Effect of Varying Definitions of Hypopnea on the Diagnosis and Clinical Outcomes of Sleep-Disordered Breathing: A Systematic Review and Meta-Analysis

Large variability in definitions of sleep apnea indices used in clinical studies

STUDY OBJECTIVES

We explored the variability of sleep apnea indices and definitions of obstructive sleep apnea in clinical studies of continuous positive airway pressure.

METHODS

In a systematic review of the long-term clinical effects of continuous positive airway pressure, we noted variability across studies in how sleep apnea was defined. We, thus, sought to quantify the heterogeneity.

RESULTS

Across 57 comparative studies of long-term clinical outcomes of continuous positive airway pressure, only 40% fully and explicitly reported their definitions of apnea and hypopnea. Most studies defined apnea as 100% airflow cessation, but a minority used 90% or even down to 75% thresholds. Almost half of the studies defined hypopnea as ≥ 50% airflow cessation, but the majority used 30% or even 25% thresholds. Similarly, about half of the studies used a 4% desaturation threshold to define oxygen desaturation and about half used a 3% threshold, with 2 studies using both thresholds for different purposes. Randomized trials were no more consistent or better-reported than observational studies. Studies that cited published criteria generally reported definitions that were different from the cited criteria.

CONCLUSIONS

The criteria used to define sleep apnea indices (apnea, hypopnea, and oxygen desaturation) were highly variable, even among studies stating that definitions were based on the same standard criteria. It was often difficult to discern the actual criteria used. The great variability across studies and lack of transparency about their sleep study methods hampers the interpretability and utility of the studies and calls into question whether studies are generalizable from one setting to another.

CITATION

Balk EM, Adam GP, D'Ambrosio CM. Large variability in definitions of sleep apnea indices used in clinical studies. J Clin Sleep Med. 2024;20(3):461-468.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Prognostic Significance of Obstructive Sleep Apnea in a Population of Subjects with Interstitial Lung Diseases

INTRODUCTION

Obstructive sleep apnea (OSA) is often observed in subjects with interstitial lung disease (ILD). It may have a negative impact on the course of ILD, but its prognostic significance in relation to other known indicators of poor outcome is unclear.

METHODS

After a detailed work-up, including overnight unattended type III polygraphy, all subjects newly diagnosed with ILDs referred to our clinics were followed-up for at least 1.5 years or until death or progression of disease [> 10% decline in forced vital capacity (FVC) below baseline]. We analyzed relationships between some prespecified variables of interest, including sleeping results, to establish parameters predictive of progressive course.

RESULTS

Our population consisted of 46 subjects (mean age 59.6 years; males 61%); 23.9% and 41% had idiopathic pulmonary fibrosis and ILD associated with systemic diseases, respectively. Mean baseline forced vital capacity and diffusion capacity of carbon monoxide were 83% and 57% of predicted, respectively. Mean (± SE) Apnea-Hypopnea Index (AHI) was 17 (± 3) events/h. AHI in the ranges 5-14.9, 15-29.9, and ≥ 30 was recorded in 14 (31%), 6 (13%), and 9 (20%) subjects, respectively. Mean distance covered in the 6-MWG walk test (6MWT) was 302 (± 19) m and 26 subjects (57%) showed exertional oxyhemoglobin desaturation. The median follow-up was about 18 months. Multivariate logistic regression analysis showed that exertional desaturation (HR 8.2; 1.8-36.5 95% CI; p = 0.006) and AHI ≥ 30, namely the threshold of severe OSA (HR 7.5; 1.8-30.6; p = 0.005), were the only independent variables related to progressive disease course.

CONCLUSION

We conclude that exertional desaturation and elevated AHI had independent negative prognostic significance in our ILD population.

Sex-specific differences in diagnostic approaches of inpatient sleep testing for obstructive sleep apnea

BACKGROUND

Few studies have investigated sex-specific disparities in inpatient sleep testing. We postulate that women are more likely to have a milder degree of obstructive sleep apnea (OSA) and lower extent of hypoxia on Type III sleep studies versus polysomnography (PSG).

