Introduction

Among sleep-related breathing disorders, obstructive sleep apnea (OSA) is one of the most common diseases [1,2,3,4]. OSA is characterized by interruption of airflow caused by collapse of upper airway soft tissue. Due to this cessation of airflow, repeated hypoxemia and hypercapnia occur, which causes chronic systematic inflammation and repetitive sympathetic activation and can lead to development of secondary diseases of cardiovascular, metabolic, or neurologic nature, among others [5, 6]. Though affected individuals often remain asymptomatic early in the disease course, patients later present regularly with a variety of clinical symptoms ranging from nonrestorative sleep to daytime sleepiness and fatigue, depression, reduced drive, and impaired social life [7].

The diagnosis of OSA is usually established using overnight sleep recording in the form of home sleep apnea testing (HSAT) or polysomnography (PSG), from which a variety of measures can be calculated that allow estimation of disease severity. In addition, a variety of patient-reported outcome measures are in use for evaluation of general OSA-related quality of life and specific symptom domains.

Treatment of OSA is required to reduce complications and comorbidities as well as to improve symptoms. Present therapies for OSA are largely dominated by nocturnal ventilation with positive airway pressure (PAP), which was introduced in the early 1980ies and is widely available in most geographic locations [8]. Beside PAP therapy as the gold standard in treatment of OSA, a variety of non-PAP alternatives have been developed and are used to varying degrees. These are increasingly required, since 30 to 50% of patients in whom PAP treatment is initiated discontinue use and may eventually require an alternative treatment [9, 10].

Equally efficacious in selected patients suitable for this kind of treatment and with mild to moderate OSA are mandibular advancement devices (MAD) that increase the retropalatal space to avoid airway obstructions [11]. For patients with positional OSA, devices can be applied that help to avoid a supine sleeping position [12]. Contemporary position therapy devices, which are worn on the chest using a belt, apply sensing technology to detect body position and vibrate when supine posture is recognized to induce a change in body position [13]. In the surgical domain, a large variety of resecting concepts have been developed to address soft tissue collapse, with the most often applied being tonsillectomy in conjunction with uvulopalatopharyngoplasty (UPPP) or multilevel interventions that combine various upper airway procedures [14]. An alternative surgical concept is maxillomandibular advancement to increase the posterior airway space [15]. Over the past decade, hypoglossal nerve stimulation (HNS) has been introduced as a dynamic surgical concept to treat OSA. HNS uses electrical stimulation to activate the main upper airway dilator muscles during sleep to maintain airway patency and thus avoid obstructions [16].

Whilst all these methods have been used for many years and are recommended in the current German guideline, the routine OSA treatment landscape is largely dominated by PAP therapy, though limitations are well documented and include therapy rejection due to low perceived social acceptability and insufficient adherence and discontinuation due to side effects and discomfort [17,18,19,20]. With sleep physicians being central stakeholders for treatment allocation, there is an obvious need to increase the understanding of the decision-making process for alternative non-PAP OSA treatments. Thus, we designed this study to generate insights into the knowledge of alternative treatment concepts among physicians and to further understand barriers in the allocation of those treatments from the sleep physician’s perspective.

Methods

The study was part of a larger research project conducted in 2021 that aimed to assess the status of sleep medical practice and care in Germany using a country-wide survey. In this study, more than 5000 physicians from the outpatient and inpatient sector in Germany were invited to participate in an online survey. The self-administered survey consisted of 32 questions in four categories and addressed various topics relevant to the provision of sleep medical care in Germany. The research methodology and a detailed analysis of the participants have been published previously [21].

Domains relevant for this analysis addressed the following aspects of alternative OSA treatments which were available in Germany routinely at the time when the study was conducted:

  1. 1.

    self-reported knowledge;

  2. 2.

    self-reported annual indications;

  3. 3.

    perceived barriers of care which limit indication of the respective treatments.

Answers were collected using standardized categories for the different items and therapeutic concepts.

Statistical analysis

Statistical analyses of survey data were performed using SPSS (SPSS Statistics 29.0.1, IBM Corp., Armonk, NY, USA) and included descriptive and concluding statistics. P-values of < 0.050 were considered statistically significant. Depending on data distribution and scales, a variety of statistical tests was applied, including Pearson’s chi-squared test, Student’s t‑test, Levene test, and linear regression analysis.

