Abstract 1581 Poster Session II, Sunday, 5/2 (poster 117)

Objective. To examine whether the determination of IL-8 and CRP in neonates with suspected NBI is safe, feasible, and cost-effective in reducing antibiotic therapy. Methods. Between April 1996 and May 1997, IL-8 was measured 260 times along with blood cultures, CRP and Immature-to-Total-Neutrophil-Ratio (IT-ratio) for suspected NBI in term and preterm neonates. All infants were retrospectively analyzed for NBI. Sensitivity, specificity, positive and negative predictive values, and 95% confidence intervals were calculated for IL-8, CRP and IT-ratio. Receiver-operating characteristic (ROC)-curves were analyzed to determine optimal thresholds. Between June 1997 and June 1998, IL-8 was measured 215 times in newborn infants with suspected NBI and the decision to start antibiotic therapy was based on increased IL-8 and/or CRP values. Patient outcome was monitored, a cost-effectiveness analysis was performed and sensitivity, specificity, ROC-curves were reevaluated. The diagnosis of 'culture-proven NBI' was based on clinical signs and positive blood or cerebrospinal fluid cultures, that of 'clinical NBI' on clinical signs and a CRP > 10mg/l 12-60 hours after initial evaluation. Results. At the first suspicion of NBI, the combination of IL-8 ≥53pg/ml and/or CRP ≥ 10 mg/l detected culture-proven NBI with 96% (100%) sensitivity in the first (second) study period. The combined culture-proven and clinical NBI were detected with 93% (100%) sensitivity and 80% (83%) specificity. Using IL-8 reduced 'unnecessary' antibiotic therapy for suspected NBI by 73% and was cost-effective. No NBI related adverse outcome was observed in the second study period despite delaying antibiotic therapy until IL-8 and CRP were available. Conclusions. The combination of IL-8 and CRP is a reliable and early test for the diagnosis of NBI in neonates. It allows to restrict antibiotic therapy to truly infected infants, and to safely reduce 'unnecessary' antibiotic therapy and costs.