Are subjective assessments of snoring sounds reliable?

Management of primary snoring in adults: A scoping review examining interventions, outcomes and instruments used to assess clinical effects

While various treatment options for primary snoring are available, evidence-based recommendations to determine the optimal intervention remain unestablished. To inform future directions of research to guide clinical decision-making, this scoping review was conducted to map the existing evidence on interventions for primary snoring, the outcomes and instruments used to assess their clinical effects in adults. The feasibility of conducting further systematic reviews and comparing outcomes across these therapies using network meta-analysis was also assessed. Of the 1673 records identified, 38 interventional studies met the inclusion criteria with three-fifths of them being before-after studies. The most common reason for study exclusion was results being reported for patients with primary snoring and obstructive sleep apnoea (OSA) combined. Interventions were surgical (73 %), behavioural and the use of devices/medications. Twenty-six common outcomes were identified and categorised into six domains. Fifty-nine instruments were used to assess the outcomes and based mainly on non-validated questionnaires. Our findings indicated (1) the need for randomised controlled trials with strict discrimination between patients with primary snoring and OSA, (2) further network meta-analyses using some outcomes is feasible, and (3) a core outcome set to inform standardised reporting for future research should be developed.

Effect of hypoglossal nerve stimulation on snoring: an evaluation using objective acoustic parameters

STUDY OBJECTIVES

Hypoglossal nerve stimulation is an established therapy for sleep apnea syndrome. Whether or not this therapy on snoring and nighttime noise exposure is effective and how strong this effect may be has not been objectively investigated thus far and was the aim of this study.

METHODS

In 15 participants (14 males; age: 30-72 years; mean: 51.7 years), polysomnography and acoustic measurements were performed before and after hypoglossal nerve stimulation.

RESULTS

The therapy led to a significant improvement in sleep apnea (apnea-hypopnea index from 35.8 events/h to 11.2 events/h, P < .001). Acoustic parameters showed a highly significant reduction in the average sound pressure level (42.9 db[A] to 36.4 db[A], P < .001), averaged sound energy, A-weighted (LAeq; 33.1 db[A] to 28.7 db[A], P < .001), snoring index (1,068 to 506, P < .001), percentage snoring time (29.7-14.1%, P < .001), and psychoacoustic snore score, the latter being a measure of annoyance due to snoring (47.9 to 24.5, P < .001).

CONCLUSIONS

This study was able to show for the first time by means of objective acoustic and psychoacoustic parameters that hypoglossal nerve stimulation can not only cause a significant improvement in sleep apnea but also has a positive effect on snoring and thus noise annoyance experienced by the bed partner.

CLINICAL TRIAL REGISTRATION

Registry: German Clinical Trials Register; Name: Effect of Hypoglossal Nerve Stimulation on Snoring: An Evaluation Using Objective Acoustic Parameters; URL: https://drks.de/search/de/trial/DRKS00032354; Identifier: DRKS00032354.

CITATION

Fischer R, Vielsmeier V, Kuehnel TS, et al. Effect of hypoglossal nerve stimulation on snoring: an evaluation using objective acoustic parameters. J Clin Sleep Med. 2024;20(3):363-370.

How to objectively measure snoring: a systematic review

PURPOSE

Snoring is the most common symptom of obstructive sleep apnea. Various objective methods of measuring snoring are available, and even if the measurement is performed the same way, communication is difficult because there are no common reference values between the researcher and clinician with regard to intensity and frequency, among other variables. In other words, no consensus regarding objective measurement has been reached. This study aimed to review the literature related to the objective measurement of snoring, such as measurement devices, definitions, and device locations.

METHODS

A literature search based on the PubMed, Cochrane, and Embase databases was conducted from the date of inception to April 5, 2023. Twenty-nine articles were included in this study. Articles that mentioned only the equipment used for measurement and did not include individual details were excluded from the study.

RESULTS

Three representative methods for measuring snoring emerged. These include (1) a microphone, which measures snoring sound; (2) piezoelectric sensor, which measures snoring vibration; and (3) nasal transducer, which measures airflow. In addition, recent attempts have been made to measure snoring using smartphones and applications.

