Development and Validation of a Nomogram for Predicting High-Risk Hidden Blood Loss After Total Knee Arthroplasty.

Abstract

Hidden blood loss (HBL) accounts for 49% of total postoperative blood loss after total knee arthroplasty (TKA), predisposing patients to anemia, infection, and delayed functional recovery. Despite partial elucidation of its pathophysiology, standardized predictive models for HBL remain lacking, rendering current clinical management reliant on subjective judgment and precluding individualized risk stratification. This study aimed to identify predictors of high-risk HBL after TKA and develop a validated visual prediction model integrating multiple clinical parameters. Clinical data from 400 TKA patients were analyzed. The dataset was randomly divided into a training group (70%) and a validation group (30%). Univariate analysis initially screened potential predictors, followed by least absolute shrinkage and selection operator (LASSO) regression for dimensionality reduction and key feature extraction. Multivariate logistic regression identified independent predictors of HBL. A nomogram was constructed and validated through receiver operating characteristic curves, calibration curves, and decision curve analysis (DCA) to assess discrimination, calibration, and clinical utility. Univariate analyses identified 18 significant variables associated with high-risk HBL (P < 0.05). A LASSO regression refined these to eight candidate predictors. Multivariate analyses confirmed weight, preoperative hemoglobin (Hb), postoperative white blood cell count (WBC), and postoperative albumin (ALB) as independent predictors of high-risk HBL after TKA. The nomogram demonstrated the area under the curve of 0.858 (95% confidence interval [CI] = 0.812 to 0.904) and 0.818 (95% CI = 0.719 to 0.917) in the training and validation groups, respectively, indicating good discrimination. Calibration curves demonstrated high agreement between predicted and observed probabilities, supported by a nonsignificant Hosmer-Lemeshow test (P > 0.05). DCA confirmed net clinical benefit across low-to-moderate risk thresholds. The nomogram incorporating weight, preoperative Hb, postoperative WBC, and postoperative ALB demonstrates excellent discrimination, calibration, and clinical utility, enabling early identification of high-risk HBL patients for personalized postoperative management of TKA.