Delta neutrophil index (DNI) as a novel diagnostic and prognostic marker of infection: a systematic review and meta-analysis

Objective: Delta neutrophil index (DNI) representing the number of immature granulocytes is an emerging marker used in diagnosis of infections and prediction of mortality in infected patients. The present study evaluated the diagnostic accuracy of DNI as a predictive and prognostic factor in infected patients. Methods: We performed a PubMed search on January 1st, 2017 and identified studies that evaluated DNI as either a predictive or prognostic factor in infected patients. Studies with appropriate information to construct 2 × 2 contingency tables were extracted. We calculated pooled sensitivity and specificity. Meta-analysis of the multivariate logistic regression data set was performed to assess whether DNI functions as an independent factor. Results: Overall, 12 articles fulfilled the inclusion criteria and a total of 499 cases and 9549 controls were examined. As a predictive factor of infection, DNI’s pooled sensitivity was 0.67 (95% CI 0.62–0.71, I² = 86.0%) and pooled specificity was 0.94 (95% CI 0.94–0.95, I² = 92.8%). Area under the receiver operating characteristics (ROC) curve was 0.89. As a prognostic factor for death in infected patients, DNI’s pooled sensitivity was 0.70 (95% CI 0.56–0.81, I² = 0.0%) and pooled specificity was 0.78 (95% CI 0.73–0.83, I² = 26.6%). Area under the ROC curve was 0.84. Meta-analysis of the multivariate logistic regression data set showed insignificant results. Conclusions: DNI is a potentially useful diagnostic tool and predicts mortality among infected patients and should be more widely used in the clinical practice.