Preoperative quantitative quadriceps muscle ultrasound to predict POD for gastrointestinal surgery in older patients.

Objective: Postoperative delirium (POD) is generally associated with increased postoperative adverse events. We aimed to investigate whether preoperative quantitative quadriceps muscle ultrasound could predict POD in older patients after gastrointestinal surgery in order to provide more targeted prevention and treatment measures.

Methods: We prospectively collected data from elderly patients who underwent elective gastrointestinal surgery from August to December 2023 at a tertiary hospital in China. Intergroup difference analysis and univariate and multivariate logistic regression analyses were used to explore independent risk factors. We calculated and assessed the parameters via sensitivity, specificity, the Youden index, and the area under the receiver operating characteristic curve (AUC), calibration curves and the Hosmer-Lemeshow test. The nomogram was validated internally through bootstrap resampling. The decision curve analysis (DCA) was used to evaluate its clinical validity.

Results: A total of 695 patients who underwent gastrointestinal surgery were analyzed in this investigation, among which 137 patients experienced POD with an incidence rate of 19.7%. After conducting multivariate logistic regression analyses using R software, six independent risk factors associated with POD were identified, including age, quadriceps muscle thickness (Q-MT), quadriceps echo intensity (Q-EI), Charlson Comorbidity Index (CCI), preoperative frailty and preoperative Minimum Mental State Examination (MMSE) scores. The AUC value of the model was 0.966 (95% CI: 0.950-0.982; p < 0.05). The calibration curve revealed that the predicted probability of the nomogram was consistent with the actual probability, and the Hosmer-Lemeshow goodness-of-fit test value was 0.811. DCA revealed that the nomogram has a net benefit for POD.

Conclusion: Quantitative quadriceps ultrasound parameters, including the Q-MT and Q-EI, could predict POD after gastrointestinal surgery in older patients. We have developed a new nomogram for predicting POD in older patients who undergo gastrointestinal surgery.

Study registration: The trial was registered in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ) on August 3, 2023, with the registration number of ChiCTR2300074304.