Accuracy of plasma interleukin-6 and C-reactive protein as markers of sepsis in preterm neonates with respiratory distress syndrome

Kosmas Sarafidis, Charalampos Agakidis, Elisavet Diamanti, Vasiliki Soubasi-Griva, Vasiliki Tzimouli, Vasiliki Drossou


Aim: To evaluate the diagnostic accuracy of plasma interleukin-6 (IL-6) and serum CRP in detecting blood culture proven sepsis in preterm neonates with respiratory distress syndrome (RDS).

Patients and Methods: 140 preterm neonates, 62 with RDS and 78 without RDS, who developed clinical signs of sepsis were prospectively studied. Plasma IL-6 and serum CRP levels were measured. The ROC curves, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratios (LR) were calculated for IL-6 (> 20 pg/mL and > 80 pg/mL) and CRP (> 10 mg/L).

Results: Positive blood cultures were found in 64 neonates (37 with RDS and 27 without RDS). Neonates with RDS had higher IL-6 (p < 0.0001) as compared to neonates without RDS. The ROC curves showed that in neonates without RDS both markers were accurate in diagnosing sepsis with an AUC of 0,914 and 0,863 for IL-6 and the CRP, respectively. However, in neonates with RDS the AUC was 0,642 for IL-6 and 0,808 for CRP. In addition, the sensitivity, specificity and LR for IL-6 > 20 pg/mL was 0,93, 0,65 and 2,68, respectively, in neonates without RDS, and 0,92, 0,16 and 1,09, respectively, in neonates with RDS. The sensitivity, specificity and LR of CRP > 10mg/L were 0,86, 0,71 and 2,97, respectively, in neonates without RDS and 0,73, 0,68 and 2,28, respectively, in neonates with RDS.

Conclusions: In neonates without RDS both the IL-6 and CRP are equally accurate markers in diagnosing sepsis, whereas in those with RDS the diagnostic value of IL-6 is limited.


Preterms, Respiratory distress syndrome, Sepsis, Sensitivity, Specificity

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