CONCLUSION

Numerous studies have investigated both obstructive sleep apnea and snoring. However, the objective methods of measuring snoring and snoring-related concepts vary across studies. Consensus in the academic and clinical communities on how to measure and define snoring is required.

The Annoying Nature of Snoring Sounds Is Not Only about Intensity: A Pilot Study on Exposed Test Subjects

This study aims to assess (i) which acoustic characteristics of snoring sounds are associated with the annoying nature of snoring sounds; (ii) whether listeners’ heart rates correlate with their perceived annoyance; and (iii) whether perceived annoyance is different between listeners with different experiences with their bedpartners’ snoring sounds. Six snoring epochs with distinct acoustic characteristics (viz., reference, high pitch, high intensity, short interval, irregular intensity, and irregular intervals) were collected from snoring patients. Twenty physicians and technicians were involved in the healthcare of snoring patients, and were divided into three groups based on personal experience with their bedpartners’ snoring sounds (viz., non-snoring, snoring but not annoying, and snoring and annoying). The test subjects listened to each epoch and rated its level of annoyance. Listeners’ heart rates were also recorded during the test using a finger plethysmograph. Within the limitations of this study, it was found that, compared with other snoring sounds, snoring sounds with high intensity and irregularity were associated with higher perceived annoyance. However, higher perceived annoyance of snoring sound was not reflected in heart rate-related parameters. In addition, listeners’ personal experiences do not seem to affect their perceived annoyance.

Definition of the snoring episode index based on the analyses of snoring parameters and the apnea hypopnea index

Although snoring is the most common subjective symptom in obstructive sleep apnea (OSA), an international consensus on the definition of snoring is lacking. This study aimed to define snoring by analyzing correlations between snoring parameters and the apnea hypopnea index (AHI). We retrospectively analyzed the polysomnography data of patients with OSA. A snoring event was defined when airflow pressure was > 200 microbar. We included four snoring parameters. Snoring percentage was defined as the cumulative time of snoring events divided by total sleep time. A snoring episode was defined as the occurrence of ≥ 3 consecutive snoring events, and the snoring episode index was defined as the number of snoring episodes per hour. The average and longest durations of snoring episodes were also investigated. The study enrolled 5035 patients. Their mean AHI was 26.5/h and the mean snoring episode index was 19.2/h. Although the four snoring parameters showed significant correlations with the AHI, the snoring episode index showed the strongest positive correlation with the AHI (r = 0.741, P < 0.001). The snoring episode index may be used as a definition of snoring from the perspective of a highly positive correlation with the AHI.

The acoustical and perceptual features of snore-related sounds in patients with obstructive sleep apnea sleeping with the dynamic mandibular advancement system MATRx plus®

PURPOSE

The effect of snoring on the bed partner can be studied through the evaluation of in situ sound records by the bed partner or unspecialized raters as a proxy of real-life snoring perception. The aim was to characterize perceptual snore events through acoustical features in patients with obstructive sleep apnea (OSA) with an advanced mandibular position.

METHODS

Thirty-minute sound samples of 29 patients with OSA were retrieved from overnight, in-home recordings of a study to validate the MATRx plus® dynamic mandibular advancement system. Three unspecialized raters identified sound events and classified them as noise, snore, or breathing. The raters provided ratings for classification certainty and annoyance. Data were analyzed with respect to respiratory phases, and annoyance.

RESULTS

When subdividing perceptual events based on respiratory phase, the logarithm-transformed Mean Power, Spectral Centroid, and Snore Factor differed significantly between event types, although not substantially for the spectral centroid. The variability within event type was high and distributions suggested the presence of subpopulations. The general linear model (GLM) showed a significant patient effect. Inspiration segments occurred in 65% of snore events, expiration segments in 54%. The annoyance correlated with the logarithm of mean power (r = 0.48) and the Snore Factor (0.46).

CONCLUSION

Perceptual sound events identified by non-experts contain a non-negligible mixture of expiration and inspiration phases making the characterization through acoustical features complex. The present study reveals that subpopulations may exist, and patient-specific features need to be introduced.

