Prevalence and Cardiovascular Risk Profile of CKD
In the OEC/HES, 8693 persons out of the planned sample of 9020 underwent interviews and examinations (96.4%). Information on ACR or serum creatinine was lacking in 1141 individuals. Thus, CARHES included 7552 Caucasian subjects (84% of the planned sample). In the sample, 28 persons with eGFR <60 mL/min/1.73 m did not have ACR measured; therefore, the evaluation of distribution of albuminuria by eGFR category was obtained in 7524. The general characteristics of the whole population are reported in Table 1.
Table 2 describes unadjusted prevalence estimates of CKD. Overall, prevalence of CKD increased remarkably across age strata, from 2.7% at age 35–49 years to 17.0% at 70–79 years. Early stages of disease accounted for most of the estimated CKD population, the prevalence of the first two CKD stages (4.16%) being higher than that of CKD Stage G3a–5 (2.89%). In particular, persons with eGFR <45 mL/min/1.73 m (Stage G3b–5) represented only 0.78% of the whole population and the 11% of the CKD population. Prevalence of CKD was similar in North [7.0% (95% CI 6.1–7.9)], Centre [5.6% (95% CI 4.3–7.0)] and South [7.8% (95% CI 6.8–8.8)]. When considering the prevalence rates of single stages of disease by gender, we observed a higher prevalence of early—albuminuric—stages in males, with the difference being not maintained in the more advanced stages of disease, G3a–5. Questionnaire-reported awareness of CKD was poor with 10.0% of person with CKD being aware of their condition; awareness increased to 18.4% in those with eGFR <60 mL/min/1.73 m.
CKD prevalence slightly decreased after age standardization to the resident population (overall: 6.29%, 95% CI 5.74–6.84, CKD Stage G1–2 A2–3: 3.78%, 95% CI 3.36–4.22; CKD Stage G3a–5: 2.50%, 95% CI 2.15–2.85), with men showing higher rates of Stage G1–2 A2–3 (4.2 versus 3.4% in females) and slightly lower rates of Stage G3a–5 (2.1 versus 2.8% in females). We can therefore estimate that, in Italy, there is a total number of 2 180 542 adult persons (age 35–79 years) with CKD (1 075 354 men and 1 105 187 women), most with early disease (60.4%) and older age (69.8%; Supplementary data, Table SA http://ndt.oxfordjournals.org/content/30/5/806/suppl/DC1).
An ACR of ≥30 mg/g was detected in 4.77% of subjects. In particular, ACR was moderate (ACR 30–299 mg/g, formerly defined as microalbuminuria) in 84.3% of albuminuric persons, with the remaining 15.7% having severe albuminuria (ACR ≥300 mg/g, formerly defined as macroalbuminuria).
Table 3 provides estimates of the prevalence of subjects at cardio-renal risk based on the combined measure of eGFR and albuminuria level. Very few persons can be considered at high or very high risk considering the concomitant presence of reduced eGFR and high albuminuria. Specifically, among subjects with eGFR <60 mL/min/1.73 m, albuminuria was present in 23.7%, that is 17.0% with moderate and 6.7% with severe albuminuria. The prevalence of moderate and severe albuminuria in individuals with eGFR <60 was, however, substantially higher than that found in the whole group (that is, with and without low eGFR) of hypertensive (5.7 and 1.3%, for moderate and severe albuminuria, respectively) and diabetic subjects (10.6 and 3.1%, respectively).
In the whole sample, hypertension was prevalent in men and women (56.4 and 43.5%, respectively) and the same held true for overweight (48.4 and 33.2%), obesity (25.6 and 27.2%), diabetes (14.5 and 9.0%) and smoking (21.2 and 18.5%), whereas a positive history of CV disease was relatively less frequent (8.5 and 6.3%). Table 1 compares CV risk profile in survey participants with and without CKD. When compared with non-CKD subjects, men and women with CKD had higher fasting glucose, triglycerides, systolic BP, BMI, waist circumference and waist–hip ratio, while HDL cholesterol was lower. CKD was also associated with higher prevalence of hypertension, diabetes, obesity, anaemia, CV disease and low education level. As persons with CKD were on average 10 years older than non-CKD subjects, we repeated the same analysis after age standardization (Supplementary data, Table SB http://ndt.oxfordjournals.org/content/30/5/806/suppl/DC1). This analysis showed that age attenuated but did not substantially modify the differences in the CV risk profile.
Multivariate regression analysis (Table 4) identified age, hypertension and presence of CV disease as main independent correlates of CKD. These results were in fact consistent when analysing separately low GFR and albuminuria. Diabetes and smoking also associated with CKD, but correlated more strictly with albuminuria than low GFR. Conversely, obesity was an independent correlate of CKD, being associated with low eGFR. Males exclusively correlated with albuminuria. Waist–hip ratio or overweight did not correlate with CKD when replacing obesity in the analysis (data not shown).
