Of the 6000 participants involved in this study, 5231 had a complete data set and were entered into our statistical analysis. Their demographic and clinical characteristics are shown in Table 1. The prevalences of hypertension, dyslipidemia, hyperuricemia and diabetes were 34.6%, 14.6%, 11.5% and 7.6%, respectively. A total of 80.3% of the participants attended senior high school. The prevalences of current smokers and habitual drinkers were similar. The mean eGFR was 92.6 ± 21.5 mL/min/1.73 m2, and the median ACR was 14.1, with an interquartile range of 8.8 to 23 mg/g. Generally, participants with reduced eGFR or albuminuria were older, primary educated, and performed heavy physical activities. They had a lower proportion of high fat diet and higher prevalences of cardiovascular disease, hypertension, dyslipidemia, hyperuricemia and diabetes than did those without indicators of renal damage.
There were 132 subjects exhibiting an eGFR less than 60 mL/min/1.73 m2 and 858 subjects exhibiting albuminuria (Table 2). A total of 945 subjects had CKD and 92 of them were DKD patients. The adjusted prevalence of reduced eGFR was 2.8% (95% CI = 2.4 – 3.3%) and that of albuminuria was 14.9% (95% CI = 13.9 – 15.9%). The overall adjusted prevalences of CKD and DKD were 16.8% (95% CI = 15.8 – 17.8%) and 1.8% (95% CI = 1.4 – 2.1%), respectively. By disease stage, the prevalence was as follows: stage 1, 6.0%; stage 2, 7.8%; stage 3a, 2.4%; stage 3b, 0.2%; stage 4, 0.3% and stage 5, 0.1%. In subjects with normal eGFR, the numbers with stages A1 – A3 were 4286, 743 and 70, respectively. As shown in figure 1, the prevalence of reduced eGFR was much higher in women over 40 years old than in their male counterparts, and the overall prevalence was higher with older age in both men and women. The prevalence of albuminuria was higher in older participants and in women than men in all age groups except for women subjects who aged 60 – 69 years old (24.7 versus 26.3%). Generally, the prevalences of CKD and DKD increased along with age in men and women subjects. In addition, subjects with both hypertension and diabetes shows the highest prevalences of reduced eGFR (7.3% 95% CI = 4.0 – 10.5%) and albuminuria (54.8% 95% CI = 48.6 – 61.1%) than whom with either hypertension or diabetes (Figure 2).
Comparing with those who have no renal damages, subjects with reduced eGFR performed an older age, more women individuals, insufficient consumption of meat and physical activity, poor control of diabetes and more hypertension and dyslipidemia, while those with albuminuria tended to exhibit poor control of diabetes and more dyslipidemia (Table 3). Twenty-five subjects were classified as stage 3 – 5 CKD, and 181 subjects had albuminuria (Table 4). The prevalence of reduced eGFR was 6.3% (95% CI = 3.9 – 8.6%), and that of albuminuria was 45.3% (95% CI = 40.4 – 50.1%). The overall prevalence of CKD in diabetic subjects was 48.0% (95% CI = 43.1 – 52.9%). By disease stage, the prevalence was as follows: stage 1, 15.8%; stage 2, 26.0%; stage 3a, 2.0%; stage 3b, 0.8%; stage 4, 0.5% and stage 5, 0.3%. In subjects with normal eGFR, the numbers with stages A1 – A3 were 209, 139 and 28, respectively.
The prevalence of reduced eGFR was not significantly different among the three tertiles of education and family income, while that of albuminuria was highest in subjects in the lower tertile of education and upper tertile of family income (Table 5). The overall adjusted prevalences of CKD were 33.5% (95% CI = 27.7 – 39.3%) and 26.5% (95% CI = 22.4 – 30.6%), respectively. The prevalences of hypertension and diabetes were lower in subjects with higher education conditions, while they were lowest in subjects in the middle tertile of family income. Poor control of hypertension and diabetes was most prevalent in subjects in the upper tertile of education (6.9% and 29.9%, respectively) and middle tertile of family income (9.3% and 27.4%, respectively).
The results of the binary logistic regression are shown in Table 6. Older age, higher education, and hypertension were all independently associated with a higher risk of reduced eGFR, while male gender showed the opposite association. Factors independently associated with a higher risk of albuminuria were older age, being a current smoker, a diet rich in fruits and vegetables, overweight, obesity, diabetes, hypertension and dyslipidemia. Higher education level and more consumption of meat were associated with lower ORs of developing albuminuria than the other factors. In addition, being male and over 40 years of age, high level physical activity, obesity, dyslipidemia and hyperuricemia were significantly associated with an increased risk of DKD.
In the ordinal logistic regression, the data were analyzed in two models (Table 7). In model one, age, smoking, a diet rich in fruits and vegetables, heavy physical activity, high BMI, diabetes, hypertension, and dyslipidemia were positively associated with increased severities of albuminuria in subjects with normal eGFR values, while a higher education level and a diet rich in meat were associated with reduced severities. Similarly, in model two, a higher education level and a high-fat diet were also negatively correlated with an elevated risk of renal damage, while older age, being a current smoker, a diet rich in fruits and vegetables, obesity, diabetes, hypertension and dyslipidemia showed a positive association.