PATIENTS AND METHODS

The Cleveland Clinic Sleep laboratory registry was leveraged to identify all adult inpatient sleep studies performed for OSA. Demographics, comorbidities, and sleep study measures were collected and compared by sex and sleep study type. Logistic regression was used to examine sleep study type predictive of OSA (apnea hypopnea index [AHI; ≥5, ≥15 and ≥ 30]) and hypoxia, (median percentage of sleep time spent at <90% SaO2 [TST<90%,≥ 11%,] adjusted for covariates.

RESULTS

The sample 778 patients had a mean age of 56.1 ± 16.1 years; 44.5% were female and 72.2% Caucasian. At an AHI≥5, women showed an increase odds of OSA (adjusted, OR = 2.04,95%; CI:1.24-3.35, p = 0.005) with Type III sleep study vs PSG compared to men. At an AHI≥15, men had less odds of OSA (adjusted OR = 0.60,95%CI:0.39-0.90,p = 0.015) with Type III sleep study vs PSG compared to women (OR = 1.15,95%CI:0.72-1.85,p = 0.56), with an interaction p-value of 0.040. These results were attenuated when the analysis was restricted using the 3% hypopnea scoring rule. Men and women had higher odds of TST <90 ≥ 11% (OR:2.60,95%CI:1.60-4.21,p=<0.001; OR:3.46,95%CI:1.97-6.05,p < 0.001) with Type III sleep study versus PSG, albeit no sex-interaction was observed.

CONCLUSIONS

These results suggest that sex-specific differences in diagnostic performance of sleep testing type in the inpatient setting should be considered according to level of OSA severity, which are influenced by hypopnea-related desaturation extent.

Desaturation event scoring criteria affect the perceived severity of nocturnal hypoxic load

OBJECTIVES/BACKGROUND

Interest in using blood oxygen desaturations in the diagnostics of sleep apnea has risen in recent years. However, no standardized criteria for desaturation scoring exist which complicates the drawing of solid conclusions from literature.

PATIENTS/METHODS

We investigated how different desaturation scoring criteria affect the severity of nocturnal hypoxic load and the prediction of impaired daytime vigilance in 845 patients. Desaturations were scored based on three features: 1) minimum oxygen saturation drop during the event (2-20%, 1% interval), 2) minimum duration of the event (2-20s, 1s interval), and 3) maximum plateau duration within the event (5-60s, 5s interval), resulting in 4332 different scoring criteria. The hypoxic load was described with oxygen desaturation index (ODI), desaturation severity (DesSev), and desaturation duration (DesDur) parameters. Association between hypoxic load and impaired vigilance was investigated with covariate-adjusted area under curve (AUC) analyses by dividing patients into normal (≤5 lapses) and impaired (≥36 lapses) vigilance groups based on psychomotor vigilance task performance.

RESULTS

The severity of hypoxic load varied greatly between different scoring criteria. For example, median ODI ranged between 0.4 and 12.9 events/h, DesSev 0.01-0.23 %-point, and DesDur 0.3-9.6 %-point when the minimum transient drop criterion of 3% was used and other two features were altered. Overall, the minimum transient drop criterion had the largest effect on parameter values. All models with differently determined parameters predicted impaired vigilance moderately (AUC = 0.722-0.734).

CONCLUSIONS

Desaturation scoring criteria greatly affected the severity of hypoxic load. However, the difference in the prediction of impaired vigilance between different criteria was rather small.

Differences in Symptoms and Severity of Obstructive Sleep Apnea between Black and White Patients

