Validity and Utility of a Risk Prediction Model for Wound Infection After Lower Third Molar Surgery

OBJECTIVES: To externally validate a clinical prediction model for surgical site infection (SSI) after lower third molar (L3M) surgery and evaluate its clinical usefulness. METHODS: We conducted a retrospective cohort study of patients who underwent L3M surgery at Hokkaido University Hospital. The study was designed to evaluate the historical and methodological transportability. Clinical usefulness was evaluated using decision curve analysis on the data of the non-antibiotic-treated patients. RESULTS: We obtained 2543 validation cohorts from April 2020 to March 2023, and 640 non-antibiotic cohorts from July 2010 to September 2023. The incidences of SSI after L3M surgery were 5.3% (135/2543) and 7.7% (49/640) in the validation and non-antibiotic cohorts, respectively. The discrimination ability of the prediction model was acceptable for the external validation cohort (c-statistic: 0.67; 95% CI: 0.62-0.71) and adequate for the non-antibiotic cohort (c-statistic: 0.72; 95% CI: 0.63-0.79). In both cohorts, the model showed excellent calibration between the observed and predicted probabilities. Decision curve analysis showed increased net benefit across a range of meaningful risk thresholds. CONCLUSION: A simple risk prediction model for SSI after L3M surgery demonstrated clinical transportability and usefulness. This model may help surgeons/clinicians determine the appropriateness of prophylactic antibiotics administration for patients in L3M surgery.