Background: Data on the epidemiology of chronic kidney disease (CKD), which is a serious health problem and refers to a condition related to irreversible kidney damage that further progress to end-stage renal disease in children, are insufficient and data that are available were based on hospital records. The aim of this nationwide, population-based field study was to determine the prevalence of CKD in children in Turkey and to evaluate the association between CKD and possible risk factors such as obesity and hypertension.
Methods: The study was the paediatric stratum (3622 children aged 5-18 years) of the previously published population-based survey of Chronic REnal Disease In Turkey (CREDIT study). Medical data were collected through home visits and interviews between November 2007 and July 2008; height, weight and blood pressure were also measured. Serum creatinine, total cholesterol, uric acid and complete blood count were determined from 12-h fasting blood samples, and spot urine tests were performed for subjects who gave consent to laboratory evaluation.
Results: Following adjustment according to gender, residence, age groups and geographical regions, the prevalence of children with estimated glomerular filtration rate (eGFR) <75 mL/min/1.73 m(2) was 0.94 [95% confidence interval (CI): 0.63-1.35], and the prevalence of children with CKD Stages 3-5 [National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (K/DOQI)] was 2600 (95% CI 1100-5100) per million age related population. The mean eGFR was found to increase with age; the ratios of children with eGFR <90 and <75 mL/min/1.73 m(2) were higher in younger age groups. The frequencies of overweight and obese children were 9.3 and 8.9%, respectively, and the mean eGFR was lower in patients with higher body mass index. The prevalence of hypertension and hypercholesterolaemia was 6.1 and 5.8%, respectively; the mean eGFR was lower in children with hypercholesterolaemia.
Conclusions: This is the first population-based CKD study performed in children aged 5-18 years. The prevalence of CKD in our study was 25-100 times greater than that found in previous hospital-based studies. Our data suggest that approaches focusing on patients in tertiary centres are likely to lead to patients being missed at early stages of CKD and that a vast majority of these children will never develop symptomatic CKD during childhood.