Results

Participants

The sample consisted of 435 participating physicians from multiple medical disciplines providing sleep-related care in the outpatient and inpatient sector. The details of the sample have been described previously and can be considered representative for the care structure of sleep medicine in Germany, which is dominated by providers from internal medicine, mainly with pneumology specialization, and otorhinolaryngology (Table 1 and [21]).

Table 1 Medical disciplines of survey participants and distribution across care sectors
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Self-reported knowledge of alternative OSA treatments

Knowledge of alternative treatments for OSA among German sleep physicians was assessed for the following five treatments: 1) mandibular advancement device (MAD), 2) upper airway surgery (UA surgery, such as tonsillectomy or UPPP), 3) hypoglossal nerve stimulation (HNS), 4) maxillomandibular advancement surgery (MMA), and 5) positional therapy. All therapies were routinely used in Germany when the study was conducted, though not all may have been equally accessible due to, e.g., regional differences in the medical services available.

In general, self-reported knowledge of the therapies was moderate among sleep physicians (Fig. 1), and most participants stated basic knowledge of the five alternative treatments. Only a few reported not knowing certain treatments (MAD = 0.5%; UA surgery = 1.6%; HNS = 3.5%; MMA = 6.9%; positional therapy = 0.5%). Highest knowledge scores were found for MAD treatment and positional therapy, while lowest knowledge was reported for MMA surgery. Except for UA surgery, where self-reported knowledge was lower in the inpatient sector (p = 0.030), no significant differences were found between the two care sectors. Self-reported knowledge correlated negatively with the number of sleep-related trainings [r (374) = −0.161, p = 0.002] and participant age [r (342) = −0.114, p = 0.037]. A positive correlation was found for the number of OSA consultations per year [r (422) = 0.314, p = < 0.001]. No correlation was present for length of sleep-medical practice [r (374) = 0.086, p = 0.098].

Fig. 1
figure 1

Self-reported knowledge of alternative obstructive sleep apnea treatments among physicians in the outpatient and inpatient sectors. MAD mandibular advancement device, UA upper airway, HNS hypoglossal nerve stimulation, MMA maxillomandibular advancement; * = p < 0.050 between sectors

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Indication of alternative OSA treatments

Overall, alternative OSA therapies were reported to be well adopted by sleep physicians in Germany (Fig. 2). Only a small number of participants reported not indicating or referring for any alternative treatments (1.1%). However, among physicians participating in this survey, indication of different alternative treatments varied widely. For example, nonsurgical alternative treatments were reported to be indicated more often than surgical interventions, with indication volumes of 25 or more indications per year reported by 32.5% (MAD) and 47.0% (positional therapy). Among surgical treatments, upper airway surgery was more often indicated than HNS therapy or MMA surgery (> 25 indications: 13.7% vs. 1.6% and 0.6%). For the latter two treatments, most participants reported not indicating or referring any patients (48.3% and 64.4%).

Fig. 2
figure 2

Indication of alternative obstructive sleep apnea treatments by sector. MAD mandibular advancement device, UA upper airway, HNS hypoglossal nerve stimulation, MMA maxillomandibular advancement; * = p < 0.050 between sectors

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Significant differences in indication of alternative OSA treatments were found between care sectors. Physicians from the inpatient sector stated significantly higher indication of UA surgery versus those from the outpatient sector [t(356) = 2.373, p = 0.015] as well as for indication of HNS therapy [t(357) = 2.484, p = 0.169]. For the other three treatments, no statistically significant differences in indications were observed between the sectors (Fig. 2).

Provision of alternative treatments also varied across the responses (Fig. 3). To receive alternative treatments, patients are commonly referred to other clinicians, which is the most common provision mode. This is more pronounced for more specialized treatments like HNS therapy or maxillomandibular advancement, which are provided by a few clinics only. The exception is positional therapy, which 83% of survey participants provide in their own clinic or practice.

