Evaluation of mean neutrophil volume and immature to total neutrophil ratio as a biomarker for bacterial sepsis in adult patients.

Introduction: Mean neutrophil volume (MNV) and immature to total neutrophil ratio (IT Ratio) has been found to support the detection of sepsis in elderly and neonates. This study aimed to assess the diagnostic significance of MNV and IT ratio in adult sepsis population.

Materials and methods: Sixty-four adult patients presented with suspected bacterial sepsis were included in this study. Relevant cultures and/or pertinent serology tests were performed. Full blood counts were analysed for MNV and IT ratio.

Results: Fifty-one patients out of 64 recruited subjects were confirmed sepsis. Twentyfour patients had confirmed bacterial infection by cultivation and two were positive for leptospiral serology. MNV was very good in distinguishing sepsis from non-sepsis group (AUC = 0.80, 95% confidence interval (CI) = 0.69-0.91, Accuracy = 0.72, Kappa = 0.40) with a cut-off value of 153.5 (sensitivity = 67%, specificity = 92%). There was no significant difference in IT ratio between sepsis and non-sepsis group (p-value > 0.05). MNV was superior over IT ratio (AUC = 0.85, 95%CI = 0.76-0.95, and AUC = 0.70, 95% CI = 0.56-0.85, respectively) in diagnosing bacterial infection. The optimum cut-off value for MNV in bacterial infection was 154.5 (sensitivity = 67%, specificity = 89%) and for IT ratio was 0.035 (sensitivity = 45%, specificity = 67%).

Conclusion: MNV appears to be a very good marker for diagnosing sepsis and bacterial infection. We recommend including MNV into sepsis workup in ED setting, since it can be determined without additional specimen.