hematuria to be indicators of CKD.2. The relationship between either metabolic syndrome orhyperuricemia and CKD Among above health checkup population, a total of24095participates of subpopulation older than40years were analyzed, including male14616and female9479, and their eGFR was calculated by the C-MDRD equationThe Chinese Diabetes Society criteria (CDS) in2004were used to define metabolic syndrome in the present study. According to the ADS criteria, participants were classified as having MS if they had three abnormalities or more for those items shown below:a) Obesity:body mass index (BMI)≥24kg/m2;b) Raised fasting glucose:overnight≥6.1mmol/L, or previously diagnosed type2diabetes;c) Hypertension:systolic blood pressure≥140mmHg, or diastolic blood pressure≥90mmHg or treatment of previously diagnosed hypertension;d) Lipid abnormality:triglyceridemia concentration≥1.7mmol/L and/or HDL-cholesterol concentration<0.9mmol/L for male or<1.0mmol/L;Hyperuricemia was defined as a serum uric acid level higher than420μmol/1in males or360μmol/1in femalesCKD was defined as an eGFR of less than60ml/min/1.73m2and/or proteinuria excluding hematuria. Statistical analysisData were presented as the mean±standard deviation for continuous variables and as proportions for categorical variables. Differences between groups wasexamined using Pearson’s chi-squared test for categorical variables and the two-tailed paired Student’s t-test for continuous data. The kappa test for agreement: kappa statistic(k)0.21-0.40is considered fair agreement,0.41-0.60moderate agreement,0.61-0.80substantial agreement and0.81-1.00near-perfect agreement. Multivariate binary logistic regression analysis was used to estimate odds ratios (ORs) by comparing CKD occurrence and associated factors. A p-value of less than0.05was considered to be statistically significant. SPSS version11.5software (SPSS Inc., Chicago, IL, USA) was used for data analysis.Result1Comparison of C-MDRD and CKD-EPI equation in health checkup in Wuhu citya) C-MDRD eGFR was higher than CKD-EPI eGFR in the whole population(84.56±13.83vs.88.48±13.83ml/min/1.73m2, P＜0.001), Theaverage difference between the C-MDRD and CKD-EPI equation was0.074±3.83ml/min/1.73m2. The prevalence of eGFR<60ml/min/1.73m2was2.2%when GFR was estimated by C-MDRD equation. The prevalence was significantly lower than the prevalence calculatedby CKD-EPI equation (3.6%). However, kappa statistics showed very good agreement between the two equations(k=0.708). Results given by the two equations was highly correlated(r=0.729).b) Inter-subpopulations comparison was conducted according to sex and age. In the younger group(<60years old), Theaverage difference between the C-MDRD and CKD-EPI equations was0.57±3.38ml/min/1.73m2. The prevalence of eGFR<60ml/min/1.73m2calculated by C-MDRD equation was lower than CKD-EPI (1.2%vs.1.4%, P<0.001=. Kappa statistics showed very good agreement between the two equations (k=0.815) and highly correlated(r=0.816).c) In those aged≥60years old, theaverage difference between the eGFR calculated respectively by C-MDRD and CKD-EPI equation was5.56±2.77ml/min/1.73m2. The prevalence of eGFR<60ml/min/1.73m2by C-MDRD equationwas lower than CKD-EPI (11.1%vs.23.0%, P<0.001=and agreementthe results of the equations was fair(k=0.59) and correlated (r=0.647).2Prevalence of CKD and associated factor in the annual health checkup populationa) The mean age of all participates was43.25±12.73years old, and43.62±12.81for male,42.66±12.63for female. The crude and age-adjusted prevalence of CKD was3.7%,4.5%and the age-standardized prevalence of eGFR<60ml/min/1.73m2, proteinuria and hematuria were2.84%,2.21%,2.12%respectively. The prevalence of CKD in female was significantly higher than in male(4.2%vs3.0%, P<0.001=.b) The prevalence of other chronic disease:the age-standardized prevalence of obesity3.54%, anemia6.7%, hypercholesterolemia9.26%, hypertriglyceridemia24.71%, hyperuricemia being14.76%, diabetes being4.24%, hypertension being19.72%, Low high-density lipoprotein-C being16.21%respectively. The prevalence of obesity, hypercholesterolemia, hypertriglyceridemia, increasd low density lipoprotein cholesterol (HDL-C), hyperuricemia, diabetes in male was respectively higher than female (P<0.01), the prevalence of anemia in male was lower than female (P<0.01).c) The logistic regression analysis showed:the elderly(≥60years), hyperuricemia, diabetes, hypertension, anemia and obesity were independently associated with CKD.3Relationship between metabolic syndrome and CKD among population older than40years