Blood test parameters for predicting severe odontogenic infection in the head and neck region: A retrospective study

Background: Severe odontogenic infections in the head and neck region, especially necrotizing soft tissue infection (NSTI) and deep neck abscess, are potentially fatal due to their delayed diagnosis and treatment. Contrast-enhanced computed tomography images are useful for detecting abscesses, including NSTI. However, clinically, it is often difficult to distinguish the disease (NSTI and deep neck abscess) in its early stage from cellulitis, and the decision to perform contrast-enhanced computed tomography imaging is often a challenge; thus, diagnostic tools for early diagnosis are desirable. This retrospective case-control study aimed to examine the utility of routine blood tests as an adjunctive diagnostic tool for NSTI in the head and neck region and deep neck abscesses. Methods: Severe odontogenic infections in the head and neck region that required hospitalization were classified as follows: Group I (cellulitis), Group II (cellulitis with shallow abscess formation), Group III (deep neck abscess), and Group IV (NSTI). At admission, Inflammatory markers were calculated according to the blood tests. In addition, a decision tree analysis was performed to discriminate between Groups I + II and Groups III + IV. Results: There were 271 patients: 123, 61, 74, and 13 in Groups I, II, III, and IV, respectively. Immediately after diagnosis, all patients underwent urgent incisional drainage and debridement in Groups III and IV. Additionally, all inflammatory markers were higher in Groups III and IV and were remarkably useful for the exclusion diagnosis for Group IV. The decision tree analysis showed that the classification accuracy was 89.3%, with the systemic immune-inflammation index (SII) and C-reactive protein + neutrophil-to-lymphocyte ratio being particularly useful. Conclusions: Inflammatory markers calculated using routine blood tests can be helpful as an adjunctive diagnostic tool in the early diagnosis of potentially fatal bacterial infectious diseases in the head and neck region. An SII of ≥ 282 or < 282 but with a C-reactive protein + neutrophil-to-lymphocyte ratio of ≥ 25 indicates a serious need for contrast-enhanced computed tomography imaging.