Abstract Purpose Neonates admitted to intensive care units are at high risk of hospital-acquired infections. While blood cultures remain the gold standard for sepsis diagnosis, they do not detect infection in every case. Host immune response markers, such as C-reactive protein and procalcitonin, can assist in earlier detection but also have limitations and carry additional costs. We have developed a Neonatal Intensive Care Infection Score (NICIS), which leverages extended complete blood count (CBC+Diff + EIP) parameters, which may require specific analyser configuration or software licensing, to extract additional diagnostic value. Methods We conducted a retrospective cohort study of neonates admitted to the Neonatal Intensive Care Unit at the John Radcliffe Hospital (Oxford, UK) over one year. Eighteen CBC+Diff + EIP parameters were initially considered based on their ability to differentiate culture-positive patients from those without clinical suspicion of infection. NICIS was developed as a weighted score and validated internally using a temporally distinct dataset and externally using a four-year retrospective cohort from Erasmus University Medical Center (Rotterdam, The Netherlands). Results Incorporating eight CBC+Diff + EIP parameters, NICIS values ranged from 0 to 25, with higher scores indicating a greater likelihood of sepsis. NICIS achieved an area under the curve of 0.906 in training, 0.879 in internal validation, and 0.841 in external validation, outperforming C-reactive protein and total white blood cell count in all datasets. Conclusions NICIS provides an interpretable tool for sepsis detection using routinely collected CBC+Diff + EIP data without additional sampling. Its performance across internal and external cohorts suggests sufficient diagnostic accuracy, although prospective studies are warranted to further assess generalisability and clinical utility.
Hyde et al. (2026) studied this question.