AbstractWe performed a meta-analysis to seek evidence for the usefulness of the delta neutrophil index (DNI) as a prognostic blood biomarker for mortality in the early stage of sepsis in adults. A literature search was performed using criteria set forth in a predefined protocol. Studies of adults with sepsis that provided a DNI measurement and that had mortality as the outcome, were included. Review articles, editorials, and non-human studies were excluded. The methodological quality of identified studies was assessed independently by two authors using the Quality in Prognosis Studies (QUIPS) tool. A total of 1,822 patients from eleven studies were ultimately included. Standardized mean differences between non-survivors and survivors were compared. An elevated DNI was associated with mortality in patients with sepsis (standardized mean difference [SMD] 1.22; 95% confidence interval 0.73–1.71; I² = 91%). After excluding two studies—one that included paediatric patients and one with a disproportionately low mortality rate—heterogeneity was minimized (SMD 0.74, 95% confidence interval 0.53–0.94; I² = 43%). Overall, the findings suggest that high DNI values are associated with mortality in septic patients.