Rationale: Prior work suggests that Black patients have more severe obstructive sleep apnea (OSA) upon clinical presentation. However, the extent to which this may reflect differences in symptoms or other standard measures of OSA risk is unclear. Objectives: We assessed for racial disparities in OSA characteristics at time of initial clinical diagnosis. Methods: Data from 890 newly diagnosed patients with OSA at an urban academic sleep center were included in this analysis. All patients completed a standardized questionnaire on demographics and sleep-related symptoms and underwent laboratory polysomnography. Symptom severity at the time of evaluation was compared across race and sex. Results: Black men were underrepresented in the sleep lab, making up only 15.8% of the cohort and 31.3% of Black participants (P < 0.001). Despite this, Black men had the most severe OSA with a mean apnea hypopnea index of 52.4 ± 39.4 events/hour, compared with 39.0 ± 28.9 in White men, 33.4 ± 32.3 in Black women, and 26.2 ± 23.8 in White women (P < 0.001 for test of homogeneity). Black men also had the greatest burden of OSA symptoms with the highest mean Epworth Sleepiness Scale score (12.2 ± 5.9 versus 9.4 ± 5.2 in White men, 11.2 ± 5.9, in Black women, and 9.8 ± 5.6 in White women; P < 0.001). Compared with White men, Black men were 1.61 (95% CI [1.04-2.51]) times more likely to have witnessed apneas and 1.56 (95% CI [1.00-2.46]) times more likely to have drowsy driving at the time of OSA diagnosis. Conclusions: At the time of clinical diagnosis, Black men have greater disease severity, suggesting delay in diagnosis. Further, the greater burden of classic OSA symptoms suggests the delayed diagnosis of OSA in Black men is not due to atypical presentation. Further research is needed to identify why screening methods for OSA are not equitably implemented in the care of Black men.

Safe use of donated positive airway pressure devices to increase access to treatment for obstructive sleep apnea: a clinical outreach program

Coverage to provide positive airway pressure (PAP) therapy for patients with obstructive sleep apnea (OSA) by the Centers for Medicare and Medicaid Services (CMS) and most private insurers is limited to those patients who meet diagnostic criteria for OSA based on a sleep study. Despite PAP therapy being a covered benefit by most insurers, many patients have high out-of-pocket costs due to copays and deductibles. Also, a subset of patients may be diagnosed per the American Academy of Sleep Medicine (AASM) recommended rule (H3A), while not meeting the diagnosis using the acceptable rule (H4) that their insurer requires.¹ To help patients such as these, our sleep medicine program envisioned and developed a PAP device donation program for patients with diagnosed or suspected OSA. Through our novel initiative, we were able to safely provide patients with donated and refurbished PAP devices at no cost to them. Here we outline the complexity involved in the provision of PAP therapy for patients with OSA and describe our PAP device donation program.

CITATION

Skiba V, McLellan B. Safe use of donated positive airway pressure devices to increase access to treatment for obstructive sleep apnea: a clinical outreach program. J Clin Sleep Med. 2022;18(5):1455-1457.

Arousal-based scoring of obstructive hypopneas

PURPOSE OF REVIEW

Obstructive sleep apnea in adults is diagnosed by an apnea-hypopnea index (AHI) above five (at least five apneas and/or hypopneas per hour of sleep). Though the definition of apneas has remained stable, the scoring criteria for hypopneas has varied throughout the years. There is even more evidence now that scoring respiratory events associated with arousals should be included in the diagnosis of obstructive sleep apnea, as these patients may benefit from treatment.

RECENT FINDINGS

Recent studies, trials and meta-analyses have demonstrated that respiratory events associated with arousal are associated with symptoms, such as poor sleep quality and excessive daytime sleepiness. These arousal-based hypopneas have also been noted to carry a risk of hypertension and other adverse health consequences.

SUMMARY

Requiring a 4% oxygen desaturation for hypopneas may miss patients that may benefit from treatment for obstructive sleep apnea. These patients are typically younger, nonobese, and women as they have been found to have respiratory events causing sleep fragmentation versus significant oxygen desaturation as compared with other populations.

Polysomnographic analysis of respiratory events during sleep in young nonobese Japanese adults without clinical complaints of sleep apnea

STUDY OBJECTIVES

The present study aimed to investigate the occurrence and characteristics of apnea-hypopnea events in young nonobese healthy Japanese participants.

METHODS

One hundred and three young adult participants without sleep complaints (men: 56; women: 47; age: 24.5 ± 3.0 years; body mass index: 20.9 ± 1.8 kg/m²) underwent 2-night polysomnography. Data on the 2nd night were scored according to American Academy of Sleep Medicine criteria version 2.1. The apnea-hypopnea index (AHI) was estimated. The arousal threshold was calculated in participants with AHI ≥ 5 events/h. Apnea-hypopnea events were rescored by 3 other criteria issued by the American Academy of Sleep Medicine (AASM): Chicago criteria in 1999 and recommended and alternative criteria in 2007.

