Is Low Birth Weight an Antecedent of CKD in Later Life? A Systematic Review of Observational Studies

Background: There has been considerable interest in the hypothesis that low birth weight may be a marker of impaired nephrogenesis and that this is causally related to chronic kidney disease (CKD). Study Design: Systematic review and meta-analysis of observational studies. Setting & Population: Studies of the relationship between birth weight and CKD published before February 1, 2008, were identified by using electronic searches. Selection Criteria: All studies that had collected data for birth weight and kidney function at greater than 12 months of age were eligible for inclusion, except for studies of extremely low-birth-weight infants, very premature infants, or toxic exposure in utero. Study Factor: Birth weight. Outcomes: CKD defined as albuminuria, low estimated glomerular filtration rate (<60 mL/min/1.73 m(2) or < 10th centile for age/sex), or end-stage renal disease. Results: We analyzed 31 relevant cohort or case-control studies with data for 49,376 individuals and data for 2,183,317 individuals from a single record-linkage study. Overall, 16 studies reported a significant association between low birth weight and risk of CKD and 16 observed a null result. The combination of weighted estimates from the 18 studies for which risk estimates were available (n = 46,249 plus 2,183,317 from the record linkage study) gave an overall odds ratio (OR) of 1.73 (95% confidence interval [CI], 1.44 to 2.08). Combined ORs were consistent in magnitude and direction for risks of albuminuria (OR, 1.81; 95% CI, 1.19 to 2.77), end-stage renal disease (OR, 1.58; 95% Cl, 1.33 to 1.88), or low estimated glomerular filtration rate (OR, 1.79; 95% Cl, 1.31 to 2.45). Limitations: A reliance on published estimates and estimates provided on request rather than individual patient data and the possibility of reporting bias. Conclusions: Existing data indicate that low birth weight is associated with subsequent risk of CKD, although there is scope for additional well-designed population-based studies with accurate assessment of birth weight and kidney function and consideration of important confounders, including maternal and socioeconomic factors. Am J Kidney Dis 54:248-261. (C) 2009 by the National Kidney Foundation, Inc.