Efficacy of pillar implants to reduce snoring and daytime sleepiness

OBJECTIVE

To measure the efficacy of pillar implants in reducing snoring.

MATERIALS AND METHODS

A total of 30 adult patients who underwent pillar implants were assessed preoperatively and at 1, 3, 6 and 12 months after the implantation. Improvement was measured using snoring frequency, visual analog scale for snoring loudness, and Epworth sleepiness scale for daytime sleepiness.

RESULTS

The mean snoring frequency, loudness and Epworth score were reduced from 6.9, 9.2 and 7.4 at the baseline to 5, 5.9 and 5.6, respectively, at 12 months postoperatively (all p < 0.03). The partial implant extrusion rate was 6.7%.

CONCLUSION

We suggest that a pillar implant procedure should be considered before proceeding to more morbid surgeries in patients with snoring and daytime sleepiness.

Snoring patterns during home polysomnography. A proposal for a new classification

PURPOSE

Snoring is a very common disorder, but, at present, there is no universally accepted classification for the condition. The main aim of this paper is to introduce a home sleep monitoring-based classification of common snoring patterns in simple snorers and in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

MATERIALS AND METHODS

In total, 561 consecutive patients with a history of snoring, either simple or associated with apnea, were enrolled in this home sleep monitoring study. Analysis of the polysomnographic traces and the snoring sensor allowed the main patterns of snoring and their characteristics to be determined.

RESULTS

Four patterns of snoring were identified. In a spectrum of increasing severity (mild, moderate or severe), snoring can be episodic, positional, continuous, or alternating, whereas in obstructive sleep apnea syndrome, the snoring events only occur between successive respiratory obstructive events. In mild snoring, the episodic pattern is the most frequent, whereas in moderate and severe snoring, the continuous snoring pattern occurs in most cases.

CONCLUSIONS

The proposed classification of snoring patterns would be beneficial for providing a realistic disturbance index, for the selection and evaluation of the outcomes of surgical techniques.

The relationship between self-reported habitual snoring and hyperuricemia among Chinese urban adults: a cross-sectional study

BACKGROUND

Growing evidence suggests an independent relationship between habitual snoring and metabolic abnormalities. Currently, there are few data available on the association between snoring and hyperuricemia. Therefore, we evaluated the cross-sectional association between snoring and serum uric acid (UA) concentration and ascertain the effects of different snoring intensities on hyperuricemia among Chinese urban adults in Nanjing.

METHODS

We performed a cross-sectional study including 7699 participants (4197 men and 3502 women) from Nanjing Drum Tower Hospital aged ≥18 years over a two year (ie, 2016-2018) period. All participants were divided into four groups based on Snoring scores. Questionnaires, physical examinations and biochemical tests were conducted. Hyperuricemia was defined as levels of serum UA > 6.8 mg/dL in males and >6.0 mg/dL in females. We used a generalized linear model to investigate the association between snoring and serum UA concentration and logistic regression model to investigate the association between snoring and likelihood of having hyperuricemia in the age-, sex-adjusted model and in a multivariable model adjusting for demographic factor, plasma lipid profiles, blood glucose, blood pressure, smoking, and alcohol consumption.

RESULTS

The prevalence of hyperuricemia was 10.05% in the studied population and gradually increased across the snoring scores (P < 0.0001). We found that mild snoring, moderate, and severe snoring intensity were associated with high serum UA in the age-, sex-adjusted model and in a multivariable model adjusting for demographic and lifestyle/behavioral risk factors. The association was insisted with the addition of variables related to clinical outcomes such as diabetes, hypertension, and high-cholesterol levels.

CONCLUSIONS

Our results showed self-reported habitual snoring was associated with higher serum UA concentration among Chinese urban adults. Findings of this study indicate the significance of early detection and treatment of snoring to prevent hyperuricemia.