RESULTS

Participants had good sleep characterized by high sleep efficiency (93.2%). Mean AHI of AASM 2.1 recommended criteria was 4.0 ± 5.3 events/h. AHI was significantly higher in men (median [range] = 4.0[.3-35.8] events/h) than in women (1.6 [.1-18.1] events/h). The prevalence rates of AHI ≥ 5 events/h and ≥ 15 events/h were 25.2 and 3.9%, respectively. The arousal threshold was estimated as -7.7 ± 2.6 cm H₂O. AHI was lower for AASM 2007 recommended criteria (.8 [.0-18.2 events/h]) and AASM 2007 alternative (2.0 [.1-32.2] events/h) than for AASM version 2.1 recommended criteria (2.4 [.1-32.9] events/h) and AASM Chicago (4.6 [.1-35.8] events/h). The percentage of participants with AHI ≥ 5 events/h was approximately 2-fold higher with AASM Chicago (44.6%) than with AASM version 2.1 recommended criteria.

CONCLUSIONS

The present study demonstrated that 25% of young nonobese Japanese participants had subclinical obstructive sleep apnea. The presence of frequent airflow limitations may be a risk factor for the development of obstructive sleep apnea in Japanese individuals.

Incidence of hypertension in obstructive sleep apnea using hypopneas defined by 3 percent oxygen desaturation or arousal but not by only 4 percent oxygen desaturation

STUDY OBJECTIVES

This analysis determined ∼5-year incident hypertension rates using the 2017 American College of Cardiology/American Heart Association blood pressure (BP) guidelines in individuals with obstructive sleep apnea (OSA) with hypopneas defined by a ≥ 3% oxygen desaturation or arousal but not by a hypopnea criterion of ≥ 4% oxygen desaturation (4% only).

METHODS

Data were analyzed from participants in the Sleep Heart Health Study exam 2 (n = 1219) who were normotensive (BP ≤ 120/80 mm Hg) at exam 1. The AHI at exam 1 was classified into 4 categories of OSA severity: < 5, 5 ≤ 15, 15 ≤ 30, and ≥ 30 events/h using both the 3% oxygen desaturation or arousal and the 4% only definitions. Three definitions of hypertension-elevated BP (> 120/80 mm Hg), stage 1 (> 130/80 mm Hg), and stage 2 (> 140/90 mm Hg)-were used to determine incidence rates at exam 2.

RESULTS

Five-year follow-up was available for 476 participants classified as having OSA by the 3% oxygen desaturation or arousal criterion but not by the 4% only standard at exam 1. Incident hypertension using American College of Cardiology/American Heart Association-defined BP categories in these discordantly classified individuals were 15% (elevated BP), 15% (stage 1), and 6% (stage 2). Hypertensive medications were used in 4% of participants who were normotensive. The overall incidence rate of at least an elevated BP was 40% (191/476) in those with OSA defined using the 3% oxygen desaturation or arousal criterion but not by the 4% only criterion.

CONCLUSIONS

Use of the 4% only hypopnea definition resulted in the failure to identify a significant number of individuals with OSA who eventually developed hypertension and could have benefited from earlier diagnosis and treatment.

The differential impact of respiratory event scoring criteria on CPAP eligibility in women and men

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is more prevalent and severe in men than women. The American Academy of Sleep Medicine (AASM) offers 2 definitions for scoring hypopneas: "acceptable" = associated with a >4% oxygen desaturation, adopted by Center for Medicare and Medicaid Services (CMS), and "recommended" = associated with a >3% oxygen desaturation and / or an arousal. We hypothesized that CMS versus AASM scoring criteria would differentially impact continuous positive airway pressure (CPAP) eligibility in women and men.

METHODS

We conducted a retrospective review of adult diagnostic in-lab polysomnography (PSG) at an urban academic institution. All PSGs were scored by both CMS and AASM scoring criteria, and an analysis by sex was performed that took into account demographics and other PSG variables.

