Keywords
obstructive sleep apnea - hypoglossal nerve - implantable neurostimulators - electric
stimulation therapy - patient satisfaction - treatment outcome
Introduction
Obstructive sleep apnea (OSA) is a sleep-related breathing disorder characterized
by repetitive partial or complete upper airway obstruction which often results in
decreased arterial oxygen saturation and arousal from sleep.[1] The current gold standard treatment of moderate-to-severe OSA is continuous positive
airway pressure (CPAP).[2] However, compliance and long-term use of CPAP is rather low.[3] Alternative treatments include custom-made oral appliance therapy (OAT), positional
therapy and upper airway surgery. Since evidence-based reviews do not uniformly support
the efficacy of these treatments for moderate-to-severe sleep apnea, a new therapy
is desirable.[4]
[5] Upper airway stimulation (UAS) with electric activation of the hypoglossal nerve
has emerged as a promising treatment for patients with moderate-to-severe obstructive
sleep apnea who have failed CPAP. Upper airway stimulation has shown favorable success
and low morbidity.[6]
[7]
[8]
[9] The aim of the present study was to retrospectively analyze the single-center results
in terms of surgical success, respiratory outcomes, subjective outcome measures, and
adverse events (AEs) in patients with OSA treated with upper airway stimulation.
Methods
Study Design and Population
An observational retrospective single-center cohort study was conducted at the department
of otorhinolaryngology in the St. Antonius Hospital. Patients were included in this
study if they were diagnosed with OSA and underwent implantation of an upper airway
stimulation system. One-year follow-up data had to be available. In the Netherlands,
the main inclusion criteria for implantation of UAS are failure of or intolerance
to treatment with CPAP, an apnea-hypopnea index (AHI) between 30 and 50 events per
hour, including less than 25% central apneas, and a body-mass index (BMI) < 32 kg/m2. The exclusion criteria include a complete concentric collapse at velopharyngeal
level objectified during drug-induced sleep endoscopy, severe restrictive or obstructive
pulmonary disease, moderate-to-severe pulmonary arterial hypertension, severe valvular
heart disease, New York Heart Association class III or IV heart failure, recent myocardial
infarction or severe cardiac arrhythmias (within the past 6 months), persistent uncontrolled
hypertension despite medical use, active psychiatric disease, coexisting non-respiratory
sleep disorders that would confound functional sleep assessment and expected future
indications for a magnetic resonance imaging (MRI) scan of the chest or the abdomen.
Upper Airway Stimulation System
The UAS system (Inspire Medical Systems Inc., Maple Grove, MN) consists of a respiration
sensor, programmable implanted pulse generator (IPG), and stimulating electrodes.
The sensor is placed between the internal and external intercostal muscles and detects
respiratory efforts from chest excursions that are analyzed by the IPG. The IPG is
implanted below the clavicle and delivers stimulation synchronized with the respiratory
cycle to the stimulation electrode. The stimulation electrode is placed on the anterior
branches of the hypoglossal nerve and cervical spinal nerve 1 (C1). Upon stimulation,
these nerves cause forward protrusion of the tongue by stimulating the genioglossus
muscle. Furthermore, stimulation of C1 causes an anterosuperior displacement of the
hyoid bone, both increasing the size of the oropharyngeal airway. Additionally, previous
studies have shown that the effect of upper airway stimulation is not limited to the
level of the tongue base, but it also improves airway patency at the level of the
palate caused by palatoglossal coupling.[10]
[11]
Objective Outcome Measures
In-laboratory polysomnography (PSG) was performed at baseline in all patients. After
implantation of the UAS in-laboratory PSG was performed at 2, 6, and 12 months. Polysomnography
included electroencephalography, electrooculography, surface electromyography, nasal
airflow, and air temperature, thoracoabdominal movements, pulse oximetry, body position,
and snoring sounds. Breathing was recorded with nasal pressure and temperature sensors.
Scoring of electronic raw data was performed manually, following the recommendations
of the American Academy of Sleep Medicine.[12] Apnea was defined as a decrease of at least 90% of airflow from baseline for > 10 seconds.
