Optimizing Preoperative Venous Thromboembolism Risk Assessment in Elderly Hip Fracture Patients: A Refined Caprini Model Integrating D-Dimer and Injury-to-Admission Time.

BackgroundThe Caprini risk assessment model (RAM) is widely used to evaluate venous thromboembolism (VTE) risk across diverse patient populations. However, the original risk stratifications may require modification for hip fracture patients to improve predictive accuracy. This study aimed to optimize VTE prediction by refining the Caprini model and integrating additional predictive factors.MethodsThis retrospective cohort study included 1114 elderly hip fracture patients screened at Peking Union Medical College Hospital between May 2012 and February 2023. A modified VTE prediction model was developed by integrating D-dimer levels and injury-to-admission time into the Caprini RAM. The sensitivity, specificity, and the area under the curve (AUC) of the model were determined to assess its predictive performance.ResultsThe revised Caprini model effectively stratified patients into three VTE risk levels on the basis of their scores: 14.0% for ≤9, 24.0% for 10-11, and 39.4% for ≥12. Both the Caprini score and risk level demonstrated better predictive ability than D-dimer did (AUCs: 0.606 and 0.614 vs 0.552). Among patients admitted within one day after injury, the D-dimer levels were significantly higher in VTE patients compared with non-VTE patients from day 3 onwards (