Risk factors for preoperative isolated calf muscle vein thrombosis in elderly patients with hip fracture and development of a predictive nomogram: a retrospective study.

backgroundDeep vein thrombosis (DVT) is a common perioperative complication in elderly patients with hip fractures and may lead to life-threatening pulmonary embolism (PE). Isolated calf muscle vein thrombosis (ICMVT), a prevalent subtype of DVT, is often asymptomatic and easily overlooked. Despite its clinical significance, current research on ICMVT remains limited, and there is a lack of validated tools for early identification. This study aimed to determine the incidence and independent risk factors of preoperative ICMVT in elderly patients with hip fractures. In addition, we sought to develop a nomogram-based predictive model using readily available clinical parameters to facilitate early recognition and targeted intervention in high-risk patients.

methodsWe conducted a retrospective analysis of 673 elderly patients with hip fractures who were treated at our institution between June 2020 and June 2023. Patients were categorized into groups based on the presence or absence of preoperative isolated calf muscle vein thrombosis (ICMVT), as confirmed by duplex ultrasonography. Clinical and laboratory data were collected and compared. Univariate analysis followed by multivariate logistic regression was performed to identify independent risk factors associated with preoperative ICMVT. A predictive nomogram model was subsequently developed. The model's performance was assessed in terms of discrimination, calibration, and clinical utility using the area under the receiver operating characteristic (ROC) curve, calibration plots, and decision curve analysis (DCA), respectively.

resultsThe incidence of preoperative isolated calf muscle vein thrombosis (ICMVT) was 16.5% (111 of 673 patients). Multivariate logistic regression analysis identified the following independent risk factors for ICMVT: platelet distribution width (OR = 0.83, 95% CI: 0.75-0.91), D-dimer level (OR = 1.06, 95% CI: 1.02-1.11), total protein (OR = 0.92, 95% CI: 0.88-0.95), and serum potassium (OR = 0.39, 95% CI: 0.24-0.61). A predictive nomogram incorporating these variables demonstrated moderate discrimination, with an area under the receiver operating characteristic (ROC) curve of 0.739 in the training cohort and 0.742 in the validation cohort. Calibration plots showed good agreement between predicted and observed outcomes. Decision curve analysis (DCA) indicated a favorable net clinical benefit within a threshold probability range of 5% to 50%.

conclusionsPlatelet distribution width, D-dimer, serum potassium, and total protein were identified as independent predictors of preoperative ICMVT in elderly patients with hip fractures. The proposed nomogram demonstrated moderate discriminative ability and may assist in early risk stratification. Further prospective validation is required before clinical application.