Laboratory Predictors of Early Venous Thromboembolism in Patients with Intertrochanteric Fractures: A Retrospective Cohort Study

Abstract Background Patients with femoral intertrochanteric fracture face a high early post-traumatic risk of venous thromboembolism (VTE). The Caprini risk-assessment model relies only on demographic and medical-history items and lacks laboratory markers reflecting the post-traumatic coagulation-fibrinolysis state. This study aimed to explore associations between laboratory biomarkers measured within 24 h of injury and ultrasound-detected deep vein thrombosis (DVT) occurring within 5 days. Methods This single-centre retrospective cohort enrolled 210 consecutive intertrochanteric-fracture patients who met predefined eligibility criteria and were admitted within 24 h of trauma (see flow diagram, Fig. 1). Patients were classified by lower-limb venous Doppler ultrasonography as DVT (n = 87) or non-DVT (n = 123). Baseline features were compared. Univariable and separate multivariable Firth-penalised logistic regression models were fitted. Because of severe multicollinearity, D-dimer and fibrinogen degradation products (FDP) were fitted in two distinct models. Receiver-operating-characteristic (ROC) curves assessed discriminative ability, and sensitivity analyses were performed. Results Patients with early DVT had significantly lower 24-h D-dimer and FDP concentrations (both P = 0.002). In the primary model (Model A, adjusted for sex, age, BMI, and smoking; n = 210, 87 events), lower D-dimer (OR = 0.961, 95% CI 0.929–0.989, P = 0.004) and lower FDP (OR = 0.983, 95% CI 0.969–0.995, P = 0.003) were independently associated with early DVT-an inverse association opposite in direction to that reported in non-trauma populations. No statistically significant departure from a linear form was detected. ROC analysis yielded modest AUC values (0.603 for D-dimer; 0.605 for FDP). Sensitivity analyses were consistent with the primary estimate, and all participants fell within a single (highest) Caprini risk stratum. Conclusions Lower ultra-early post-injury D-dimer and FDP concentrations were independently associated with ultrasound-detected DVT within 5 days after intertrochanteric fracture in this exploratory analysis. Given their limited standalone discrimination and the absence of demonstrated incremental value beyond the Caprini score, these biomarkers should be regarded as candidate supplementary indicators for future, externally validated prediction models rather than as standalone clinical decision tools.