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

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

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.

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%).

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