Caffeine and kidney function at two years in former extremely low gestational age neonates

Background: Extremely low gestational age neonates (ELGANs) are at risk for chronic kidney disease. The long-term kidney effects of neonatal caffeine are unknown. We hypothesize that prolonged caffeine exposure will improve kidney function at 22–26 months. Methods: Secondary analysis of the Preterm Erythropoietin Neuroprotection Trial of neonates <28 weeks’ gestation. Participants included if any kidney outcomes were collected at 22–26 months corrected age. Exposure was post-menstrual age of caffeine discontinuation. Primary outcomes: ‘reduced eGFR’ <90 ml/min/1.73 m², ‘albuminuria’ (>30 mg albumin/g creatinine), or ‘elevated blood pressure’ (BP) >95th %tile. A general estimating equation logistic regression model stratified by bronchopulmonary dysplasia (BPD) status was used. Results: 598 participants had at least one kidney metric at follow up. Within the whole cohort, postmenstrual age of caffeine discontinuation was not associated with any abnormal measures of kidney function at 2 years. In the stratified analysis, for each additional week of caffeine, the no BPD group had a 21% decreased adjusted odds of eGFR <90 ml/min/1.73m² (aOR 0.78; CI 0.62–0.99) and the BPD group had a 15% increased adjusted odds of elevated BP (aOR 1.15; CI: 1.05–1.25). Conclusions: Longer caffeine exposure during the neonatal period is associated with differential kidney outcomes at 22–26 months dependent on BPD status. Impact: In participants born <28 weeks’ gestation, discontinuation of caffeine at a later post menstrual age was not associated with abnormal kidney outcomes at 22–26 months corrected age.When assessed at 2 years of age, later discontinuation of caffeine in children born <28 weeks’ gestation was associated with a greater risk of reduced eGFR in those without a history of BPD and an increased odds of hypertension in those with a history of BPD.More work is necessary to understand the long-term impact of caffeine on the developing kidney.