High level of neutrophil to lymphocyte ratio increases the risk of deep venous thrombosis in intensive care unit patients after oral cancer surgery: a retrospective study.

Background: The incidence of deep venous thrombosis (DVT) is higher in surgical patients, but there have been few studies on the risk factors of DVT in intensive care unit (ICU) patients after oral cancer surgery, particularly in relation to the inflammatory and nutritional scores, and intervene with these risk factors early may decrease the occurrence of DVT. Methods: We performed a retrospective study of adult patients who were admitted to ICU after undergoing radical resection of oral cancer and performed ultrasound detection for DVT within 1 week after surgery from April 2019 to July 2021. DVT was diagnosed by venous ultrasonography of the lower extremities. Preoperative inflammatory and nutritional scores, including neutrophil to lymphocyte ratio (NLR), plate to lymphocyte ratio (PLR), prognostic nutritional index (PNI) were retrospectively calculated according to test results before surgery. Clinical characteristics, including the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Caprini Risk Score (CRS), Charlson comorbidity index, anticoagulation therapy, and mechanical ventilation time (MVT) after admitted to ICU were obtained. The risk factors affecting DVT occurrence were analyzed by logistic regression, and the receiver operating characteristic (ROC) curve was used to analyze the value of the relevant indicators in evaluating DVT. Results: Among the 128 patients, 43 patients (33.6%) developed DVT. Compared with the non-DVT group, the preoperative glucose (GLU), postoperative D-dimer (P<0.05), and postoperative NLR (P<0.001) were higher in the DVT group than in the non-DVT group. In multivariate logistic analysis, NLR (P=0.001), postoperative D-dimer >5.57 µg/mL (P=0.002), GLU >5.15 mmol/L (P=0.025) was associated with DVT, and the areas under the curve (AUCs) of NLR in predicting DVT was 0.729. We also found that the DVT group had longer MVT and length of stay (LOS) than the non-DVT group, and correlation analysis indicated that NLR level was positively related with MVT (r=0.36; P<0.0001) and LOS (r=0.452; P<0.0001). Conclusions: A high level of NLR, indicative of a poor immunity and nutrition status, increases the risk of DVT in patients after oral cancer surgery, and improvement of immunity and nutrition status may help decrease the occurrence of postoperative DVT.