High Prevalence and Limited Perinatal Prediction of Kidney Dysfunction in Adolescents Born Extremely Preterm

Extremely preterm birth (< 28 weeks' gestation) increases chronic kidney disease (CKD) risk. However, among those born extremely preterm, the prevalence of abnormal kidney health during adolescence and its perinatal predictors remain poorly defined.

Adolescents from the Extremely Low Gestational Age Newborn -Environmental influences on Child Health Outcomes (ELGAN-ECHO) cohort (14 US hospitals) were assessed for abnormal kidney health defined as ≥ 1 indicator-chronic kidney disease in children (CKiD) U25 estimated glomerular filtration rate (eGFR) < 90 ml/min per 1.73 m², blood pressure (BP) ≥ 120/80 mm Hg, or microalbuminuria > 30 mg/g.Five feature selection methods screened perinatal covariate predictors using a 60 to 40 training-test split. Multiple imputation addressed missing data in sensitivity analyses. Area under the curve (AUC) was the primary performance metric.

Of the 675 adolescents (mean age 18 years), 354 (52%) had a classifiable kidney health status, as follows: 188 with all 3 measurements and 166 with partial measurements showing ≥ 1 abnormality. The prevalence of abnormal kidney health was 66% among complete cases (125/188) and 82% among all determinate cases (291/354). In the full cohort, prevalence ranged from 43% to 91% (bounding estimates accounting for missing data). Individual measurements revealed 30.5% with reduced eGFR, 42% with elevated BP, and 9% with microalbuminuria. Across all methods, perinatal covariates achieved random test-set discrimination (AUC: 0.48-0.55) for abnormal kidney health prediction, compared with training set AUCs of 0.66-0.72.

Abnormal kidney health is highly prevalent after extremely preterm birth, underscoring the importance of protocolized longitudinal kidney health surveillance throughout childhood to enable early identification of CKD and elevated BP in children born extremely preterm. The perinatal factors we examined did not meaningfully predict kidney health abnormalities and variable importance did not translate to individual-level prediction in this cohort.