Hypopnea was defined as a decrease of at least 30% of airflow from baseline for > 10 seconds,
associated with either an arousal or ≥ 3% arterial oxygen saturation decrease. The
mean AHI was calculated. The oxygen desaturation index (ODI) ≥ 3% was defined as the
mean number of arterial oxygen desaturations ≥ 3% per hour. The ODI ≥ 4% was defined
as the mean number of arterial oxygen desaturations ≥ 4% per hour. Other PSG parameters
collected included the apnea index (AI), the AHI in supine position, the AHI in non-supine
position, and mean arterial oxygen saturation (SpO2). Patient therapy use was measured
in hours per week and was collected during the in-laboratory PSG. Surgical success
was defined according to the Sher criteria: a reduction in baseline AHI of more than
50%, and a postoperative AHI of less than 20 events per hour.[13] An additional classification was made for patients with a reduction in baseline
AHI of more than 50% and a postoperative AHI of less than 15 events per hour. Adverse
events were collected at the 6- and 12-month visits and were subdivided into procedure-
and therapy-related AEs.
Subjective Outcome Measures
The Epworth sleepiness scale (ESS), which was designed to assess the extent of daytime
sleepiness, was collected at baseline in all patients.[14] Additionally, all patients completed the ESS at 6- and 12-month visit. An adapted
clinical global impression (CGI) scale, which was originally designed for patients
with mental disorders, was used by the physician to compare the present clinical condition
to baseline. The CGI ranges from 1 (very much improved) to 6 (very much worse). Furthermore,
all patients received a questionnaire regarding patient experience with therapy (PET).
This questionnaire consists of four questions regarding patient satisfaction:
-
- How does UAS therapy compare against your previous experience with CPAP?
-
- What is the likelihood of choosing UAS therapy again?
-
- What is the likelihood of recommending UAS therapy to friends/family?
-
- Overall, how satisfied are you with UAS therapy?
Ethical Considerations
All procedures performed in studies involving human participants were in accordance
with the ethical standards of the institutional and/or national research committee
and with the 1964 Helsinki Declaration and its later amendments or comparable ethical
standards. Data on study subjects were collected and stored anonymously to protect
personal information. Informed consent was obtained prior to data collection.
Statistical Analysis
The statistical analysis was performed by using the IBM SPSS Statistics for Windows,
Version 24.0 (IBM Corp., Armonk, NY, USA). Normally distributed continuous data are
presented as means with standard deviations. Non-normally distributed continuous data
are presented as median with interquartile range (IQR). Categorical variables are
presented as frequencies with percentages. Comparisons between groups were performed
using Chi-squared tests for categorical variables, paired t test and Wilcoxon rank sum test for continuous variables. A two-tailed p-value < 0.05 was considered statistically significant.
Results
Baseline Characteristics
This retrospective analysis consists of 25 patients undergoing implantation of upper
airway stimulation between January 2018 and September 2019, baseline characteristics
are mentioned in [Table 1]. Ninety-six percent of the patients were male with a mean age of 62.40 ± 9.45 years.
The mean body-mass index (BMI) was 28.18 ± 2.34 kg/m2. The median baseline AHI was 37.40 (33.7–45.6) e/h, with a mean ESS of 10.28 ± 5.26.
The median ODI ≥ 4% was 20.10 (16.5–27.2) e/h. Fourteen patients (56%) previously
underwent a tonsillectomy. All other patients had small tonsils, varying from tonsil
size 1 to 2. The median Mallampati score was 3.
Table 1
Baseline characteristics
|
Measurement
|
N = 25
|
|
Male patients
|
24 (96%)
|
|
Age (mean ± SD; years)
|
62.40 ± 9.45
|
|
BMI (mean ± SD; kg/m2)
|
28.18 ± 2.34
|
|
AHI (median (Q1-Q3); e/h)
|
37.40 (33.7–45.6)
|
|
ODI ≥4% (median (Q1-Q3); e/h)
|
20.10 (16.5–27.2)
|
|
ESS (mean ± SD)
|
10.28 ± 5.26
|
Abbreviations: AHI, apnea-hypopnea index; BMI, body-mass index; ESS, Epworth sleepiness
scale; ODI, oxygen desaturation index; Q1, quartile 1; Q3, quartile 3; SD, standard
deviation.
Objective Outcome Measures
A complete overview of the objective outcome measures at 6- and 12-month follow-up
is shown in [Table 2]. The total median AHI at the 6-month follow-up significantly decreased from 37.40
(33.7–45.6) e/h to 8.10 (3.9–15.0) e/h (p < 0.001). Both the median AHI in supine position and non-supine position significantly
decreased, from 59.30 (38.4–77.4) e/h to 22.60 (9.6–31.9) e/h and from 25.60 (15.3–27.2)
e/h to 5.90 (2.3–12.4) e/h, respectively (p = 0.001; p < 0.001). The median ODI ≥ 4% significantly decreased from 20.10 (16.5–27.2) e/h
to 4.50 (1.7–7.4) e/h (p < 0.001). The mean therapy usage at the 6-month follow-up was 6.96 ± 1.59 hour/night.
