Relationship Between red blood cell distribution width and Preoperative deep venous thrombosis of the lower extremity in elderly patients with hip fracture: A Propensity-Score Matched and Conditional Logistic Regression Analysis

Abstract Background: Deep vein thrombosis (DVT) was a severe and common complication that occurred in the patients with hip fractures, and the red blood cell distribution width (RDW) had been confirmed to be a risk factor of preoperative DVT. However, this relationship remains yet clear, and thus this study aimed to elucidate the relationship between RDW and preoperative DVT in the elderly patients with hip fractures. Methods: We retrospectively collected the medical data of elderly patients (≥60 years) with hip fractures who were admitted to our hospital from October 2017 to December 2020. We used the receiver operating characteristic (ROC) curve to determine the optimal cut-off value of RDW, based on which, all patients were divided into the high or low RDW group. A propensity score matching (PSM) in a 1:1 ratio with the caliper value set as 0.02 was performed to balance variables and match cases with controls. Finally, the other potential confounding factors were controlled for by using conditional logistic regression analysis to identify the association between the RDW and preoperative DVT. Results: A total of 2,520 patients were enrolled, the optimal cut-off value of RDW was 14.23%, and 1641 patients had a lower value, while 879 had a lower value. After PSM, 747 pairs constituted the study group. The standardized mean deviations (SMD) of all covariates were less than 0.10 (range, -0.06 to 0.04), indicating the groups were well matched. The conditional logistic regression analysis showed high RDW was associated with 1.83-fold increased risk (adjusted RR, 1.83; 95% CI, 1.28 to 2.62) of preoperative DVT after adjusting the covariates. In parallel, intertrochanteric fracture, high BMI, and longer time to surgery were identified as independent risk factors for preoperative DVT. Conclusion: High RDW level, together with other risk factors, was identified to be independently associated with preoperative DVT in elderly patients with hip fractures, thus facilitating the individualized risk assessment, risk stratification and accordingly development of targeted preventive interventions.