Development and Validation of a Nomogram Incorporating Changes in Inflammatory Markers for Predicting Complications After Free Flap Reconstruction of Oral and Maxillofacial Defects.

[OBJECTIVE] To investigate the associations between inflammatory markers changes before and after free flap reconstruction and postoperative complications, and to develop and validate a nomogram with perioperative inflammatory markers changes to predict complications.

[METHODS] Eight hundred fifty patients who underwent free flap reconstruction of oral and maxillofacial defects between January 2022 and December 2023 were randomly allocated into the primary and validation cohorts at a 7:3 ratio. In the primary cohort, the authors used logistic analysis to evaluate the adjusted associations between changes in inflammatory markers, including elevation in neutrophil-to-lymphocyte ratio (NLR) and in platelet-to-lymphocyte ratio (PLR), and postoperative complications. In addition, the authors used a generalized additive model (GAM) to visualize the associations. By using the Akaike information criterion, nomograms with and without NLR elevation and PLR elevation were developed. Validation of the nomograms were performed in the primary and validation cohort. Discrimination of the nomograms was assessed by concordance index (C-index), and calibration was assessed by calibration curve.

[RESULTS] Both NLR elevation and PLR elevation demonstrated significant linear relationships with postoperative complications. While NLR elevation was negatively associated with the complications [odds ratio (OR), 0.916; 95% CI: 0.848-0.990; P=0.027], PLR elevation showed a positive correlation with them (OR: 1.618; 95% CI: 1.165-2.247; P=0.004). The nomograms with NLR elevation and PLR elevation had higher C-indexes (0.705 and 0.680, respectively) and better calibration in the primary and validation cohort.

[CONCLUSIONS] NLR elevation and PLR elevation were shown to significantly negatively and positively correlated with complications after free flap reconstruction, respectively. Incorporating these changes in inflammatory markers into the nomogram could increase predictive accuracy. Clinicians could apply this nomogram to develop preventive and treatment strategies.