The median AHI at 12-month follow-up significantly decreased to 8.70 (4.8–12.7) e/h
(p < 0.001). The median AHI in supine position and non-supine position was 20.70 (12.5–36.9)
e/h and 8.40 (2.7–11.3) e/h, respectively (p < 0.001; p < 0.001). The median ODI ≥ 4% was 6.00 (5.0–12.6) e/h (p < 0.001). The mean therapy usage at 12-month follow-up was 5.83 ± 1.70 hour/night.
Table 2
Outcome measures at 6- and 12-month follow-up
|
Measurement
|
Preoperative
|
Time point
|
Postoperative
|
P-value
|
|
AHI (median (Q1-Q3); e/h)
|
37.40 (33.7–45.6)
|
6 months
|
8.10 (3.9–15.0)
|
< 0.001[*]
|
|
12 months
|
8.70 (4.8–12.7)
|
< 0.001[*]
|
|
AI (median (Q1-Q3); e/h)
|
16.00 (7.6–30.0)
|
6 months
|
2.20 (0.9–3.7)
|
< 0.001[*]
|
|
12 months
|
3.50 (1.1–5.5)
|
< 0.001[*]
|
|
Supine AHI
(median (Q1-Q3); e/h)
|
59.30 (38.4–77.4)
|
6 months
|
22.60 (9.6–31.9)
|
0.001[*]
|
|
12 months
|
20.70 (12.5–36.9)
|
< 0.001[*]
|
|
Non-supine AHI
(median (Q1-Q3); e/h)
|
25.60 (15.3–27.2)
|
6 months
|
5.90 (2.3–12.4)
|
< 0.001[*]
|
|
12 months
|
8.40 (2.7–11.3)
|
< 0.001[*]
|
|
ODI ≥ 3%
(median (Q1-Q3); e/h)
|
32.90 (27.9–36.9)
|
6 months
|
11.60 (6.8–16.4)
|
< 0.001[*]
|
|
12 months
|
14.30 (10.7–25.2)
|
< 0.001[*]
|
|
ODI ≥ 4%
(median (Q1-Q3); e/h)
|
20.10 (16.5–27.2)
|
6 months
|
4.50 (1.7–7.4)
|
< 0.001[*]
|
|
12 months
|
6.00 (5.0–12.6)
|
< 0.001[*]
|
|
Mean SpO2 (mean ± SD)
|
93.91 ± 1.30
|
6 months
|
94.08 ± 1.54
|
0.472[**]
|
|
12 months
|
93.71 ± 1.70
|
0.346[**]
|
|
ESS (mean ± SD)
|
10.28 ± 5.26
|
6 months
|
7.95 ± 2.93
|
0.007[**]
|
|
12 months
|
7.04 ± 3.61
|
0.002[**]
|
|
Therapy usage
(mean ± SD; h/night)
|
–
|
6 months
|
6.96 ± 1.59
|
–
|
|
12 months
|
5.83 ± 1.70
|
–
|
Abbreviations: AHI, apnea-hypopnea index; AI, apnea-index; BMI, body-mass index; ESS,
Epworth sleepiness scale; ODI, oxygen desaturation index; Q1, quartile 1; Q3, quartile
3; SD, standard deviation, SpO2, arterial oxygen saturation.
* Wilcoxon signed-rank test
** Paired t-test
Subjective Outcome Measures
The mean ESS significantly decreased from 10.28 ± 5.26 to 7.95 ± 2.93 and 7.04 ± 3.61
respectively at 6- and 12-month follow-up (p = 0.007; p = 0.002) ([Table 2]). The summarized data of CGI at 6- and 12-month follow-up is shown in [Table 3]. At the 6-month follow-up, the CGI of 96% of the patients is minimally, much, or
very much improved. At the 12-month follow-up, all patients were at least minimally
improved in comparison to baseline. [Table 4] shows the results of the PET questionnaire. At the 6- and 12-month follow-ups, respectively,
84.61% and 69.57% of the patients declared UAS was better than CPAP therapy; 100%
and 82.61% would choose UAS again; 84.61% and 73.91% would recommend UAS to friends/family;
92.31% and 69.57% were satisfied with UAS therapy.
