Patients and Study Design

The retrospective cohort study was in accordance with the principles of the 1964 Declaration of Helsinki and its later amendments. Written informed consent was obtained from all patients before participating in this study. Children and adolescents aged 3 to 18 years with CKD from the pediatric nephrology outpatient clinics in Kaohsiung Chang Gung Memorial Hospital, Taiwan, were recruited between December 2016 and October 2018. CKD was defined and staged according to the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (K/DOQI) (11). Using the bedside CKiD equation, kidney function was expressed as estimated glomerular filtration rate (eGFR) based on height and serum creatinine concentration (12).

A patient was excluded from this study if she/he (a) had eGFR <15 ml min⁻¹ 1.73 m⁻², (b) was undergoing dialysis, (c) was a kidney transplant patient, (d) was currently pregnant, (e) had a history of congenital heart disease, (f) lost to follow-up, or (g) was unable to cooperate during the examinations.

The analysis was limited to children and adolescents with baseline eGFR >15 ml min⁻¹ 1.73 m⁻². The measurements of renal and cardiovascular parameters are described in the following sections.