WIP 52 - Nadir Serum Creatinine at Age 1 as a Predictor of Prepubertal Moderate-Severe CKD in Patients with Posterior Urethral Valves

Publication Number: WIP 52.7689

Anfal Marafie, Cleveland Clinic Children's, Cleveland, OH, United States; Katherine Dell, Case Western Reserve University School of Medicine, Cleveland, OH, United States

Background: Posterior urethral valves (PUV) is an important cause of progressive chronic kidney disease (CKD) and kidney failure in children. Patients who have moderate-severe CKD (stage 3 or higher) prior to puberty are at high risk for developing kidney failure during puberty, when renal function decline accelerates. Serum creatinine nadir of < 1 mg/dL at age 1 year for PUV patients has been reported to be a favorable prognostic indicator for progression to kidney failure in previous studies. However, those studies utilized various calculators for estimating glomerular filtration rate (eGFR). The recently-developed U25 formula for eGFR calculation is more accurate when compared to previous eGFR formulas.

Objective: To investigate whether serum creatinine levels at 1 year of age can serve as a predictive biomarker for the development of stage 3 CKD or greater using the U25 eGFR equation by age 6-8 years in PUV patients.

Design/Methods: This study is a retrospective chart review of pediatric PUV patients seen between the years of 1995-2018. IRB approval has been obtained. Data will be extracted from our electronic medical record system. Inclusion criteria included subjects with both a serum creatinine value at age 1-2 years and a value between the ages of 6-8 years. Patients who progressed to kidney transplant or dialysis before age 2 were excluded. Only isotope dilution mass spectrometry (IDMS)-traceable creatinine values were used. eGFR was calculated using the CKiD under 25 (U25) formula. Descriptive statistics will be calculated to summarize the baseline characteristics of the study population. To model the relationship between serum creatinine at age 1 and the development of CKD stage 3 or greater, logistic regression analysis will be performed. Receiver Operating Characteristic (ROC) curve analysis will be utilized to evaluate the predictive ability of serum creatinine in assessing sensitivity and specificity at various thresholds. The area under the curve (AUC) will be calculated to quantify the overall discriminative ability of serum creatinine to predict CKD progression.