Systematic review of the different aspects of primary snoring

Primary snoring, also known as simple or non-apnoeic snoring, is regarded as the first stage of sleep disordered breathing without severe medical consequences for the snorer and co-sleeper. Although it is a highly prevalent phenomenon in the general population, our knowledge is limited because of the lack of a consensus on terminology. This systematic review of the aspects used in the definitions of simple/primary snoring was conducted to obtain an inventory of current practices and compare these definitions with the conceptual definition of the American Academy of Sleep Medicine. PubMed and Web of Science were searched from July 2016 onwards without any language limitations, and 362 references were obtained. After selection based on titles, 39 remained, among which 29 contained a definition or reference to a definition. In 69% of the studies, a cut-off <5 apnoea/Hypopnoea events per hour of sleep on the Apnoea-Hypopnoea Index was used. Despite this tendency, the cut-offs ranged from 0 to <15/h. Unfortunately, the cut-off and occasional requirements did not match the conceptual definition of the American Academy of Sleep Medicine. A consensus must be reached on an operational and clinically relevant definition based on the clear conceptual definition.

The Relationship between Simple Snoring and Metabolic Syndrome: A Cross-Sectional Study

PURPOSE

This cross-sectional study was performed to assess the relationship between simple snoring and metabolic syndrome (MetS).

METHODS

A total of 5635 participants including 300 healthy volunteers without snoring allegedly were initially included from 2007 to 2016. Polysomnographic variables, anthropometric measurements, and biochemical indicators were collected. The polynomial linear trend test was used to assess the linear trend across snoring intensity for metabolic score, and logistic regression was used to evaluate the odds ratios (ORs) for MetS after controlling for age, sex, obesity, smoking status, and alcohol consumption.

RESULTS

The final study population consisted of 866 participants. Simple snorers showed more severe metabolic disorders and higher prevalence of MetS than nonsnorers. A significant linear trend was observed between snoring intensity and metabolic score. Simple snoring was significantly associated with increased odds for MetS among all participants (OR = 2.328, 95% CI: 1.340-4.045) and female participants (OR = 2.382, 95% CI: 1.136-4.994) after multivariable adjustment. With regard to MetS components, simple snoring was significantly associated with increased odds for hypertension (OR = 1.730, 95% CI: 1.130-2.650), abdominal obesity (OR = 1.810, 95% CI: 1.063-3.083), and hyper-triglycerides (TG) (OR = 1.814, 95% CI: 1.097-2.998) among all participants, with hypertension (OR = 3.493, 95% CI: 1.748-6.979) among males and with abdominal obesity (OR = 2.306, 95% CI: 1.245-4.270) and hyper-TG (OR = 2.803, 95% CI: 1.146-6.856) among females after multivariable adjustment.

CONCLUSIONS

After excluding the influence of repeated apnea and hypoxia, simple snoring was still significantly associated with MetS, especially in women. Furthermore, the associations were more obvious for hypertension among males and for abdominal obesity and hyper-TG among females. In addition to OSA, simple snoring also should be valued.

Smartphone-based delivery of oropharyngeal exercises for treatment of snoring: a randomized controlled trial

PURPOSE

Upper airway exercises for snoring treatment can be effective but difficult to administer and monitor. We hypothesized that a brief, relatively simple daily upper airway exercise regimen, administered by a smartphone application, would reduce snoring and encourage compliance.

METHODS

Targeted vowel sounds causing tongue base movements were incorporated into a voice-controlled smartphone game application. Participants with habitual snoring, apnea hypopnea index (AHI) ≤ 14 events/h, and BMI ≤ 32 kg/m² were randomly assigned to perform 15 min of daily gameplay (intervention group) or 5 s of daily voice recording (control group) and to audio record their snoring for 2 nights/week for up to 12 weeks. Sounds above 60 dB were extracted from recordings for snore classification with machine learning support vector machine classifiers.

RESULTS

Sixteen patients (eight in each group) completed the protocol. Groups were similar at baseline in gender distribution (five males, three females), mean BMI (27.5 ± 3.8 vs 27.4 ± 3.8 kg/m²), neck circumference (15.1 ± 1.6 vs 14.7 ± 1.7 in.), Epworth Sleepiness Score (8 ± 3.5 vs 7 ± 4.0), and AHI (9.2 ± 4.0 vs 8.2 ± 3.2 events/h). At 8 weeks, the absolute change in snoring rate (> 60 dB/h) was greater for the intervention group than the control group (- 49.3 ± 55.3 vs - 6.23 ± 23.2; p = 0.037), a 22 and 5.6% reduction, respectively. All bed partners of participants in the intervention group reported reduced snoring volume and frequency, whereas no change was reported for the control group.

