Oral appliance therapy (OAT) can be an effective treatment option for patients with obstructive sleep apnea unable to tolerate continuous positive airway pressure. We hypothesize that drug-induced sleep endoscopy (DISE) can be useful in identifying patients who will benefit from OAT.
A retrospective review of all patients who underwent DISE (DISE group) between January 2014 and June 2016 was carried out. We included patients if they received OAT based on recommendations made by DISE findings. A control group was designed by selecting a sample of patients undergoing polysomnography (PSG) with an oral appliance in place who had not undergone prior DISE (no DISE group). The two cohorts were compared to evaluate the hypothesis.
A total of 20 patients fit inclusion criteria for the DISE group and 20 patients for the no DISE group. There was no difference between the DISE and no DISE cohorts with respect to mean age, sex, pre-OAT body mass index, post-OAT body mass index, or pre-OAT PSG characteristics including: apneahypopnea index (AHI), oxygen desaturation nadir, or Epworth Sleepiness Scale score. There was a significantly lower treatment AHI (P = .04) and increased number of patients reaching an AHI less than 5 events/h with OAT therapy (P = .04) in the DISE group.
Patients showing increased airway dimensions at the level of the velum and/or oropharynx with a jaw thrust may benefit the most from OAT. The use of DISE to identify this subset of patients is helpful in optimizing outcomes with OAT.
Huntley C, Cooper J, Stiles M, Grewal R, Boon M. Predicting success of oral appliance therapy in treating obstructive sleep apnea using drug-induced sleep endoscopy. J Clin Sleep Med. 2018;14(8):1333–1337.
Current Knowledge/Study Rationale: Oral appliance therapy is an effective means of treating obstructive sleep apnea in those patients unable to tolerate positive pressure therapy with continuous positive airway pressure or bilevel positive pressure. However, we are limited in our ability to predict which patients will succeed with oral appliance therapy.
Study Impact: With this study, we found improvement in the size of the airway with a jaw thrust maneuver during drug-induced sleep endoscopy to be predictive of improved treatment outcomes when compared to a cohort not undergoing sleep endoscopy.
Obstructive sleep apnea (OSA) is a disease characterized by recurrent upper airway obstruction during sleep, affecting a substantial proportion of the population. These patients suffer from diminished quality of life and daytime sleepiness. In addition, they are at risk for cardiovascular and metabolic comorbidities including hypertension, stroke, and diabetes.1,2 A recent systematic review by Senaratna and colleagues showed the prevalence of OSA to range from 9% to 38%, which was increased in men and with increasing age.3
Numerous options are available for the treatment of OSA with continuous positive airway pressure (CPAP) as first-line therapy. However, for those patients unable to tolerate CPAP use, other options are available and include body positioning devices, surgical intervention, and oral appliance therapy (OAT).
Drug-induced sleep endoscopy (DISE) has come to the forefront as an adjunctive technique in the evaluation of upper airway obstruction. It has shown benefit over the Mueller maneuver in identifying the site and severity of collapse.4,5 By localizing the site of obstruction, DISE aids in the customization of the treatment plan.6
To date, there have been no data assessing the predictive effect DISE may have on OAT treatment success. We hypothesize that DISE can be useful in identifying patients likely to benefit from OAT. We will evaluate OAT outcomes in patients showing improvement in size of the retropalatal and retrolingual airway with a jaw thrust maneuver during DISE and compare them to a cohort not undergoing DISE.
After institutional review board approval, we constructed a case control study designed to assess the predictive effect of DISE on OAT. We retrospectively reviewed the senior author's surgical database of all patients undergoing DISE between January 2014 and December 2016. We reviewed the surgical report of the DISE and recorded the character and severity of collapse at the level of the velum, oropharynx, tongue base, and epiglottis. We subsequently reviewed the patients' charts and documented treatment recommendations based on DISE findings, demographic variables, whether they presented for OAT evaluation, and whether an oral appliance was obtained. We included patients who had a prior diagnosis of OSA (mild, moderate, and severe), prior polysomnography (PSG) data available, were unable to tolerate CPAP, were recommended for OAT based on DISE findings, obtained an oral appliance, and had a posttreatment sleep study performed. PSG scoring criteria from The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications version 2.3 were used. Hypopnea was defined as a drop in respiratory signal by at least 30% for 10 seconds and at least a 4% desaturation.
We then designed a control group by reviewing those patients undergoing a sleep study with an oral appliance in place at the Jefferson Sleep Disorders Center during the study period, who did not undergo DISE, and also had pretreatment sleep study data available. We collected demographic data, PSG data prior to institution of OAT, and PSG data with the oral appliance in place.
