Neutrophil‐to‐Monocyte Ratio as a Predictor of Complications in Deep Neck Infections: A Multi‐Centre Retrospective Study

Objective Deep neck infections (DNIs) remain potentially life‐threatening conditions despite advances in antimicrobial therapy and imaging techniques. This study aimed to evaluate clinical, anatomical and laboratory factors associated with complication development in patients with DNIs, with a particular focus on the prognostic value of the neutrophil‐to‐monocyte ratio (NMR). Methods This retrospective, multi‐centre study included patients diagnosed with DNIs between January 2018 and December 2023 at Harran University Faculty of Medicine Hospital (Şanlıurfa) and Diyarbakır Gazi Yaşargil Training and Research Hospital. Demographic characteristics, comorbidities, infection aetiology, anatomical involvement, clinical presentation and laboratory parameters were analysed. Patients were compared according to the presence or absence of complications. Receiver operating characteristic (ROC) analysis was performed to assess the predictive performance of inflammatory indices. Results A total of 376 patients were included. Odontogenic infections were the most common aetiology, and the submandibular space was the most frequently involved anatomical region. Complications were significantly more common in patients with multi‐space involvement, Ludwig's angina and diabetes mellitus. Patients who developed complications had significantly higher white blood cell counts, neutrophil counts, C‐reactive protein levels and NMR values. ROC analysis demonstrated that NMR showed strong predictive performance for complications (AUC = 0.866). An NMR cut‐off value of 20.53 provided high sensitivity and acceptable specificity for predicting complications. Conclusion Complication development in deep neck infections is closely related to the extent of anatomical spread, comorbid conditions and the severity of systemic inflammatory response. NMR appears to be a promising biomarker for early risk stratification and may provide supportive information for clinical assessment when interpreted alongside clinical and anatomical findings. Further prospective studies are warranted to validate its role in routine practice.