CONCLUSIONS

Smartphone application-administered upper airway training reduces objective and subjective snoring measures and improves sleep quality.

TRIAL REGISTRATION

ClinicalTrials.gov ; no.: NCT03264963; URL: www.clinicaltrials.gov.

TranQuill sling snoreplasty for snoring: A single-arm pilot study for safety and effectiveness

OBJECTIVES/HYPOTHESIS

Determine safety and efficacy of the TranQuill Sling Snoreplasty (TSS) (Surgical Specialties Corp., Vancouver, BC, Canada) for the treatment of snoring in adults with benign snoring or mild obstructive sleep apnea.

STUDY DESIGN

Prospective, unblinded, single-center pilot study.

METHODS

From February 2014 to July 2014, 20 adult patients with chronic, disruptive snoring assessed by bed partner were recruited to undergo TSS. Subjects with apnea hypopnea index < 15, minimum oxygen saturation > 85%, and body mass index (BMI) < 32 were included. Outcomes were assessed comparing the results of quality-of-life questionnaires, bed partner-assessed snoring, pain visual analog scales, WatchPAT (Itamar Medical Ltd, Caesarea Ind. Park, Israel) home sleep studies, and flexible endoscopy at baseline and 90-day follow-up.

RESULTS

Thirteen males and seven females were enrolled. Average age was 49.1 (range 31-67) and BMI of 25.8 ± 2.66. TranQuill Sling Snoreplasty significantly reduced snoring symptom scores from 8.70 ± 4.27 to 6.42 ± 4.14, P = 0.012. Snoring visual analog scores demonstrated reduction of 17.8 mm (59.4 mm ± 22.1 to 41.6 mm ± 29.2), P = 0.0184. Thirty-five percent (7/20) of subjects reported complications related to the trial, with no serious adverse events.

CONCLUSION

TranQuill Sling Snoreplasty is a safe therapy that improves snoring symptoms in most adult subjects with benign snoring or mild sleep apnea. Further study is required to better identify patients likely to respond to the therapy.

Comparative Effectiveness of the Different Treatment Modalities for Snoring

Objective

To evaluate what effects treatments of sleep-disordered breathing have on snoring and sleepiness: snoring surgery including osteotomies, mandibular advancement device (MAD), and continuous positive airway pressure (CPAP).

Study Design

Single-institution prospective comparative effectiveness trial.

Setting

University-affiliated secondary care teaching hospital.

Subjects and Methods

We prospectively studied 224 patients presenting with snoring at our department. All patients underwent detailed evaluation, including symptom questionnaires, clinical examination, polysomnography, and drug-induced sleep endoscopy. Based on these results, a treatment was proposed after multidisciplinary consultation. Treatment was evaluated through 4 questionnaires before treatment and 6 weeks and 6 months after. Treatment success was defined as a global snoring visual analog scale score ≤3 at 6 months.

Results

A total of 195 patients complied with full workup and were proposed treatment. The mean age was 46 ± 11 years; the mean body mass index, 27 ± 4; and the median apnea-hypopnea index, 10.0 (interquartile range, 4.7-20.1). After discussion, 116 (59.5%) patients agreed to start treatment (46%, surgery; 26% MAD; 28% CPAP). All symptom scores, including Epworth Sleepiness Scale, decreased significantly for all treatments at 6 weeks and 6 months. Treatment was successful in 67% of the surgery patients, 67% of the MAD group, and 76% of the CPAP group. Only 6.7% reported an unchanged snoring score in the surgery group, compared with 13.6% in the MAD group and 9.6 % in the CPAP group.

Conclusion

Multidisciplinary agreed-on treatment of snoring is effective across the proposed treatments.