Table 3
Clinical global impression
|
Clinical global impression
|
6 months
|
12 months
|
|
Very much improved
|
6 (24%)
|
11 (47.83%)
|
|
Much improved
|
12 (48%)
|
8 (43.78%)
|
|
Minimally improved
|
6 (24%)
|
4 (17.39%)
|
|
No change
|
1 (4%)
|
0 (0%)
|
|
Minimally worse
|
0 (0%)
|
0 (0%)
|
|
Much worse
|
0 (0%)
|
0 (0%)
|
|
Very much worse
|
0 (0%)
|
0 (0%)
|
Table 4
Patient experience with therapy
|
Patient Experience with Therapy
|
6 months
|
12 months
|
|
How does your UAS therapy compare against your previous experience with CPAP?
|
UAS is much better than CPAP
|
76.92%
|
65.22%
|
|
UAS is better than CPAP
|
7.69%
|
4.35%
|
|
CPAP and UAS are equal
|
0%
|
0%
|
|
CPAP is better than UAS
|
0%
|
4.35%
|
|
CPAP is much better than UAS
|
0%
|
4.35%
|
|
N/A – No experience with CPAP or did not use CPAP long enough
|
15.38%
|
21.74%
|
|
What is the likelihood of choosing UAS therapy again?
|
Strongly agree
|
84.62%
|
65.22%
|
|
Agree
|
15.38%
|
17.39%
|
|
Neither agree nor disagree
|
0%
|
8.7%
|
|
Disagree
|
0%
|
4.35%
|
|
Strongly disagree
|
0%
|
4.35%
|
|
What is the likelihood of recommending UAS therapy to friends/family?
|
Strongly agree
|
69.23%
|
43.48%
|
|
Agree
|
15.38%
|
30.43%
|
|
Neither agree nor disagree
|
15.38%
|
17.39%
|
|
Disagree
|
0%
|
8.7%
|
|
Strongly disagree
|
0%
|
0%
|
|
Overall, how satisfied are you with UAS therapy?
|
Very satisfied
|
38.46%
|
21.74%
|
|
Satisfied
|
53.85%
|
47.83%
|
|
Neither satisfied nor dissatisfied
|
7.69%
|
21.74%
|
|
Dissatisfied
|
0%
|
4.35%
|
|
Very dissatisfied
|
0%
|
4.35%
|
Abbreviations: CPAP, continuous positive airway pressure; UAS, upper airway stimulation.
Surgical Success
The surgical success rate according to the Sher criteria was 92% at the 6-month follow-up
and 96% at the 12-month follow-up. Additionally, at the 6-month follow-up, 76% met
the additional criteria of ≥ 50% reduction from baseline AHI and a postoperative AHI
of ≤ 15. At the 12-month follow-up, 88% had met the additional criteria.
Adverse Events
A complete overview of reported AEs is presented in [Table 5]. Nine patients (36%) reported at least one adverse event at the 6-month follow-up.
Ten AEs were reported in total, with stimulation-related discomfort being the most
common, reported 7 times (28%). Two patients (8%) developed a submental hematoma postoperatively.
One patient (4%) developed a postoperative wound infection. At the 12-month follow-up,
7 patients (28%) reported at least one AE, with a total of 8 AEs reported. Three patients
(12%) still experienced stimulation-related discomfort. Two patients (8%) experienced
tongue abrasion. One patient (4%) experienced dentofacial changes of the lower teeth,
and two patients (8%) needed an additional barbed stitch pharyngoplasty due to persistent
velopharyngeal collapse as a result of lack of palatoglossal coupling.[11] No severe or irreversible AEs were reported.
