Risk Factors for Venous Thromboembolism Following Oral and Maxillofacial Cancer Surgery With Free Flap Reconstruction.

[BACKGROUND] Patients with oral maxillofacial cancer who undergo tumor resection and simultaneous free flap reconstruction face an increased risk of developing postoperative venous thromboembolism (VTE). However, the precise incidence, specific risk factors, and optimal diagnostic parameters in this surgical context remain unclear.

[PURPOSE] The purpose pf the study was to estimate the incidence of VTE and associated risk factors, as well as to measure the association between D-dimer (DD) levels and VTE among patients undergoing tumor resection and simultaneous free flap reconstruction.

[STUDY DESIGN, SETTING, SAMPLE] A retrospective cohort study was conducted at Peking Union Medical College Hospital from September 2023 to August 2025. The sample included patients with oral maxillofacial cancer undergoing tumor resection and free flap reconstruction. Exclusion criteria were osteoradionecrosis, medication-related osteonecrosis, recurrent tumor, or prior VTE.

[PREDICTOR VARIABLE] The primary predictor variable was the plasma DD level, measured in fibrinogen equivalent units (μg/mL). DD levels were assessed preoperatively and on postoperative days 0, 1, and 2. For the primary multivariable analyses, the DD level on the day of surgery (POD 0) was analyzed as a continuous variable.

[MAIN OUTCOME VARIABLE] The main outcome variable was postoperative VTE confirmed through imaging examinations, encompassing deep vein thrombosis (DVT), and pulmonary embolism (PE).

[COVARIATES] The covariates were a set of risk factors associated with VTE, including demographic, clinicopathologic, and surgical characteristics of the subjects.

[ANALYSES] Demographic and clinical characteristics were compared using unpaired t tests, χ tests, Mann-Whitney U tests, Kruskal-Wallis tests, or Spearman's correlation as appropriate. Receiver operating characteristic analyses evaluated area under the curve (AUC) for D-dimer concentration to predict postoperative VTE. Univariate and multivariable logistic regression analyses were performed to identify risk factors.

[RESULTS] The sample was composed of 90 subjects with a mean age of 60.69 ± 12.93 years, 32 (35.6%) were female, and 43 (47.8%) subjects developed VTE. The majority of subjects (32 of 43, 74.4%) were asymptomatic. Multivariable logistic regression revealed that variables including female (adjusted odds ratio [aOR] = 2.91, 95% CI: 1.01-8.40), higher Caprini VTE risk score (aOR = 1.90 per 1-point increase, 95% CI: 1.20-3.99), and higher DD levels on the day of surgery (aOR = 1.72 per 1μg/mL increase, 95% CI:1.16-2.54) were associated with VTE development. Receiver operating characteristic analysis revealed DD cutoffs of 1.74 μg/mL (sensitivity 65.1%, specificity 80.9%, positive predictive value 75.7%, and negative predictive value 71.7%) on the day of surgery and 2.34 μg/mL (sensitivity 79.1%, specificity 83.0%, positive predictive value 79.1%, and negative predictive value 80.9%) on postoperative day 1 for predicting VTE.

[CONCLUSIONS AND RELEVANCE] The postoperative VTE incidence following radical resection and reconstruction for oral maxillofacial cancer is substantial (47.8%), and most cases were asymptomatic. Enhanced postoperative monitoring is essential. Regular assessment of DD levels may facilitate earlier detection of VTE, allowing clinicians to intervene promptly and improve patient outcomes.