Discussion
death, hypoxia-ischemia, NDI, brain injury, HIE, erythropoietin-associated
SECONDARY
In this ancillary study of a contemporary multicenter randomized, placebo-controlled trial in newborns born at full term with HIE receiving TH, we found that, contrary to our first hypothesis, treatment with erythropoietin was not associated with changes in 18 inflammatory mediators at baseline, day 2, or day 4. This finding was surprising given that erythropoietin-associated neuroprotection demonstrated in preclinical studies has been partly attributed to anti-inflammatory mechanisms in animal modelsOur second hypothesis, that a combination of 1 or more brain-specific proteins or cytokines would be associated with the presence and severity of brain injury, was confirmed. We demonstrated an association of several circulating biomarkers with death or NDI at 2 years of age across all biomarker categories (pro-inflammatory, anti-inflammatory, brain-specific proteins, and other growth factors) and at all time points. We then selected putative plasma biomarkers of brain injury from an array of candidate inflammatory cytokines, brain-specific proteins, and growth factors into a final curated model. After adjusting for multiple comparisons, we identified 6 plasma biomarkers (C5a, IL-6, and NSE at baseline; IL-8, tau, and UCHL1 at day 4) that significantly improved estimation of death or NDI at 2 years compared with clinical data alone. However, the improvement was only modest, increasing the AUC from 0.73 (95% CI, 0.70-0.75) to 0.79 (95% CI, 0.77-0.81, Our findings confirm prior, largely single-center, observational studies suggesting that circulating inflammatory cytokines may provide insights into the propagation of secondary brain injury after hypoxia-ischemia leading to NDI.Our curated model included 3 pro-inflammatory proteins: IL-6, IL-8, and C5a. Our findings support early measurement (ie, in the first 24 hours of life) of pro-inflammatory cytokine IL-6, consistent with prior studies that have evaluated comparative predictive abilities of serial IL-6 measurements.Our curated set of biomarkers also included the brain specific proteins UCHL1,To address our third hypothesis, that adding selected biomarkers to clinically available information would improve projection of 2-year neurodevelopmental outcomes, we assessed the added value of biomarker determinations in combination with baseline and clinical characteristics. While we chose factors that have been previously reported as indicators of HIE severity and risk for adverse outcomes,To our knowledge, this is the largest multicenter study evaluating biomarker data from a contemporary cohort of cooled neonates with HIE. Strengths of our study include biomarker and neurodevelopmental outcome assessments performed within the rigor of a multicenter randomized clinical trial. Our data-driven analytical approach and adjustments for multiple comparisons allowed us to screen a robust array of candidate biomarkers and select the most promising biomarkers to develop a cumulative model.