Results
CKD Prevalence
In the OEC/HES, 8693 persons out of the planned sample of 9020 underwent interviews and examinations (96.4%). Information on ACR or serum creatinine was lacking in 1141 individuals. Thus, CARHES included 7552 Caucasian subjects (84% of the planned sample). In the sample, 28 persons with eGFR <60 mL/min/1.73 m did not have ACR measured; therefore, the evaluation of distribution of albuminuria by eGFR category was obtained in 7524. The general characteristics of the whole population are reported in Table 1.
Table 2 describes unadjusted prevalence estimates of CKD. Overall, prevalence of CKD increased remarkably across age strata, from 2.7% at age 35–49 years to 17.0% at 70–79 years. Early stages of disease accounted for most of the estimated CKD population, the prevalence of the first two CKD stages (4.16%) being higher than that of CKD Stage G3a–5 (2.89%). In particular, persons with eGFR <45 mL/min/1.73 m (Stage G3b–5) represented only 0.78% of the whole population and the 11% of the CKD population. Prevalence of CKD was similar in North [7.0% (95% CI 6.1–7.9)], Centre [5.6% (95% CI 4.3–7.0)] and South [7.8% (95% CI 6.8–8.8)]. When considering the prevalence rates of single stages of disease by gender, we observed a higher prevalence of early—albuminuric—stages in males, with the difference being not maintained in the more advanced stages of disease, G3a–5. Questionnaire-reported awareness of CKD was poor with 10.0% of person with CKD being aware of their condition; awareness increased to 18.4% in those with eGFR <60 mL/min/1.73 m.
CKD prevalence slightly decreased after age standardization to the resident population (overall: 6.29%, 95% CI 5.74–6.84, CKD Stage G1–2 A2–3: 3.78%, 95% CI 3.36–4.22; CKD Stage G3a–5: 2.50%, 95% CI 2.15–2.85), with men showing higher rates of Stage G1–2 A2–3 (4.2 versus 3.4% in females) and slightly lower rates of Stage G3a–5 (2.1 versus 2.8% in females). We can therefore estimate that, in Italy, there is a total number of 2 180 542 adult persons (age 35–79 years) with CKD (1 075 354 men and 1 105 187 women), most with early disease (60.4%) and older age (69.8%; Supplementary data, Table SA http://ndt.oxfordjournals.org/content/30/5/806/suppl/DC1).
An ACR of ≥30 mg/g was detected in 4.77% of subjects. In particular, ACR was moderate (ACR 30–299 mg/g, formerly defined as microalbuminuria) in 84.3% of albuminuric persons, with the remaining 15.7% having severe albuminuria (ACR ≥300 mg/g, formerly defined as macroalbuminuria).
Table 3 provides estimates of the prevalence of subjects at cardio-renal risk based on the combined measure of eGFR and albuminuria level. Very few persons can be considered at high or very high risk considering the concomitant presence of reduced eGFR and high albuminuria. Specifically, among subjects with eGFR <60 mL/min/1.73 m, albuminuria was present in 23.7%, that is 17.0% with moderate and 6.7% with severe albuminuria. The prevalence of moderate and severe albuminuria in individuals with eGFR <60 was, however, substantially higher than that found in the whole group (that is, with and without low eGFR) of hypertensive (5.7 and 1.3%, for moderate and severe albuminuria, respectively) and diabetic subjects (10.6 and 3.1%, respectively).
CV Risk Profile
In the whole sample, hypertension was prevalent in men and women (56.4 and 43.5%, respectively) and the same held true for overweight (48.4 and 33.2%), obesity (25.6 and 27.2%), diabetes (14.5 and 9.0%) and smoking (21.2 and 18.5%), whereas a positive history of CV disease was relatively less frequent (8.5 and 6.3%). Table 1 compares CV risk profile in survey participants with and without CKD. When compared with non-CKD subjects, men and women with CKD had higher fasting glucose, triglycerides, systolic BP, BMI, waist circumference and waist–hip ratio, while HDL cholesterol was lower. CKD was also associated with higher prevalence of hypertension, diabetes, obesity, anaemia, CV disease and low education level. As persons with CKD were on average 10 years older than non-CKD subjects, we repeated the same analysis after age standardization (Supplementary data, Table SB http://ndt.oxfordjournals.org/content/30/5/806/suppl/DC1). This analysis showed that age attenuated but did not substantially modify the differences in the CV risk profile.
Multivariate regression analysis (Table 4) identified age, hypertension and presence of CV disease as main independent correlates of CKD. These results were in fact consistent when analysing separately low GFR and albuminuria. Diabetes and smoking also associated with CKD, but correlated more strictly with albuminuria than low GFR. Conversely, obesity was an independent correlate of CKD, being associated with low eGFR. Males exclusively correlated with albuminuria. Waist–hip ratio or overweight did not correlate with CKD when replacing obesity in the analysis (data not shown).
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