Table 5
Adverse events
|
Time point
|
Overall AE rate[*]
|
Adverse event
|
Frequency of AE reported
|
|
Total reported[**]
|
Frequency of AE[***]
|
Mild[****]
|
Moderate[****]
|
Severe[****]
|
|
6 Months
|
9 (36%)
|
Tongue weakness
|
10
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Swallowing/speech related AE
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Discomfort related to incision/scar
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Discomfort related to IPG
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Infection
|
1 (4%)
|
1 (4%)
|
0 (0%)
|
0 (0%)
|
|
Other procedure related AE[±]
|
2 (8%)
|
2 (8%)
|
0 (0%)
|
0 (0%)
|
|
Stimulation related discomfort
|
7 (28%)
|
7 (28%)
|
0 (0%)
|
0 (0%)
|
|
Tongue abrasion
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Insomnia/arousals
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Revision intervention
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Other therapy related AE
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
12 Months
|
7 (28%)
|
Tongue weakness
|
8
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Swallowing/speech related AE
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Discomfort related to incision/scar
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Discomfort related to IPG
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Infection
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Other procedure related AE
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Stimulation related discomfort
|
3 (12%)
|
3 (12%)
|
0 (0%)
|
0 (0%)
|
|
Tongue abrasion
|
2 (8%)
|
2 (8%)
|
0 (0%)
|
0 (0%)
|
|
Insomnia/arousals
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Revision intervention
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
0 (0%)
|
|
Other therapy related AE[±±]
|
3 (12%)
|
3 (12%)
|
0 (0%)
|
0 (0%)
|
Abbreviations: AE, adverse event; IPG, implanted pulse generator.
* This number represents the total number of patients who reported at least one AE
** This number represents the total number of AEs reported at this time point
*** This number represents the number and percent of patients who reported this AE
**** This number represents the number and percent of patients who reported this AE with
each severity of the AE reported
± Two patients developed a submental hematoma postoperatively.
±± One patient experienced dentofacial changes of the lower teeth, two patients needed
an additional barbed reposition pharyngoplasty due to lack of palatoglossal coupling.
Discussion
The present study aimed to retrospectively analyze the long-term postoperative outcomes
of UAS in patients with moderate to severe OSA with CPAP failure or intolerance. Upper
airway stimulation significantly improved respiratory parameters measured by PSG.
The overall surgical success rate measured by the Sher criteria was 92% and 96% at
the 6- and 12-month follow-ups, respectively. Additionally, there was a significant
decrease in ESS measured at the 6- and 12-month follow-ups.
Thaler et al. recently published the results of 382 patients enrolled in the ADHERE
upper airway registry.[10] They found a significant reduction in median AHI from 32.8 e/h to 6.3 e/h and 9.5
e/h at the 6- and 12-month follow-ups, respectively. The surgical success rate, according
to the Sher criteria, was 85% and 69%, respectively. They found a significant reduction
in the median ESS from 11.0 to 7.0 and 6.0, respectively. The mean therapy usage at
12-month follow-up was 5.7 hour/night. Ninety-two percent of investigators reported
improvement with treatment after the participant received an UAS system; 93% of participants
reported overall satisfaction with UAS treatment; 95% preferred UAS over CPAP; 94%
would choose UAS again if asked; and 96% would recommend UAS to family and friends.
Adverse events were reported by 46% at the 6-month follow-up and 32% at the 12-month
follow-up. Previously, Heiser et al. also published results of the ADHERE upper airway
registry.[9] Reporting on 508 patients, the median AHI decreased from 34.0 e/h to 5.7 e/h and
7.0 e/h, respectively, at the posttitration and the final follow-up visits. The surgical
success rate, according to the Sher criteria, was 92% and 81%, respectively. The mean
ESS decreased significantly from 11.8 to 7.7 and 6.7, respectively. Ninety-four percent
of physicians rated improvement on the CGI, which persisted in 93% at the final visit.
Ninety-six percent of the subjects reported that UAS was better than CPAP therapy
post-titration and at the final follow-up visit; 95% stated that they would undergo
UAS again at the post-titration visit; and 94% at the final follow-up visit. Ninety-three
percent reported that they would recommend UAS to family and friends, which increased
to 96% at the final follow-up visit. Ninety-one percent reported that, overall, they
were satisfied with UAS therapy at the post-titration visit, and 94% at the final
follow-up visit. Boon et al. also reported on the ADHERE upper airway registry and
reported similar outcomes to those of Thaler et al. and Heiser et al.[7] Mehra et al. recently published a parallel arm study design to compare objective
sleep apnea measures, and patients reported outcomes in those who received UAS approval
versus denial in a multi-national prospective study.[15] In 250 patients treated with UAS, they found a significant reduction in median AHI
from 31.3 e/h to 10.1 e/h at the 12-month follow-up. There was a significant decrease
in the mean ESS from 13.0 to 6.0. Freedom from procedure-related AEs was present in
97% of those who underwent UAS. Freedom of therapy-related AEs was present in 90%.
