Association of low birth weight and prematurity with clinical outcomes of childhood nephrotic syndrome: a prospective cohort study

Abstract

BackgroundLow birth weight (LBW)/prematurity have been proposed as risk factors for the development of kidney disease in adulthood. Whether there is an association between LBW/prematurity and poor renal outcomes in childhood onset nephrotic syndrome remains unknown.MethodsChildren with nephrotic syndrome diagnosed between 1 and 18\xa0years of age were followed prospectively from 1996 to 2016 at The Hospital for Sick Children (N\u2009=\u2009377). LBW/prematurity was defined as birth weight <\u20092500\xa0g or gestational age <\u200936\xa0weeks. Normal birth weight (NBW) was defined as birth weight ≥\u20092500\xa0g. Measures evaluating clinical course of nephrotic syndrome include initial steroid-resistant nephrotic syndrome (SRNS), time to first relapse, and frequently relapsing nephrotic syndrome. Kaplan-Meier survival analysis, logistic regression, and Cox proportional hazards regression were used to determine the association of LBW/prematurity with clinical outcomes.ResultsMedian birth weights in LBW/premature (n\u2009=\u200946) and NBW (n\u2009=\u2009331) children were 2098\xa0g (interquartile range [IQR] 1700–2325\xa0g) and 3317\xa0g (IQR 2977–3685\xa0g), respectively. Odds of having SRNS were 3.78 (95% confidence interval [CI] 1.28–11.21) times higher among LBW/premature children than NBW children. An 8% decrease in odds of developing SRNS was observed for every 100\xa0g increase in birth weight (adjusted odds ratio [OR] 0.92; 95% CI 0.86–0.98). Median time to first relapse did not differ (hazard ratio [HR] 0.89; 95% CI 0.53–1.16).ConclusionsLBW/premature children were more likely to develop SRNS but did not have a difference in time to first relapse with NBW children. Understanding the impact and mechanism of birth weight and steroid-resistant disease needs further study.