RESULTS

Of 969 PSGs reviewed, 674 (69.6%) were in women. Women were younger (51.5 vs. 53.3 y/o) and had a higher body mass index (BMI 38.6 kg/m² vs. 33.8 kg/m²) but had similar Epworth Sleepiness Scale scores when compared to men. The odds of an AASM AHI > 5 being missed by CMS scoring in women was 1.89 (95% CI: 1.40-2.53; p<0.001) compared to men and increased to 6.87 among women 40-60 years of age with a BMI≥40 kg/m². After controlling for age, BMI, % REM sleep and mean oxygen saturation, the sex effect remained significant (OR 1.87; 95% CI: 1.36-2.58; p<0.001).

CONCLUSIONS

CMS scoring criteria imparts a sex bias towards women potentially resulting in denial of therapy to symptomatic women with OSA. Larger, prospective cohort studies are needed to confirm these findings.

A comparison of 2 visual methods for classifying obstructive vs central hypopneas

STUDY OBJECTIVES

Rules for classifying apneas as obstructive, central, or mixed are well established. Although hypopneas are given equal weight when calculating the apnea-hypopnea index, classification is not standardized. Visual methods for classifying hypopneas have been proposed by the American Academy of Sleep Medicine and by Randerath et al (Sleep. 2013;36[3]:363-368) but never compared. We evaluated the clinical suitability of the 2 visual methods for classifying hypopneas as central or obstructive.

METHODS

Fifty hypopnea-containing polysomnographic segments were selected from patients with clear obstructive or clear central physiology to serve as standard obstructive or central hypopneas. These 100 hypopnea-containing polysomnographic segments were deidentified, randomized, and scored by 2 groups. We assigned 1 group to use the American Academy of Sleep Medicine criteria and the other the Randerath algorithm. After a washout period, re-randomized hypopnea-containing polysomnographic segments were scored using the alternative method. We determined the accuracy (agreement with standard), interrater (Fleiss's κ), and intrarater agreement (Cohen's κ) for obtained scores.

RESULTS

Accuracy of the 2 methods was similar: 67% vs 69.3% for Randerath et al and the American Academy of Sleep Medicine, respectively. Cohen's κ was 0.01-0.75, showing that some raters scored similarly using the 2 methods, while others scored them markedly differently. Fleiss's κ for the American Academy of Sleep Medicine algorithm was 0.32 (95% confidence interval, 0.29-0.36) and for the Randerath algorithm was 0.27 (95% confidence interval, 0.23-0.30).

CONCLUSIONS

More work is needed to discover a noninvasive way to accurately characterize hypopneas. Studies like ours may lay the foundation for discovering the full spectrum of physiologic consequences of obstructive sleep apnea and central sleep apnea.

Long-term stability of results following surgery for obstructive sleep apnea (OSA)

PURPOSE

Although upper airway surgery in selected patients with obstructive sleep apnea (OSA) has been shown to be beneficial, its long-term effects have been questioned. The main objective was to evaluate whether results following surgery remain stable over time, both in objective and subjective terms. As a secondary aim, such stability was also measured in relation with the type of surgery performed.

METHODS

This work constitutes a retrospective study of OSA adult patients subjected to the following surgical procedures: different types of pharyngoplasties, tongue-base surgery, partial epiglottectomy or hyoid suspension. Those who exclusively underwent tonsillectomy or nasal surgery were excluded. Before surgery, a sleep study, and an assessment of the patients' sleepiness and quality of life were performed, which were repeated at 8, 34, and 48 months after surgery. A total of 153 patients was included.

RESULTS

Following surgery, the apnea-hypopnea index decreased from 34.84/h to 14.54/h and did not vary more than one point in subsequent controls (p = 0.01). The oxygen desaturation index changed from 31.02/h to 14.0/h and remained stable in the second (15.34/h) and third (11.43/h) controls (p = 0.01). Parameters measuring sleepiness and well-being demonstrated the maintenance of long-term benefits. New pharyngoplasties were observed to be more stable than classic pharyngoplasties in the long term (p = 0.04). Single-level surgeries were found to be more stable than multilevel surgeries, although a statistically significant difference was not observed (p = 0.07).

CONCLUSION

The benefits obtained remained stable in the long term. In our sample, modern pharyngoplasty techniques showed superiority over the classic ones regarding long-term stability.

