Delta Neutrophil Index for Predicting Mortality in Critically Ill Surgical Patients with Acinetobacter baumannii Pneumonia

ABSTRACT

PURPOSE: This retrospective study evaluated the clinical utility of the delta neutrophil index (DNI) as a predictor of mortality in critically ill surgical patients with Acinetobacter baumannii (AB) pneumonia. METHODS: The medical records of 104 surgical patients with AB pneumonia treated from March 2011 to October 2014 were reviewed and analyzed. RESULTS: The mean patient age was 60.8±18.8 years, and the mean Acute Physiology and Chronic Health Evaluation II score was 15.8±5.3. At the time of culture, 16 patients (15.4%) had renal failure, and the median DNI was 2.7% (0∼39.4%). Twenty-four patients (23.1%) died from infection during intensive care unit admission. Bivariate analysis indicated that several factors were associated with mortality, namely age, occurrence of shock, renal failure, low platelet count and elevated DNI at the time of culture. Logistic regression analysis revealed that elevated DNI (odds ratio [OR], 1.136; 95% confidence interval [CI], 1.001∼1.288), acute renal failure (OR, 3.811; 95% CI, 1.025∼14.176) and decreased platelet count (OR, 0.994; 95% CI, 0.989∼1.000) at the time of culture are associated with mortality. When a receiver-operating characteristics curve was constructed to determine the optimal cut-off value to predict mortality within seven days of the bacterial culture, the area under the curve was 0.839 (95% CI, 0.694∼0.985) and the cut-off DNI value was 6.85%. CONCLUSION: DNI may be an effective predictor of mortality in critically ill surgical patients with AB pneumonia.