Influence of serum bilirubin levels on the occurrence and course of neonatal sepsis in preterm infants younger than 36 gestational age weeks / Influência dos níveis séricos de bilirrubina sobre a ocorrência e a evolução da sepse neonatal em recém-nascidos pré-termo com idade gestacional menor que 36 semanas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

INTRODUCTION: several components of the antioxidative defenses are deficient in the newborn. Bilirubin is a potent antioxidant and can counterbalance the deficiency of those components. This antioxidant action is potencialized by biliverdin reductase. The present study aimed at identifying the protective effect of bilirubin on neonatal sepsis in premature babies. METHODS: cohort study, carried out in two neonatal intensive care unities. Newborns younger than 36 gestational age weeks and birth weight between 750 and 1750g were included in the study. Bilirubin and protein carbonyl measurements were performed: a) at birth, b) at day three, c) at day seven, d) at day fourteen. Student t test was used for mean comparisons. Bilirubin measurements at day three were used to build a ROC curve. The inflection point of this curve separated the high bilirubin from the low bilirubin group. Relative risk and 95% confidence interval were determined. Chi-square test was applied for categorical variables and the significance level was set at α=5%. RESULTS: fifty-three patients were included in the study. Twenty-four patients (45.3%) had proven sepsis, twelve (22.6%) had clinical sepsis, totaling 36 (67.9%) patients with all forms of sepsis and 21 (39.6%) patients with severe sepsis. Comparisons between bilirubin values in patients with each form of sepsis and patients without sepsis showed significant differences in most of the situations. There was no statistically significant difference in birth measures in all forms of sepsis as well as in day 14 measurements for severe sepsis. Very good statistical results were found on day three comparisons between proven sepsis and no sepsis patients p=0.0009. The ROC curve inflection point, with bilirubin level at 9.8 mg%, identified an exposed and a non-exposed group. Comparisons regarding the presence of sepsis between groups showed a statistically significant difference, considering each of the analyzed sepsis forms. For proven sepsis RR=0.39 (95%CI 0.22-0.71) p=0.0008. Bilirubin curves showed a significant difference between the areas of the two curves, with patients without sepsis displaying a larger area. The correlation between bilirubin maximum values and protein carbonyl maximum values was inverse and significant (p=0.016). The difference regarding protein carbonyl values between patients with each form of sepsis and patients without sepsis did not reach statistical significance. These results show a statistical significant relation between higher bilirubin levels and a lower incidence and severity of neonatal sepsis and a significant correlation between bilirubin and protein carbonyl. CONCLUSION: higher bilirubin levels protect premature babies from the occurrence and severity of sepsis due to its antioxidative properties.

ASSUNTO(S)

antioxidantes sepse premature infant estresse oxidativo prematuro estudos de coortes. newborn infant bilirubin sepsis bilirrubina antioxidants cohort studies. oxidative stress recém-nascido

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