The Association of Sleep Apnea and Cardiorespiratory Fitness With Long-Term Major Cardiovascular Events

OBJECTIVE

To determine the risk of long-term major adverse cardiovascular events (MACE) when sleep-disordered breathing (SDB) and decreased cardiorespiratory fitness (CRF) co-occur.

METHODS

We included consecutive patients who underwent symptom-limited cardiopulmonary exercise tests between January 1, 2005, and January 1, 2010, followed by first-time diagnostic polysomnography within 6 months. Patients were stratified based on the presence of moderate-to-severe SDB (apnea/hypopnea index ≥15 per hour) and decreased CRF defined as <70% predicted peak oxygen consumption (VO₂). Long-term MACE was a composite outcome of myocardial infarction (MI), coronary artery bypass graft (CABG), percutaneous coronary intervention (PCI), stroke or transient ischemic attack (TIA), and death, assessed until May 21, 2018. Cox-proportional hazard models were adjusted for factors known to influence CRF and MACE.

RESULTS

Of 498 included patients (60±13 years, 28.1% female), 175 (35%) had MACE (MI=17, PCI=14, CABG=13, stroke=20, TIA=12, deaths=99) at a median follow-up of 8.7 years (interquartile range=6.5 to 10.3 years). After adjusting for age, sex, beta blockers, systemic hypertension, diabetes mellitus, coronary artery disease, cardiac arrhythmia, chronic obstructive pulmonary disease, smoking, and use of positive airway pressure (PAP), decreased CRF alone (hazard ratio [HR]=1.91, 95% confidence interval [CI], 1.15 to 3.18; P=.01), but not SDB alone (HR=1.26, 95% CI, 0.75 to 2.13, P=.39) was associated with increased risk of MACE. Those with SDB and decreased CRF had greater risk of MACE compared with patients with decreased CRF alone (HR=1.85; 95% CI, 1.21 to 2.84; P<.005) after accounting for these confounders. The risk of MACE was attenuated in those with reduced CRF alone after additionally adjusting for adequate adherence to PAP (HR=1.59; 95% CI, 0.77 to 3.31; P=.21).

CONCLUSION

The incidence of MACE, especially mortality, was high in this sample. Moderate-to-severe SDB with concurrent decreased CRF was associated with higher risk of MACE than decreased CRF alone. These results highlight the importance of possibly including CRF in the risk assessment of patients with SDB and, conversely, that of screening for SDB in patients with low peak VO₂.

Dental sleep medicine: Time to incorporate sleep apnoea education in the dental curriculum

Dental sleep medicine is a discipline that includes conditions such as sleep breathing disorders (eg snoring and sleep apnoea), sleep bruxism, orofacial pain and sleep-related complaints, and to some extent gastro-oesophageal reflux disorder and/or insomnia. Obstructive sleep apnoea (OSA) is a life-threatening condition that dentists need to identify and manage when indicated in order to increase patient well-being and to be taken in consideration in the dental curriculum. The main objective of this paper is to highlight the relevance of dental sleep medicine in the context of dental education, and to discuss potential educational content for integration in the dental curriculum with a focus on OSA, a condition that is not yet integrated in many dental training curricula around the world.

Concordance between current American Academy of Sleep Medicine and Centers for Medicare and Medicare scoring criteria for obstructive sleep apnea in hospitalized persons with traumatic brain injury: a VA TBI Model System study

STUDY OBJECTIVES

The objective of this study was to compare obstructive sleep apnea (OSA), demographic, and traumatic brain injury (TBI) characteristics across the American Academy of Sleep Medicine (AASM) and Centers for Medicare and Medicare (CMS) scoring rules in moderate to severe TBI undergoing inpatient neurorehabilitation.

METHODS

This is a secondary analysis from a prospective clinical trial of sleep apnea at 6 TBI Model System study sites (n = 248). Scoring was completed by a centralized center using both the AASM and CMS criteria for OSA. Hospitalization and injury characteristics were abstracted from the medical record, and demographics were obtained by interview by trained research assistants using TBI Model System standard procedures.

