Design and methods of the Chronic Kidney Disease in Children (CKiD) prospective cohort study.

An estimated 650,000 Americans will have ESRD by 2010. Young adults with kidney failure often develop progressive chronic kidney disease (CKD) in childhood and adolescence. The Chronic Kidney Disease in Children (CKiD) prospective cohort study of 540 children aged 1 to 16 yr and have estimated GFR between 30 and 75 ml/min per 1.73 m2 was established to identify novel risk factors for CKD progression; the impact of kidney function decline on growth, cognition, and behavior; and the evolution of cardiovascular disease risk factors. Annually, a physical examination documenting height, weight, Tanner stage, and standardized BP is conducted, and cognitive function, quality of life, nutritional, and behavioral questionnaires are completed by the parent or the child. Samples of serum, plasma, urine, hair, and fingernail clippings are stored in biosamples and genetics repositories. GFR is measured annually for 2 yr, then every other year using iohexol, HPLC creatinine, and cystatin C. Using age, gender, and serial measurements of Tanner stage, height, and creatinine, compared with iohexol GFR, a formula to estimate GFR that will improve on traditional pediatric GFR estimating equations when applied longitudinally is expected to be developed. Every other year, echocardiography and ambulatory BP monitoring will assess risk for cardiovascular disease. The primary outcome is the rate of decline of GFR. The CKiD study will be the largest North American multicenter study of pediatric CKD.