Fig. 3
figure 3

Provision of alternative obstructive sleep apnea treatments. MAD mandibular advancement device, UA upper airway, HNS hypoglossal nerve stimulation, MMA maxillomandibular advancement; missing to 100% = not indicating treatment

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Barriers to indicating alternative OSA treatments

To assess potential barriers to the provision of alternative treatments, participants were asked about their perception of five aspects that could impact indications for each therapeutic concept. The aspects presented were 1) no contact for referral, 2) no demand from patients, 3) insufficient evidence, 4) indication unclear, and 5) issues with reimbursement. Barriers that limit indicating or referring for alternative treatments were reported for all alternative OSA therapies surveyed (Table 2). Most barriers were mentioned with MAD treatment (80.7%), HNS (69.2%), and MMA treatment (62.5%). Barriers in the utilization of positional therapy on the other hand were only reported by 43.9% of participants. The distribution of the barriers varied highly across the different treatments (Fig. 4): reimbursement issues were most often mentioned over all treatment categories and those most affected were MAD treatment (57.6% of responses), HNS (19.6% of responses), and positional therapy (18.1% of responses). Physicians in the inpatient sector reported significantly more often reimbursement limitations in general compared to those from the outpatient sector (p < 0.001). No demand from patients was reported mainly for MMA and HNS, while insufficient evidence was most mentioned with UA surgery.

Table 2 Physician-reported barriers to utilizing alternative obstructive sleep apnea treatments (multiple answers allowed per treatment category)
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Fig. 4
figure 4

Distribution of barriers for indication of alternative obstructive sleep apnea therapies across treatments. MAD mandibular advancement device, UA upper airway, HNS hypoglossal nerve stimulation, MMA maxillomandibular advancement; missing to 100% = no barriers reported

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Perception of the different barriers varied between physicians working in the inpatient sectors compared to those from the outpatient sector, though not all differences were statistically significant (Table 2). In general, male participants, pneumologists, and cardiologists reported significantly more often barriers to provision of alternative OSA treatments (p = 0.005, p = 0.012, and p = 0.007).

Multiple linear regression analysis was conducted to test whether age, number of sleep medical trainings, reported cooperation behavior, and self-reported knowledge predict responses on barriers to alternative OSA treatments. The overall regression was statistically significant [R2 = 0.255, F(4, 236) = 4.118, p = 0.003], and it was found that self-reported knowledge of alternative therapies predicted response behavior in items on barriers that limit indication of treatments (β = −0.170, p = 0.015). Additional analysis did not reveal any statistically significant correlations for participant age (p = 0.084), number of annual OSA consultations (p = 0.921), and length of sleep medical practice (p = 0.344). A low positive correlation was found for reporting barriers with the number of sleep medical trainings [r (435) = 0.096, p = 0.045], and a low negative correlation for self-reported knowledge of alternative treatments [r (374) = −0.228, p = < 0.001].

Discussion

With an increasing prevalence of OSA and rising numbers of patients receiving treatment, the need for alternative therapies is also growing, with more patients terminating PAP therapy. Though highly efficacious and cost effective, PAP therapy as the first-line treatment is often not tolerated in chronic use, which leaves many patients with a need for alternatives to control their OSA [17, 18, 22]. This is at least partially accelerated by the lack of structured and adequately funded follow-up pathways for patients using PAP therapy, which contributes to the high rate of PAP termination. In addition, as reported recently by Woehrle et al., large numbers of patients diagnosed OSA do not receive PAP therapy [23]. Though the reasons were not identified in this study, it highlights the need for alternative treatments. Since PAP therapy would have been theoretically available for all patients, they potentially opted against it and could benefit from another form of treatment.

As experts in the field and important influencers of patient decision-making, sleep physicians play a relevant role in the allocation of alternative OSA treatments, and their knowledge and perceptions are crucial for patient access. To the best of our knowledge, this is the first study to evaluate knowledge of, perceived barriers to, and indication of alternative treatments for OSA from the perspective of sleep physicians in Germany. Our study shows a moderate average degree of self-reported knowledge among German sleep physicians from both the inpatient and the outpatient sector. Except for positional therapy, only a few physicians reported expert-level knowledge of alternative OSA treatments. In light of other findings from this study reported earlier, where a majority of participants reported good knowledge of recent clinical guidelines, there might be a different appraisal of high-level knowledge of guidelines and knowledge of individual treatment modalities.

While in general, knowledge of more common alternatives like MAD and positional therapy is higher, understanding of specialized surgical interventions such as HNS, MMA, and UA surgery is lower, which translates into lower self-reported indications for these treatments. On the other hand, participants reported relatively high numbers of indications for alternative OSA treatments, which can be interpreted as these being well accepted among physicians. This is supported by the fact that only a small minority of 1.1% reported not indicating any treatments beside PAP therapy.

