A Simple Scoring System Based on CRP/Alb Ratio, Fasting Glucose, and Surgery Duration for Predicting Postoperative Infection in Older Adult Patients with Intertrochanteric Femoral Fracture: A Retrospective Cohort Study.

Abstract

Background: Postoperative infection is a serious complication in older adults undergoing surgery for intertrochanteric femoral fracture (IFF). This study aimed to develop a simple scoring system and nomogram for predicting postoperative infection using routinely available preoperative indicators.

Methods: A retrospective analysis was conducted on 286 older adult IFF patients (25 with postoperative infection, 261 without) treated at a single tertiary hospital. Optimal cut-off values were determined using the Youden index. Univariate and multivariate logistic regression identified independent risk factors. A nomogram and a simple scoring system (0-3 points) were constructed. Model performance was assessed by AUC, calibration curve, and subgroup analyses. Bootstrap resampling (500 iterations) was used for internal validation.

Results: Multivariate analysis confirmed the CRP/albumin ratio (OR = 2582.84, 95% CI: 201.44-67,929.9, p < 0.001), fasting glucose (OR = 2.82, 95% CI: 1.32-6.73, p = 0.011), and surgery duration (OR = 1.06, 95% CI: 1.01-1.12, p = 0.020) as independent predictors. Optimal cut-offs were 1.85 (CRP/albumin), 7.6 mmol/L (glucose), and 89 minutes (surgery). The scoring system showed infection rates of 0%, 5.6%, 40.9%, and 100% for scores 0, 1, 2, and 3, respectively, with an AUC of 0.932. The full model achieved an AUC of 0.951, with Bootstrap-corrected AUC of 0.945 (95% CI: 0.923-0.951). Calibration was satisfactory (Hosmer-Lemeshow, p = 0.327). Subgroup analyses demonstrated robust performance across gender, BMI, and age groups, with AUCs ranging from 0.922 to 0.982.

Conclusion: In this single-center retrospective cohort, the CRP/albumin ratio, fasting glucose, and surgery duration were independent predictors of postoperative infection in older adults with IFF. The proposed simple scoring system and nomogram provide practical tools for risk stratification; however, external validation in multicenter prospective cohorts is warranted before widespread clinical implementation.