Abstract
Thank you for the opportunity to respond to the letter by Walgama et al. (1) regarding our recent publication entitled “Routine Preoperative Laryngoscopy for Thyroid Surgery Is Not Necessary Without Risk Factors” (2).
The 5987 patients included in this study had all undergone routine preoperative fiber-optic laryngoscopy for vocal cord visualization. They represented consecutive patients undergoing thyroid surgery over the 19-year period. The vocal cord assessments were performed by our otolaryngology, head and neck surgery colleagues. While the clinician conducting the laryngoscopy examination may vary in seniority, any uncertainty in their assessment would be escalated to a senior member of the team. It is from this comprehensive data set that we asked ourselves if it is necessary to perform preoperative fiber-optic laryngoscopy on every patient or was there a set of practical criteria we could define to safely reduce the number of laryngoscopy procedures.
The 2015 American Thyroid Association guidelines (Recommendation 40) recommend voice assessment before thyroid surgery—“This should include the patient's description of vocal changes, as well as the physician's assessment of voice” (3). We strongly support this recommendation. They go on to recommend preoperative laryngeal examination in patients with voice abnormalities, previous cervical or upper chest surgery and known thyroid cancer with posterior extrathyroidal extension or extensive central node metastases (Recommendation 41). We also strongly support this recommendation. Locally advanced thyroid cancer with posterior extrathyroidal extension and/or extensive central node metastases is uncommon, and hence the presence of malignant cytology is not in itself an absolute indication for laryngoscopy. Therefore, the premise of this study was to identify an at-risk group of patients in whom preoperative laryngoscopy is necessary to identify or exclude vocal cord palsy; and conversely, a group of patients in whom preoperative laryngoscopy can be safely left to the discretion of the treating physician.
When comparing the small group (N = 41) with preoperative palsy (vocal cord palsy [VCP] group) and the vast majority (N = 5946) who did not (no palsy [NP] group), we found that there was an over-representation of patients with voice changes, nodule ≥3.5 cm, and previous surgery in the VCP group. Any subjective voice change was considered positive for voice changes in our data set, regardless of the nature or severity. Recognizing that the overall proportion of malignant cases is small in this study, the proportion of malignant cytology was not significantly different between the VCP and NP groups. There were seven patients in the VCP group who had a malignant cytology, but all of them also had voice changes (N = 3), nodule ≥3.5 cm (N = 3), or both (N = 1). Therefore, malignant cytology without the other risk factors was not an independent indicator of potential preoperative palsy. The odds ratios were not reported in the article as we found that the combination of these three factors accounted for 100% of patients with preoperative vocal cord palsy in our cohort. In other words, none of the 3633 patients without any of these three risk factors—voice change, nodules ≥3.5 cm or previous neck surgery—was found to have a preoperative palsy on laryngoscopy. Therefore, the relative odds were thought to be less important. For academic interest, the odds ratios are shown in Table 1.
Frequency of Potential Preoperative Vocal Cord Palsy Risk Factors
CI, 95% confidence interval; OR, odds ratio; NP, no palsy; VCP, vocal cord palsy.
While we estimated a 400AUD cost per case, a full cost-benefit analysis was beyond the scope of this study. The findings of such an analysis would vary widely depending on the individual institution. Our estimate is in fact a conservative one. The single-use flexible fiber-optic laryngoscope used at the time of writing this article was 380AUD, with little to account for the time of the clinician and clinic staff. While the current Australian Medicare Benefits Schedule for a first consultation is 88AUD, and 124AUD for laryngoscopy, the recommended fees for these from the Australian Medical Association schedule are currently 182AUD and 310AUD, respectively. These figures would be in addition to the equipment-related costs, such as purchase costs for single-use scopes, or purchase costs (of multiple scopes), service/maintenance/repair fees, and sterilizing costs for multiuse scopes.
Ultimately, in every clinical situation, a degree of clinician discretion is not only required, but desirable. Similarly, whether a single-institution study is applicable to another institution or surgeon's practice is for the reader to decide. Our study is not disputing the value of preoperative laryngeal examination, nor is it suggesting that intraoperative neuromonitoring can replace laryngoscopy in the detection of preoperative palsy. Our study is simply reporting on our data from nearly 6000 consecutive thyroid surgical patients having routine preoperative laryngoscopy, collected over a 19-year period. In doing so, we aimed to determine if it is possible for us to move from routine to selective preoperative laryngoscopy without missing a pre-existing palsy; and if so, how can patients be selected without compromising safety.