Combined delta neutrophil index and red blood cell distribution width as a new biomarker to predict endometriosis

Objective: The aim of this study was to evaluate the use of delta neutrophil index (DNI) in predicting endometriosis.

Material and methods: A retrospective, case-control study was performed in a tertiary care center. DNI, red cell distribution width (RDW), and other blood parameters obtained from complete blood counts of 267 patients, consisting of 122 (45.7%) endometriosis patients with proven pathology reports of stages 3-4, and a control group of 145 women who underwent laparoscopy for simple ovarian cyst and/or diagnostic purposes and had normal histopathology, were compared. Receiver operating characteristic and logistic regression analyses were performed.

Results: DNI and RDW were significantly higher in endometriosis patients than in the control group (p=0.034 and p=0.003, respectively). Other parameters obtained from complete blood counts (leukocyte, neutrophil, lymphocyte, monocytes, and platelet counts and neutrophil-to-lymphocyte ratio), did not differ (p>0.05). For DNI, at a cut-off value of 0.025, area under the curve (AUC) was 0.572 and it was statistically significant [p=0.042; 95% confidence interval (CI): 0.503-0.642, sensitivity: 45.9%, specificity: 67.6%, Youden’s index: 0.135]. For RDW, AUC: 0.601 for cut-off value of 13.65 was statistically significant (p=0.004, 95% CI: 0.553-0.669, sensitivity: 50.8%, specificity: 67.6%, Youden’s index: 0.184). The logistic regression model established with the combined marker obtained by multiplying the DNI and RDW was statistically significant (p<0.001, Nagelkerke R2=0.72, 95% CI: 2.58-47.26, B: 2.40, negative predictive value: 78.6%, positive predictive value: 37.7%).

Conclusion: DNI, a new inflammatory marker, and RDW, known to be associated with inflammation, may be useful minimally invasive biomarkers of endometriosis.