What are the cut-off levels for IL-6 and CRP in neonatal sepsis?

Neonatal sepsis, characterized by systemic signs of infection in the first month of life, remains an important clinical syndrome. Despite advances in neonatology, it has high rates of mortality and morbidity. The combine or alone usage of interleukin-6 (IL-6) and C-reactive protein (CRP) has recently been proven to be useful in the early diagnosis of sepsis in newborns. The study included 282 patients; there were 232 in Group I (170 proven and 62 clinical sepsis) and 50 in Group II (control group). The optimum cut-off value in the diagnosis of neonatal sepsis was found to be 24.65 pg/ml for IL-6 and 4.82 mg/l for CRP. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of this IL-6 cut-off for neonatal sepsis were 72, 84, 95, and 42%, respectively. Sensitivity, specificity, PPV, and NPV of the CRP cut-off for neonatal sepsis were 67, 97, 99, and 39%, respectively. The combination of IL-6 (>24.65 pg/ml) and CRP (>4.82 mg/l) in the diagnosis of neonatal sepsis gave sensitivity, specificity, PPV, and NPV of 53, 100, 100, and 33%, respectively. To our knowledge, this is the largest reported study seeking to determine cut-off levels for IL-6 and CRP in the diagnosis of neonatal sepsis. In conclusion, we think that it is useful to evaluate IL-6 and CRP, in combination, for the early diagnosis of neonatal sepsis.