RESULTS

OSA was prevalent using the AASM (66%) and CMS (41.5%) criteria with moderate to strong agreement (weighted κ = 0.64; 95% confidence interval = 0.58-0.70). Significant differences were observed for participants meeting AASM and CMS criteria (concordant group) compared with those meeting criteria for AASM but not CMS (discordant group). At an apnea-hypopnea index ≥ 5 events/h, the discordant group (n = 61) had lower Emergency Department Glasgow Coma Scale Scores consistent with greater injury severity (median, 5 vs 13; P = .0050), younger age (median, 38 vs 58; P < .0001), and lower body mass index (median, 22.1 vs 24.8; P = .0007) compared with the concordant group (n = 103). At an apnea-hypopnea index ≥ 15 events/h, female sex but no other differences were noted, possibly because of the smaller sample size.

CONCLUSIONS

The underestimation of sleep apnea using CMS criteria is consistent with prior literature; however, this is the first study to report the impact of the criteria in persons with moderate to severe TBI during a critical stage of neural recovery. Management of comorbidities in TBI has become an increasing focus for optimizing TBI outcomes. Given the chronic morbidity after moderate to severe TBI, the impact of CMS policy for OSA diagnosis for persons with chronic disability and young age are considerable.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Comparison of Sleep Apnea Assessment Strategies to Maximize TBI Rehabilitation Participation and Outcome; Identifier: NCT03033901.

Obstructive Sleep Apnea in Neurodegenerative Disorders: Current Evidence in Support of Benefit from Sleep Apnea Treatment

Obstructive sleep apnea (OSA) is a prevalent disorder characterized by recurrent upper airway obstruction during sleep resulting in intermittent hypoxemia and sleep fragmentation. Research has recently increasingly focused on the impact of OSA on the brain's structure and function, in particular as this relates to neurodegenerative diseases. This article reviews the links between OSA and neurodegenerative disease, focusing on Parkinson's disease, including proposed pathogenic mechanisms and current knowledge on the effects of treatment.

Frequency and outcomes of primary central sleep apnea in a population-based study

BACKGROUND

Primary central sleep apnea (PCSA) is believed to be rare and data regarding its prevalence and long-term outcomes are sparse. We used the Rochester Epidemiology Project (REP) resources to identify all Olmsted County, Minnesota, residents with an incident diagnosis of PCSA and their clinical outcomes.

METHODS

We searched the REP database for all residents with polysomnography (PSG)-confirmed diagnoses of central sleep apnea (CSA) between 2007 and 2015. From these, we reviewed the PSGs and medical records to find those who had PCSA based upon accepted diagnostic criteria. Data based on detailed review of the medical records, including all clinical notes and tests were recorded for analysis.

RESULTS

Of 650 patients identified with CSA, 25 (3.8%; 23 male) had PCSA, which was severe in most patients (n = 16, 64%). Of those, 23 (92%) patients were prescribed and 18/23 (78.2%) adherent to positive airway pressure therapy. Median duration of follow-up was 4.4 years (IQR:4.2). Four (16%) patients were subsequently diagnosed with cardiac arrhythmias, one (4%) with unstable angina, two (8%) with heart failure, five (20%) with mild cognitive impairment (MCI)/dementia and two (8%) with depression. Six (25%) patients died (median time to death = 5 years; IQR:4.8), three of whom had Lewy body dementia.

CONCLUSIONS

In this population-based study, PCSA was rare and when present, was severe in a majority of patients. The mortality rate was high. Most frequently observed disorders during follow-up were mild cognitive impairment (MCI)/dementia followed by cardiac arrhythmias; it is possible that these entities were present and not recognized prior to the diagnosis of PCSA.

