Effect of Intraoperative Neuromonitoring on the Risks of Recurrent Laryngeal Nerve Injury During Thyroidectomy: A Doubly Robust Approach.

OBJECTIVE

To evaluate the relationship between the use intraoperative neuromonitoring (IONM) during thyroidectomy and the risk of recurrent laryngeal nerve (RLN) injury.

BACKGROUND

The role of IONM in reducing RLN injury during thyroidectomy remains controversial. Several studies on this topic apply conventional multivariable regression to adjust for confounding. However, estimates from this method may be biased due to model misspecification, especially with a rare outcome such as RLN injury.

METHODS

We used a pooled dataset created by linking the 2016-2019 National Surgical Quality Improvement Project General Participant User File with the corresponding Targeted-Thyroidectomy file. The primary outcome was RLN injury rates, and the secondary outcomes were operating time and postoperative length of stay. A doubly robust (DR) estimator, in the form of an inverse-probability-weighted regression adjustment model, was used to estimate the effect of the use of IONM on the risk of RLN injury. Sensitivity analyses was performed.

RESULTS

Twenty-four thousand three hundred seventy patients were evaluated, out of which 15,836 (70%) patients had IONM during thyroidectomy, and RLN injury occurred in 1498 (6.2%) cases. Rates of RLN injury increase with increasing age and BMI and are higher in patients with a cancer diagnosis, previous neck operation, total thyroidectomy, and node dissection. Doubly robust model suggests that the use of IONM was associated with a significant reduction in overall rate of RLN injury [risk ratio 0.77, confidence interval (CI), 0.68-0.87, P <0.001], and postoperative length of stay [-2.5 hours (CI, -4.18 to -0.81 h), P =0.004]. However, IONM use was associated with an increase in operating time [15.41 minutes (CI, 13.29-17.54 minutes), P <0.0001]. Sensitivity analyses revealed that our estimates are largely robust to confounding.

CONCLUSION

In a balanced cohort of patients undergoing thyroidectomy from multiple sites and surgeons participating in National Surgical Quality Improvement Project, the use of IONM during thyroidectomy was associated with reduction in RLN injury.