One of the wonderful things about sleep surgery is that it remains a relatively small field. I have had the pleasure of getting to know leading sleep surgeons from around the world through various organizations, such as the International Surgical Sleep Society. Because we know each other well, we share experiences (good and bad) and feel comfortable speaking up when we have questions about someone’s research or a difference of opinions.
As anyone who has read this website or blog can attest, I feel that drug-induced sleep endoscopy (DISE) has an important role in the evaluation and surgical treatment of obstructive sleep apnea. This is based not just on my experience with about 2000 exams but also on numerous published DISE research studies — both my own and performed by others. The most important question about any test is whether it can improve results, and we are now finishing the second study examining this question in a multicenter study of 275 study participants. The first study showed that DISE findings are associated with outcomes of upper airway surgery and I wrote about it in a blog post last year. To be blunt, it was a major effort because it was the most scientific evaluation of this question that has ever been done. It incorporated recorded preoperative DISE videos that were evaluated by 4 surgeons who were blinded to the scoring of the operating surgeon, the type of surgery, and the results of surgery. This was just about the purest way to evaluate whether the findings of DISE before surgery were associated with results and, ideally, what kind of surgery would be best for a patient. Katherine Green from the University of Colorado led this work, and Phillip Huyett from Massachusetts Eye and Ear Infirmary is leading our second, similar study of Inspire Medical’s Upper Airway Stimulation. Both of them completed their fellowship training with us, and I am so proud of their work with these studies and the fact that they are already becoming leaders in sleep surgery.
Not so fast?
In the April 2020 issue of The Laryngoscope, a number of colleagues published a study suggesting that DISE does not improve surgical outcomes. They collected a group of 326 patients from multiple centers and looked at results in those with and without preoperative DISE. They showed that the results for those with DISE were not better than without DISE. I read the article with great interest but was a little surprised that they corrected for differences in age, gender, and body mass index in individual study participants but did not consider the factor most strongly associated with surgery outcomes: tonsil size. I wrote a letter to the editor at the same time that I sent my concerns to the main authors (good friends of mine). Their response was published this month in the journal, but I must say I am not entirely satisfied. They showed that a similar proportion of participants in the DISE and no DISE groups had markedly enlarged tonsils (3+ and 4+ according to our grading system), but they did not redo the statistical analysis to correct for tonsil size. I am not sure why, as it should have been easy to do this. I completely understand the challenges of having multiple surgeons perform blinded review of recorded videos (often surgeons do not save videos, and watching the videos for our study took 40-60 hours). However, I do think it would have been extremely helpful to include tonsil size in the analysis to make the most use of the available data.
The bottom line
We have a difference of opinion on the importance of DISE. Nevertheless, we agree that DISE is not some magical spell that ensures that someone will have perfect results after surgery. However, I do think our study (soon to be studies) is showing us how DISE can improve our ability to select procedures and discuss surgical options with patients.