To compare the two cohorts, “DISE” and “no DISE,” we used a Mann-Whitney U test to compare demographic, pretreatment PSG, and posttreatment PSG data. We used a Fisher exact test to compare treatment success, and rates of posttreatment AHI < 15, < 10, and < 5 events/h between cohorts. Statistical analysis was done using SPSS software, version 24 (IBM Corp, Armonk, New York, United States). We defined treatment success as a posttreatment AHI < 20 events/h with a 50% improvement from baseline. This is modeled after the commonly used definition of surgical success adopted from the manuscript by Sher.7
At our institution, we conduct the DISE procedure with propofol sedation and use a modification of the VOTE classification to assess the site, pattern, and severity of collapse.8 After appropriate sedation is reached, a flexible bronchoscope is passed through the nose to visualize and evaluate the velum, oropharynx, base of tongue, and epiglottis. After initial assessment, we perform a jaw thrust maneuver during which the anesthesiologist places his or her hands behind the angle of the mandible and pushes the patient's jaw anteriorly, simulating the jaw position with an oral appliance in place. At this point we reevaluate the airway. Patients who show significant improvement in the retrolingual and retropalatal airspace are deemed candidates for OAT. We defined a significant improvement in the retrolingual and retropalatal airway with a jaw thrust as an ability to see the arytenoids and at least the posterior two-thirds of the true vocal folds and an increase of an estimated 3 mm or more at the level of the velum, respectively. Estimation of size improvement was made using the bronchoscope as a guide, which is 5.5 mm in diameter.
Those patients deemed candidates for OAT are then referred to our oral surgery department where they are counseled on the details of OAT. If they select this treatment modality, a custom-fit appliance is created, the patient will adjust the appliance to symptomatic effect, and we will repeat the PSG to assess treatment outcome.
Upon review of the data, we found 567 patients undergoing DISE during the study period. All procedures were performed by the senior author. At the level of the velum, 2.5% had no obstruction, 59.2% had obstruction in an anterior-posterior pattern, and 38.3% had obstruction in a concentric pattern. At the level of the oropharynx, 30.3% had no obstruction, 35.8% had partial obstruction, and 33.9% had complete obstruction. At the level of the tongue base, 11.1% had no obstruction, 45.6% had partial obstruction, and 43.3% had complete obstruction. At the level of the epiglottis, 9.3% had no obstruction, 41.5% had partial obstruction, and 49.2% had complete obstruction. Of this cohort, 102 were recommended to OAT as their primary treatment method. Sixty-two patients presented to oral surgery for OAT evaluation, 39 obtained an oral appliance, and 20 had posttreatment sleep study data available.
A total of 40 patients met our inclusion criteria. This consisted of 20 patients undergoing pretreatment DISE (DISE group) and 20 patients not undergoing DISE prior to OAT (no DISE group). The mean age of the DISE group was 54.55 years and consisted of 14 men and 6 women. The mean age of the no DISE group was 61.95 years and it consisted of 14 men and 6 women. See Table 1 for comparison of the demographic data. A total of 55% of the DISE group (11/20) had pretreatment sleep study data obtained from a polysomnogram and 45% (9/20) from a portable type 3 sleep study. Of those having a pretreatment PSG, 9 of the 11 underwent posttreatment PSG. The other two patients were assessed by a portable type 3 sleep study. A total of 80% of the no DISE group (16/20) had pretreatment sleep study data obtained from PSG and 20% (4/20) from a portable type 3 sleep study. Of those having a pretreatment PSG, 14 of the 16 had a posttreatment PSG. The other two were assessed by a portable type 3 sleep study. Mean total sleep time (TST), sleep efficiency (SE), arousal index (AI), and percentage of stage N1, N2, N3, and R sleep documented in the pretreatment PSG reports are presented in Table 1. The baseline PSG AHI, O2 nadir, and Epworth Sleepiness Scale (ESS) score did not vary between cohorts (Table 1). The mean TST, SE, AI, and percentage of stage N1, N2, N3, and R sleep documented in the posttreatment PSG reports are presented in Table 2. The posttreatment PSG AHI, O2 nadir, and ESS score of both groups are also shown in Table 2. The posttreatment AHI and ESS score showed significant differences between cohorts (both P = .04).
Demographic and pretreatment PSG data from both cohorts.
Demographic and pretreatment PSG data from both cohorts.
Demographic and posttreatment PSG data from both cohorts.
Demographic and posttreatment PSG data from both cohorts.
In the DISE group, 75% of patients attained treatment success, 85% reached a treatment AHI < 15 events/h, 70% reached a treatment AHI < 10 events/h, and 45% reached a treatment AHI < 5 events/h. In the no DISE group, 50% of patients attained treatment success, 60% reached a treatment AHI < 15 events/h, 45% reached a treatment AHI < 10 events/h, and 15% reached a treatment AHI < 5 events/h. There was no difference in the proportion of patients reaching a posttreatment AHI < 10 events/h with P = .10. More patients in the DISE group achieved treatment success and a treatment AHI < 15 events/h and these approached significance, with P = .09 and .08, respectively. Significantly more patients in the DISE group reached a treatment AHI < 5 events/h (P = .04) (Figure 1).
Comparison of rates of treatment success.
Treatment success was defined as a 50% decline in AHI to a value less than 20 events/h. * = significant difference between cohorts. AHI = apnea-hypopnea index.
Comparison of rates of treatment success.