Our study underscores one important feature of sleep medicine in Germany, which is the need for multidisciplinary provision of care. This relies on local or regional networks of different medical specialists that collaborate in the provision of services. As such, most alternative treatments are provided after referral to other physicians of a different discipline. The only exception is positional therapy, which is mostly offered within the own clinic or practice. The results presented here are supported by earlier reports from this project that show a high degree of cooperation in sleep medicine, especially among the two disciplines that dominate the provider landscape, namely otorhinolaryngology and respiratory medicine [21]. Since this multidisciplinary cooperation requires significant interaction and communication between providers, ongoing reimbursement challenges in sleep medical services—present in both the outpatient and the inpatient sector—could create disincentives for collaboration and threaten patient access. A potential solution to further increase collaboration and interdisciplinary exchange could be the implementation of local OSA boards, comparable to the “heart team” approach in cardiac care, in which members of the team discuss patient cases and optimal treatment allocation on a regular basis.

Although theoretically, all treatments except MAD, for which coverage was only introduced in 2021, are part of the benefit scheme of statutory insurance, reimbursement by third-party payors is perceived as the most relevant barrier to indication across all alternative treatments assessed. Interestingly, physicians from the inpatient sector perceive reimbursement limitations significantly more often for the treatment options UA surgery and HNS, which are mainly provided in hospitals. A common practice in Germany is ex-post denial of hospital claims by the statutory insurance’s medical service, which is reported to occur frequently and which could influence the perception of sleep physicians for these treatments [24]. This is especially important as HNS therapy was funded under special agreements and only introduced into the regular DRG catalogue in 2021.

Given the invasive nature of surgical treatments, it is not surprising that no demand from patients is reported as a barrier to these alternatives, since surgical treatment in general is often not preferred by patients in comparison to nonsurgical options [25, 26]. Although UA surgery, HNS, and MMA are recommended in OSA practice guidelines published by the German Sleep Society, which require a rigorous assessment of clinical evidence, and randomized clinical trials have been published for these interventions, a fairly large number of participants report insufficient evidence as a barrier to utilizing these treatments [20, 27]. Factors that lead to this perception could not be established from this study but should be a further part of future studies given the importance of this aspect in the provision of alternative treatments and the central role of the physician in the decision-making process.

Limitations

With a large sample size representative of the German care structure in sleep medicine, we believe that this study provides strong evidence to support the findings presented. Nevertheless, the study is subject to some limitations, which should be considered when interpreting the results. Though we were able to recruit a large sample, the overall response rate was only 9%, which appears to be low in comparison to other studies [28]. This response rate is related to the fact that a large database was used to distribute the survey to ensure that all potential physicians were reached. Also, the questionnaire was quite comprehensive and required substantial time to complete, which could have deterred some physicians. However, the geographical distribution of participants and the proportion of participants with regards to the medical disciplines corresponded to a recent analysis of sleep medical care in Germany, as discussed in the initial analysis of the survey [21]. Furthermore, the study was based on a simple survey design that relied on self-reported answers, which creates several issues. Beside overconfidence in reporting knowledge, there is a risk of socially desirable answering behavior which might influence the responses. However, with a relatively large and balanced sample, we believe that the risk of bias is limited. It is also important to have in mind that the survey did not test the knowledge, which might have led to more precise estimation of knowledge. The time burden associated with a more sophisticated survey design was considered too high, and it was decided to use this approach to lower the risk of dropouts. Another limitation arises from the fact that knowledge and perceptions are fluid and subject to constant external influences. Ongoing continuous medical education, changing medical practice guidelines, and reimbursement decisions will impact upon how available treatments are perceived and indicated in routine care. Recently, MAD treatment was added to the benefit catalogue of the statutory health insurance, which will reduce reimbursement limitations present before this decision [29]. Finally, knowledge and perceived barriers are only parts of the actual decision-making process, and other factors, e.g., immediate availability in the local healthcare ecosystem, personal preferences, and administrative aspects, will influence adoption and utilization of treatments. To further assess the factors driving these circumstances, additional research is warranted.

Conclusion

Self-reported knowledge of alternative OSA treatments is moderate among sleep physicians in Germany, and only a minority report expert knowledge. Utilization of these therapies is common but varies significantly, and is often carried out within networks of different medical specialties. Sleep physicians frequently perceive barriers to the provision of those treatments across all alternative treatments, which highlights the need for optimization of care pathways and continuous education of providers. For MAD and positional therapy, reimbursement issues were perceived as most relevant barrier, while insufficient evidence was reported most often for UA surgery, and no demand from patients was perceived as the main barrier to indication of HNS and MMA treatments.