Association of preoperative hemoglobin levels with the risk of pharyngocutaneous fistula after surgery for laryngeal and hypopharyngeal squamous cell carcinoma.

PURPOSE: Pharyngocutaneous fistula (PCF) is a common complication after head and neck surgery. Although preoperative hemoglobin levels have been implicated in PCF development, the nature of this relationship—particularly its potential nonlinearity—has not been fully elucidated. This study aimed to evaluate the association between preoperative hemoglobin levels and PCF risk, with emphasis on characterizing possible nonlinear effects. METHODS: We conducted a retrospective cohort study including 1,507 patients who underwent surgery for laryngeal or hypopharyngeal squamous cell carcinoma between 2000 and 2022. Univariable and multivariable regression models were employed to assess the association between hemoglobin level and PCF occurrence. Nonlinear relationships were examined using smooth curve fitting and generalized additive models (GAM). RESULTS: The overall rate of PCF was 8.09%. Patients who developed PCF had significantly lower preoperative hemoglobin levels (108.76 ± 26.53 g/L) compared to those without PCF (141.93 ± 17.39 g/L; p < 0.001). Each 1-g/L increase in hemoglobin was associated with a 9% reduction in the odds of PCF (OR 0.93, 95% CI: 0.93–0.94; p < 0.001). Multivariable analysis confirmed that hemoglobin was an independent predictor of PCF (adjusted OR 0.93, 95% CI: 0.91–0.94; p < 0.001). A nonlinear relationship was identified with an inflection point at 117 g/L. Below this value, each unit increase in hemoglobin was associated with a more pronounced reduction in PCF risk (OR 0.90, 95% CI: 0.88–0.93; p < 0.001), whereas above this threshold, the protective effect was attenuated. CONCLUSION: Preoperative hemoglobin level is an independent predictor of PCF development, with a particularly strong effect observed below 117 g/L. These findings provide a rationale for individualized perioperative management guided by preoperative hemoglobin levels.