CPAP has long been the first line option for the treatment of OSA, touting benefits in quality-of-life measures and improvements in systemic comorbidities. Studies have reproducibly shown that CPAP has a substantial effect on quality of life and daytime sleepiness, improving ESS and fatigue severity scores.9–11 In addition, treatment with CPAP has shown benefit in controlling atrial fibrillation, hypertension, and markers of diabetes mellitus.12–14
However, only a proportion of patients with OSA who require treatment are able to tolerate CPAP. Many studies use a definition of CPAP adherence as usage for greater than 4 h/night. Using this definition, adherence rates range widely across the literature and can achieve rates as high as 80%, using close follow-up, patient phone calls, and telemedicine to improve usage.15
Because a substantial number of patients with OSA are going untreated, secondary to their inability to use CPAP, other options are necessary. OAT is a widely used and accepted alternative means of treating OSA in CPAP-intolerant patients. Recent American Academy of Sleep Medicine clinical practice guidelines recommend OAT use in patients with OSA who are intolerant of CPAP.16
A recent survey study by Bachour et al. showed their cohort of patients with OAT to have an 81% compliance rate to therapy with a mean decrease in AHI from 27 to 10 events/h.17 When compared directly with CPAP, studies have shown variable outcomes with many finding OAT to be equivalent to CPAP. Phillips et al.18 compared OAT and CPAP using mean arterial pressure as their primary endpoint, finding no difference between the two therapies. They also assessed ESS and Functional Outcomes of Sleep Questionnaire scores, finding no difference between CPAP and OAT.18 Doff et al.19 followed patients treated with CPAP and OAT over 2 years. They found greater improvement in overall AHI in the CPAP group, but no difference in the rate of successful treatment, Functional Outcomes of Sleep Questionnaire scores, or ESS scores.19 Marklund et al. found a mean treatment AHI of 7.5 events/h and female sex, supine-dependent apnea, and mild apnea predictive of success with OAT.20
In an effort to further customize OAT and predict successful outcomes, remotely controlled mandibular protrusion (RCMP) devices have been developed. These devices adjust the degree of mandibular protrusion in small increments, during a sleep study, in an effort to identify the optimal settings to manage an individual patient's apnea. This limits the laborious titration of traditional oral appliances and condenses the process into 1 night, similar to a CPAP titration. Sutherland et al.21 conducted a study using the MatRx system (Zephyr Sleep Technologies Inc., Calgary, Canada) in which they used the outcome of the RCMP titration sleep study to predict success or failure of therapy compared to a follow-up full-night sleep study. They found a sensitivity, specificity, positive predictive value, and negative predictive value of 81.8%, 92.9%, 90%, and 86.7% respectively, and concluded the RCMP system had good predictive accuracy to the outcome of OAT.21 Kastoer et al. performed a review during which they summarized a number of studies using various RCMP and found them to be predictive of therapeutic outcome with OAT.22
With this study, we use DISE as a means of identifying patients likely to succeed with OAT. Okuno et al. evaluated patients with nasopharyngolaryngoscopy and found a greater cross-sectional area at the level of the velopharynx and oropharynx/hypopharynx in those responding to OAT.23 Vroegop et al. performed a study in which they performed DISE on patients with an oral appliance in place and correlated improvement in airway obstruction with PSG outcomes. They found those patients with relief of obstruction at all levels of the airway with OAT had a higher chance of response to therapy compared to patients with either partial or no relief of obstruction.24
Our findings suggest that improvement in the retrolingual and retropalatal airway size during DISE while thrusting the mandible forward is predictive of successful treatment with OAT. Compared to a control group of patients undergoing OAT treatment, but not DISE, we found lower treatment AHI and a higher proportion of patients reaching a treatment AHI less than 5 events/h in patients undergoing DISE with favorable findings. This provides an alternative option for predicting success in OAT in settings where RCMP devices are not available.
We recognize that this study has limitations, namely its small sample size and retrospective design. Unfortunately, only 20 of the 39 patients who had pretreatment DISE and underwent OAT had a posttreatment sleep study. The 19 patients lost to follow-up may have noted complete resolution of symptoms or found no benefit and given up on therapy. The outcome in these patients is speculative and the lack of follow-up introduces bias into the results. Although few in number, some patients in both the DISE and no DISE groups had a posttreatment type 3 sleep study when they were evaluated by PSG prior to any intervention. Type three sleep studies are known to underestimate the severity of OSA and this may affect our outcome data. In addition, our study protocol was based on a subjective increase in airway size, without detailed measurements of the cross-sectional area or amount of jaw thrust. This was not compared to the amount of mandibular protrusion achieved through OAT, introducing variability between what was seen surgically and clinically. Future work measuring changes in airway size, designed in a prospective manor, comparing OAT outcomes in patients with favorable and unfavorable DISE findings would corroborate our results. Using this design, sensitivity, specificity, positive predictive value, and negative predictive value of DISE in predicting OAT outcomes could be calculated.
DISE can be a useful means of selecting patients likely to succeed with OAT. Patients showing increased airway dimensions at the level of the velum and oropharynx with a jaw thrust during DISE benefited more from OAT than a control group of all patients not undergoing DISE.
Work for this study was performed at Thomas Jefferson University. All authors have seen and approved the manuscript. The authors report no conflicts of interest.