in the annual health checkup populationa) The number of participates aged40years or older, were24095in the study. The mean age of these participatess was51.49±9.16years old,51.69±9.40for male (60.7%) and51.18±8.78for female (39.3%).b) The prevalence and age-standardized prevalence of metabolic syndrome was14.1%and14.7%respectively. It was higher in male than in female (18.19%vs.9.7%, P<0.001), the prevalence of metabolic syndrome wasn’t different in male when grouped by age but was different in female when grouped by age.c) The prevalence of CKD was significantly higher among those compared to the their counterparts without the metabolic syndrome (10.4%vs.4.5%, P<0.001=.d) The logistic regression analysis showed:MS, age (↑10years) and male were independently associated with CKD (OR:2.29;1.89and1.20), meanwhile the OR of CKD subpopulation with younger age (<60years old) was higher than the elderly.e) Age, sex-adjusted and multivariate-adjusted logistic analysis showed the ORs for CKD ofobesity(OR:1.19,95%CI:1.06-1.35), hypertriglyceridemia(OR:1.36,95%CI:1.20-1.54), low HDL-C(OR:1.25;95%CI:1.01-1.54), hypertension(OR:1.72;95%CI:1.53-1.94), diabetes(OR:1.39;95%CI: 1.74-2.41) were risk factors of CKD. There was a significant correlation relationship between the number of metabolic syndrome components and the prevalence of CKD. The residents with1,2,3and4or5component of the MS had a1.45,1.34、1.42and1.39-fold increased odds of CKD, respectively, compared with those without any MS component.4Relation between hyperuricemia and CKDa) The crude prevalence and age-standardized prevalence of hyperuricemia was16.0%a nd15.59%respectively. The prevalence of it was21.6%in males which was significantly higher than in females(7.3%) and age-standardized prevalence of hyperuricemia for males and femaleswas22.14%,10.10%respectively, meanwhile the prevalence of it increased with the age, especial in female particular those older than50years of age in female.b) The prevalence of CKD in participates with serum uric acid levels in the first, second, third and fourth quartiles were2.1%,3.4%,4.7%and2.9%;2.7%,3.3%,4.1%and9.9%in male;2.0%,3.5%,7.1%and25.5%in female.c) Compared to the participates with a serum uric acid level at thefirst quartile, the multivariate-adjusted odds for CKD of the second, third and fourth quartiles were1.48(95%CI:1.16-1.90),1.51(95%CI:1.37-1.80),2.23(95%CI:2.03-2.43), the multivariate-adjusted odds for proteinuria being1.04(95%CI:0.71-1.52),1.04(95%CI:0.85-1.28),1.36(95%Cl:1.17-1.57) and multivariate-adjusted odds for low-eGFR being1.64(95%CI:1.17-2.47),1.93(95%Cl:1.58-2.36) respectively. When serum uric acid was analyzed a continuous variable, we observed a positive correlationwith eitherCKD, proteinuria or low-eGFR.d) The hyperuricemia was independently associated with hypertension (OR:1.17,95%Cl:1.13-1.21). Compared to the participates with serum uric acid at the first quartile, the multivariate-adjusted odds for CKD of the second, third and fourth quartiles were1.11(95%CI:1.00-1.24),1.51(95%CI:1.10-1.24),1.15,95%CI:1.10-1.21) respectively.Conclusion1. C-MDRD equation reduced the calculated prevalence of eGFR<60ml/min/1.73m2, especial in those aged≥60years old. Such discrepancies were of importance and should be confirmed and explained by additional studies using GFR measured with a reference methods.2. The prevalence of proteinuria or decreased eGFR was relatively lower in the health checkup populationover18years in Wuhu city. The age, anemia, hyperuricemia, hypertension, diabetes, lipid abnormality and obesity were all independently associated with CKD.3. In the Wuhu health checkup residents aged over40years old, metabolic syndrome was significantly associated with CKD. Hypertension, diabetes, low HDL-C, hypertriglyceridemia and obesity were independently associated with CKD, particularly diabetes and hypertension. There was linear relationship between the number of metabolic syndrome components and CKD.4. The prevalence of hyperuricemia was higher in the health checkup residents aged over40years old. Hyperuricemia was associated with increased prevalence of hypertension and CKD.5. It is suggested to be urgent to ensure health diet, proper exercise, correcting poor eating habits, weight control. It is essential for hygience departments to screen the CKD and high-risk population, controlling chronic diseases such as hypertension, diabetes, obesity and lipid disorders in order to reduce the occurrence of cardiovascular disease and CKD events. |
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