Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA) learning curve: a regression analysis of complication rates and severity

Background: Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA) is a natural orifice transluminal endoscopic surgery that offers a truly scarless approach to thyroidectomy. Introduced in 2008, there is a growing body of literature establishing it as a safe endoscopic approach for thyroid procedures. While it is not yet widely practiced, it is quickly growing in popularity. As more surgeons begin to add this technique to their repertoire the question of the learning curve has to be examined. Methods: Case series from the initial TOETVA operations of four surgeons at three different hospitals were examined. Binomial and ordinal logistic regression were used to characterize the changes in complication rate and severity as they related to case number in the series. Statistics were performed in Minitab and SAS. Results: Each surgeon performed between 23 and 40 TOETVA operations for a total of 130 cases. Binary logistic regression shows a negative relationship between case number and complication rate (P < 0.001, Odds Ratio: 0.91). Ordinal logistic regression shows a negative relationship between case number and complication severity (P < 0.001, Odds Ratio: 1.07). The maximum slope of improvement of complication rate occurred at case number 12. Conclusion: The most significant decrease in complications for TOETVA occurs at case 12. As case number progresses, there is a significant decrease in both the risk of a complication occurring and of the severity of that complication. These results support the previously published data on TOETVA learning curve based on operative time.