Nomogram construction and validation for hypoalbuminemia after total hip arthroplasty in patients with hip fractures

To investigate the risk factors for hypoalbuminemia after total hip arthroplasty (THA) in patients with hip fractures and to establish and validate a risk prediction nomogram. A retrospective analysis was conducted on the clinical data of 688 patients with hip fractures who underwent THA at The Affiliated Hospital of Qingdao University between January 2021 and June 2025. There were 261 males and 427 females. Fracture types included 441 cases of femoral neck fracture and 247 cases of femoral intertrochanteric fracture. Patients were divided into a hypoalbuminemia group ( n = 209) and a normal albumin group ( n = 479) according to whether hypoalbuminemia occurred postoperatively. Differences in general data were compared between the two groups, including age, gender, body mass index (BMI), smoking history, drinking history, comorbidities (hypertension, diabetes, cerebrovascular disease, cardiovascular disease), fracture type, American Society of Anesthesiologists classification, anesthesia type, operative duration, intraoperative blood loss and postoperative drainage volume. Preoperative laboratory examinations, including albumin (ALB), red blood cell count, hemoglobin (HB), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), platelet count (PLT), fibrinogen, activated partial thromboplastin time, D-dimer and serum calcium, were also included in the analysis. Parameters with P < 0.05 in univariate logistic regression were included in multivariate logistic regression to identify independent risk factors for postoperative hypoalbuminemia. The nomogram was developed using R software. Receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) were used to evaluate the model. ROC curve analysis was performed to evaluate predictive performance, and the DeLong test was used to compare AUCs. Significant differences were observed between the hypoalbuminemia group and the normal albumin group in age, BMI, diabetes, operative duration, intraoperative blood loss, preoperative ALB, preoperative HB, preoperative CRP, preoperative ESR, preoperative PLT and preoperative D-dimer ( P < 0.05). Multivariate logistic regression showed that age, diabetes mellitus, BMI, operative duration, intraoperative blood loss, preoperative ALB, preoperative HB and preoperative ESR were independent risk factors for postoperative hypoalbuminemia in hip fracture patients undergoing THA ( P < 0.05). The nomogram incorporating these risk factors yielded an area under the ROC curve of 0.880 (95% CI 0.849–0.911) in the training set and 0.889 (95% CI 0.840–0.938) in the validation set. Both calibration curve and DCA indicated favorable accuracy and clinical utility in both cohorts. ROC curve analysis showed that the combined model achieved the optimal predictive performance for the target outcome, which was significantly superior to all single indicators (all P < 0.001). Advanced age, lower BMI, diabetes mellitus, longer operative duration, more intraoperative blood loss, lower preoperative albumin, lower preoperative hemoglobin and higher preoperative ESR are independent risk factors for postoperative hypoalbuminemia in patients undergoing THA for hip fractures. The nomogram prediction model established for these factors can integrate preoperative clinical data, is suitable for rapid clinical evaluation, and has good predictive ability.