Predictive value of serum interleukin-6 for neonatal encephalopathy outcomes.

Background: Serum interleukin-6 (IL-6) may predict adverse outcomes of neonatal encephalopathy (NE); however, limited data regarding the predictive utility of IL-6 during neurodevelopmental follow-up are available. We aimed to determine the utility of IL-6 for predicting adverse outcomes at 18 to 22 months of age.

Methods: Eighty-seven patients with NE who received therapeutic hypothermia were enrolled in this study. Serial serum IL-6 levels during the first 3 postnatal days were collected. Patients were classified into three groups: 1) death, 2) survival with moderate to severe neurodevelopmental disability (NDD) at 18-22 months of age, and 3) survival without NDD (favorable outcome). The predictive ability of IL-6 was determined by the area under the receiver-operating characteristic curve (AUC).

Results: Serial IL-6 data of 80 patients with NE were available and showed peak levels on postnatal day 1; these levels gradually decreased toward day 3. By 18-22 months of age, 13 and 17 patients died and experienced moderate to severe NDD without death, respectively. Fifty patients experienced favorable outcomes. Higher IL-6 levels on day 1 predicted the composite adverse outcome (including death and survival with NDD; n = 30; AUC, 0.648). Higher IL-6 levels on day 1 predicted death (n = 13; AUC, 0.799), whereas higher IL-6 levels on day 1 predicted survival with NDD (n = 17; AUC, 0.536).

Conclusions: The AUC of IL-6 that predicted survival with NDD was lower than the AUC of IL-6 that predicted death; therefore, IL-6 may have insufficient utility for predicting NDD without death.