Assessing the Predictive Value of the Neutrophil-to-Lymphocyte Ratio for Post-Thrombotic Syndrome following Iliofemoral Deep Venous Thrombosis

Abstract

Post-thrombotic syndrome (PTS) is a common complication of deep vein thrombosis (DVT) that occurs in 20-50% of patients and results in a decreased quality of life. Even with the progressive identification of PTS risk factors, clinically useful predictors of PTS continue to be limited, unobjective, and ill-defined. The neutrophil-to-lymphocyte ratio (NLR) is an emerging prognostic biomarker used in a variety of diseases that reflects acute systemic inflammation. This pilot study aimed to evaluate the utility of the NLR at the time of iliofemoral DVT diagnosis in predicting PTS incidence in patients. A retrospective chart review was performed on patients identified with iliofemoral DVT at the University of Maryland Medical Center between 2020 and 2022. Patients with at least one follow-up visit between 3 to 6 months after initial DVT diagnosis were included. Diagnosis of PTS was determined based on Villalta Score. The Youden index with receiver operating characteristic (ROC) curve analysis was used to determine the NLR cutoff value that was predictive of PTS. A multivariable logistic regression model was then performed to assess the utility of this NLR cutoff value and other common clinical markers in predicting the presence of PTS symptoms. 418 patients with positive iliofemoral DVT venous duplex ultrasounds were screened for eligibility. 118 patients were eligible with a mean age of 53.18 ± 15.45 years. A total of 43 patients (36.44%) were found to have PTS. A NLR cutoff of 7.71 was determined with an area under the ROC curve (AUC) of 0.63 (p=0.046). When the NLR was assessed jointly with other clinical markers at the time of DVT diagnosis, NLR was a statistically significant positive predictor, measured using odds ratio (OR, 1.83; 95% CI, 1.20-2.78; p=0.005). Our study found that when stratified by a determined cutoff value, the NLR at the time of DVT diagnosis was significantly associated with the development of PTS in patients with iliofemoral DVT. This result is consistent with one prior research finding yet is novel in its specificity for iliofemoral DVTs and its acute lab collection for NLR calculation. The NLR should be further investigated as a potential inexpensive prognostic tool to aid in the improvement of treatment and prophylactic strategies for PTS.