Woodson et al. reported 5-year outcomes of patients receiving UAS therapy. They reported
a surgical success measured by the Sher criteria of 75%. The responder rate at the
5-year follow-up was 63%.[8] Earlier, Strollo et al. found a significant reduction in AHI from 29.3 e/h to 9.0
e/h and ODI from 25.4 to 7.4 e/h in moderate-to-severe OSA patients 12-months after
implantation, with a surgical success rate of 66%.[6] The mean ESS significantly decreased from 11.6 to 7.0.
In comparison to previously published studies, the baseline AHI was higher in our
patient population. This can be explained by the fact that, in the Netherlands, costs
for treatment with UAS are only reimbursed for patients with an AHI between 30 and
50 e/h, while in most other countries the inclusion range is 15 to 65 e/h. The postoperative
AHI was similar to those of earlier studies, indicating that the reduction in AHI
is larger than in previous studies. The surgical success rate according to the Sher
criteria was also higher than in previous studies. The reduction in ESS and the CGI
was similar to what was mentioned by previous authors. The answers to the PET questionnaire
were less positive in this cohort in comparison to previous descriptions of larger
cohorts. A possible explanation can be that the two patients who received an additional
barbed reposition pharyngoplasty due to lack of palatoglossal coupling were dissatisfied
due to the fact that they needed additional surgery. This has largely influenced the
results due to the small sample size. The adverse event rate was similar to the AE
rate mentioned by Thaler et al.[10] However, Mehra et al. reported a lower AE rate.[15] In this cohort, no severe or irreversible AEs were reported. Stimulation-related
discomfort was the most common AE reported. This is generally a short-term problem,
and most patients do not experience discomfort after an intensive titration period.
In the present cohort, the AHI in non-supine position showed a larger decrease in
comparison to baseline than the AHI in supine position. A possible explanation for
this is that in our experience during in-laboratory titration visits, in supine position
a higher stimulation level is needed than in non-supine position. However, this stimulation
level is often not tolerated by the patients, causing discomfort and waking them up
at night, forcing them to lower the stimulation themselves. This is probably the reason
why the AHI in non-supine position shows a larger decrease than the AHI in supine
position.
It is notable that, at the 12-month follow-up, the success rate according to the Sher
criteria was higher than the success rate at the 6-month follow-up. This indicates
that long and intensive follow-up shows improvement of respiratory parameters. The
ESS was also lower at the 12-month follow-up, indicating that patients experienced
less OSA-related complaints. In contrast, the answers to the PET questionnaire were
less positive at the 12-month follow-up. A possible explanation can be that the two
patients who received an additional barbed reposition pharyngoplasty due to lack of
palatoglossal coupling were dissatisfied due to the fact that they needed additional
surgery. Preoperative screening measures are needed to identify patients without palatoglossal
coupling. Additionally, not all patients are aware of the intensive titration that
is needed in the first year after implantation. Further counseling and intensive follow-up
are needed to maintain favorable results.
Clinical Relevance
Obstructive sleep apnea is associated with cardiovascular and metabolic consequences
and is also linked with increased overall mortality.[16] Therefore, in patients with moderate-to-severe OSA and CPAP failure or intolerance,
alternative treatment options are important. In this patient cohort in the Netherlands,
UAS shows a high surgical success rate with no severe or irreversible AEs. This is
similar to the results of previous studies in other countries. Therefore, UAS is an
effective and safe alternative in patients with CPAP failure or intolerance.
Limitations and Strengths
The present study is not without limitations. In the Netherlands, the inclusion criteria
for UAS include a BMI < 32, whereas, worldwide, the inclusion criteria range up to
a BMI of 35. Additionally, patients with a complete concentric collapse at the velopharyngeal
level were excluded. It is possible that this introduces a selection bias that has
positively influenced our results. However, a complete concentric collapse at the
velopharyngeal level is currently globally used as an exclusion criterion. Additionally,
the results represent the experience of one center. The small sample size of this
study is a limiting factor. The published series from Amsterdam, by Vonk et al., describes
a larger cohort.[17] However, this is the first study conducted in the Netherlands that reports on long-term
follow-up results. Additionally, both objective and subjective outcome measures are
reported as well as therapy usage. All patients were followed-up with PSG, whereas,
in previous studies reporting on the ADHERE registry, the AHI was based on both PSG
and home sleep tests.
Conclusion
Upper airway stimulation proved to be a safe and effective treatment for OSA in patients
with CPAP failure or intolerance, with a surgical success rate of 96%. Overall patient
satisfaction was high, and no severe or irreversible AEs were reported. However, it
is possible that the existing in and exclusion criteria for UAS therapy in the Netherlands
have positively influenced our results.
