Post-Operative Hypothyroidism Predicts Fistula Development Following Salvage Oropharyngectomy

Abstract

<h3>Purpose/Objective(s)</h3> Previous work has demonstrated post-operative hypothyroidism adversely affects wound healing in salvage laryngectomy. The purpose of this study is to evaluate the association between wound healing and hypothyroidism in patients undergoing salvage oropharyngectomy. <h3>Materials/Methods</h3> A single-institution retrospective case series was performed. Fifty-three patients who underwent salvage oropharyngectomy for recurrent or second primary oropharyngeal squamous cell carcinoma between 2001 and 2017 after radiation or chemoradiation were included. The principle explanatory variable was post-operative hypothyroidism, defined as thyroid stimulating hormone (TSH) greater than 5.5 mIU/L. The primary endpoints of the study were oropharyngocutaneous fistula development and fistula requiring operation within 30 days. Binary logistical regression multivariate analysis was performed. <h3>Results</h3> Post-operative fistula rate was 35% among hypothyroid patients which was significantly greater when compared to 9.1% among euthyroid patients. Moreover, 20% of patients with hypothyroidism developed a fistula requiring reoperation, while 3% of euthyroid patients developed a fistula requiring re-operative management. In a multivariate analysis, post-operative hypothyroid patients were at a 9.5-fold increased risk of developing a fistula (95% confidence interval [CI] 1.6 – 57.0, p = 0.013). Additionally, post-operative hypothyroid patients were at 13.6-fold increased risk for development of a fistula requiring reoperation (95% CI 1.2 – 160.5, p = 0.038). <h3>Conclusion</h3> Post-operative hypothyroidism in patients undergoing salvage oropharyngectomy is an independent predictor of fistula development and are more likely to require operative management after fistula development. These data support previously published work demonstrating post-operative hypothyroidism as an independent risk factor for fistula development in patients undergoing salvage laryngectomy. This study further supports the role of hypothyroidism management to modulate wound healing and post-operative wound complications.