[Sleep-related breathing disorders in adults: diagnosis, consequences and comorbidities]

Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a collapse of the upper airways leading to a decrease (hypopneas) or interruption of air flow (apneas). Since its identification, only forty years ago, definitions, diagnostic techniques have evolved, the consequences of this syndrome have been widely studied but establishing it as an independent cardiovascular (CV) risk factor has come up against the existence of many confounding factors, such as obesity, high blood pressure (hypertension)… Paraclinical diagnosis is based on the results of poly(somno)graphy. Recommendations on measurement techniques and scoring are regularly published, evolving in parallel with technological progress, with the aim of standardizing and ensuring the reliability of the diagnosis. At the same time, large cohort studies were set up in the 1990s, allowing for transversal and longitudinal follow-up of thousands of patients. Finally, the pathophysiological mechanisms of the consequences of SAHOS were explored. OSA has been shown to be responsible for a particularly high accidental risk due to sleep fragmentation induced by abnormal respiratory events. It has been possible to establish an independent statistical relationship between SAHOS and CV diseases, metabolic disorders and more recently cancer, mainly explained by intermittent hypoxia. OSAHOS is a frequent disease, diagnosed on the basis of clinical signs and poly(somno)graphy, now established as an independent risk factor for morbidity and mortality (accidental and CV).

Critical Issues in Dental and Medical Management of Obstructive Sleep Apnea

This critical review focuses on obstructive sleep apnea (OSA) and its management from a dental medicine perspective. OSA is characterized by ≥10-s cessation of breathing (apnea) or reduction in airflow (hypopnea) ≥5 times per hour with a drop in oxygen and/or rise in carbon dioxide. It can be associated with sleepiness and fatigue, impaired mood and cognition, cardiometabolic complications, and risk for transportation and work accidents. Although sleep apnea is diagnosed by a sleep physician, its management is interdisciplinary. The dentist’s role includes 1) screening patients for OSA risk factors (e.g., retrognathia, high arched palate, enlarged tonsils or tongue, enlarged tori, high Mallampati score, poor sleep, supine sleep position, obesity, hypertension, morning headache or orofacial pain, bruxism); 2) referring to an appropriate health professional as indicated; and 3) providing oral appliance therapy followed by regular dental and sleep medical follow-up. In addition to the device features and provider expertise, anatomic, behavioral, demographic, and neurophysiologic characteristics can influence oral appliance effectiveness in managing OSA. Therefore, OSA treatment should be tailored to each patient individually. This review highlights some of the putative action mechanisms related to oral appliance effectiveness and proposes future research directions.

Longitudinal effect of nocturnal R-R intervals changes on cardiovascular outcome in a community-based cohort

RATIONALE

Sleep-disordered breathing (SDB) is strongly linked to adverse cardiovascular outcomes (cardiovascular diseases (CVD)). Whether heart rate changes measured by nocturnal R-R interval (RRI) dips (RRI dip index (RRDI)) adversely affect the CVD outcomes is unknown.

OBJECTIVES

To test whether nocturnal RRDI predicts CVD incidence and mortality in the Wisconsin Sleep Cohort study (WSCS), independent of the known effects of SDB on beat-to-beat variability.

METHODS

The study analysed electrocardiograph obtained from polysomnography study to assess the nocturnal total RRDI (the number of RRI dips divided by the total recording time) and sleep RRDI (the number of RRI dips divided by total sleep time). A composite CVD risk as a function of total and sleep RRDI was estimated by Cox proportional hazards in the WSCS.

RESULTS

The study sample consisted of 569 participants from the WSCS with no prior CVD at baseline were followed up for up to 15 years. Nocturnal total RRDI (10-unit change) was associated with composite CVD event(s) (HR, 1.24 per 10-unit increment in RRDI (95% CI 1.10 to 1.39), p<0.001). After adjusting for demographic factors (age 58±8 years old; 53% male; and body mass index 31±7 kg/m²), and apnoea-hypopnoea index (AHI 4%), individuals with highest total nocturnal RRDI category (≥28 vs<15 dips/hour) had a significant HR for increased incidence of CVD and mortality of 7.4(95% CI 1.97 to 27.7), p=0.003). Sleep RRDI was significantly associated with new-onset CVD event(s) (HR, 1.21 per 10-unit increment in RRDI (95% CI 1.09 to 1.35), p<0.001) which remained significant after adjusting for demographic factors, AHI 4%, hypoxemia and other comorbidities.

CONCLUSION

Increased nocturnal RRDI predicts cardiovascular mortality and morbidity, independent of the known effects of SDB on beat-to-beat variability. The frequency of RRDI is higher in men than in women, and is significantly associated with new-onset CVD event(s) in men but not in women.