Sleep-disordered breathing in the usual lifestyle setting as detected with home monitoring in a population of working men in Japan

Polysomnographic features prior to dream enactment behaviors in isolated rapid eye movement sleep behavior disorder

OBJECTIVE

This study aimed to identify electroencephalogram correlates of dream enactment behaviors (DEBs) and elucidate their cortical dynamics in patients with isolated/idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD).

METHODS

This cross-sectional study included 15 patients with iRBD. Two REM sleep periods in routine polysomnography were compared: the 60 s preceding the DEBs ("pre-representative behavior" [preR]), and the 60 s with the least submental electromyogram activity ("background" [BG]). Six EEG frequency bands and electrooculogram were analyzed; power spectra, coherence and phase-locking values in four 15-s periods were examined to assess trends. These indices were also compared between preR and BG.

RESULTS

Compared with BG, significantly higher delta power in the F3 channel and gamma power in the F4 and O2 channels were observed during preR. For functional connectivity, the widespread beta-band connectivity was significantly increased during preR than BG.

CONCLUSION

Before notable REM sleep behaviors, uneven distributed higher EEG spectral power in both very low and high frequencies, and increased wide-range beta band functional connectivity, were observed over 60 s, suggesting cortical correlates to subsequent DEBs.

SIGNIFICANCE

This study may shed light on the pathological mechanisms underlies RBD through the routine vPSG analysis, leading to detection of DEBs.

The prevalence of obstructive sleep apnea in Japanese asthma patients

BACKGROUND

Obstructive sleep apnea (OSA) occurs more commonly in asthma patients than in the general population because these conditions share some comorbidities. In Japan, the prevalence of OSA in the general population is reported to be approximately 20%; however, few reports have described the prevalence of OSA in asthma patients. Furthermore, the characteristics of Japanese patients with OSA and asthma are not clear.

METHODS

Adult asthma patients were recruited from the outpatient departments of our institution between August 31, 2017, and March 31, 2019. In all included patients, the presence and severity of OSA were evaluated by the Epworth Sleepiness Scale (ESS) and a home sleep test (HST) using portable polysomnography (PSG). The rate of coexisting OSA in asthma patients and the characteristics of those patients according to the severity of OSA were investigated.

RESULTS

Fifty-three patients were included. OSA was detected in 36 (67.9%) patients (mild, n = 15; moderate, n = 14; and severe, n = 7). Patients with OSA had significantly higher body mass index, Brinkman index, apnea-hypopnea index (AHI), and 3% oxygen desaturation index (ODI) values in comparison to those without OSA, while the percentage of the predicted value of forced vital capacity (%FVC) and lowest SpO2 levels were significantly lower. As the severity of OSA increased, age, brain natriuretic peptide level, AHI, and 3%ODI increased, and in contrast, FVC, %FVC, forced expiratory volume in one second (FEV1), percentage of the predicted value of FEV1 (%FEV1), Epworth Sleepiness Scale (ESS), 3%ODI, and lowest SpO2 levels decreased. In particular, the fact that the ESS value was inversely correlated with the severity of OSA in our patients was different from the general characteristics of OSA. Moreover, the AHI value was negatively correlated with FVC, %FVC, FEV1, and %FEV1. BMI was the only independent factor for the presence of OSA, and for asthma severity (FEV1, % of predicted), there was a weak correlation with smoking history.

CONCLUSIONS

This is the first report to investigate the prevalence of OSA in Japanese asthma patients, using an HST. This study suggests that an HST should be performed in addition to the sleep interview for asthma patients with refractory disease, a low pulmonary function, advanced age, and high BMI because the more severe the OSA, the lower the ESS value may be.

Educating patients with upper limb dysfunction on self-adjustment of the CPAP/NPPV mask: A case series

We share our experiences of instructing three patients with severe upper limb dysfunction on how to self-adjust CPAP/NPPV masks. In Case 1, we simplified the procedure by suturing a part of the headband as the left forearm was amputated. In Case 2, the patient had congenitally short limbs with short stature; thus, we provided an additional belt to the headband to maintain the headband's configuration while wearing the mask. In Case 3, the patient had left hemiplegia due to stroke and, repetitive coaching was conducted during the recovery phase rehabilitation program. Difficulties with self-adjusting NPPV/CPAP masks can occur whenever there is limited hand mobility above the head, including upper limb dysfunction. Simplifying procedures and providing sufficient time for instruction could help achieve independence. There have been no previous reports describing similar training details. We believe that sharing this knowledge will be helpful to both patients and healthcare professionals.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

Multiple-access versus telemedicine home-based sleep apnea testing for obstructive sleep apnea (OSA) diagnosis: a cost-minimization study

PURPOSE

The aim of the present study was to compare two clinical pathways: the multiple-access outpatient pathway versus the telemedicine pathway.

METHODS

The multiple-access outpatient pathway and the telemedicine pathway were both performed with WatchPAT and implemented in a real-life healthcare scenario, adopting a cost-minimization approach. A cost-minimization analysis was undertaken to assess the economic impact of the two alternatives. The cost analyses were performed in euros for the year 2021 adopting the patient, the hospital, and the societal perspectives. Given the chosen perspectives, direct medical costs, direct nonmedical costs, and indirect costs were considered. In addition, a univariate sensitivity analysis was conducted.

RESULTS

From a hospital perspective, the telemedicine approach was estimated to cost €49 more than the multiple-access alternative. Considering the patient perspective, the telemedicine approach was estimated to cost €167 less than the multiple-access pathway. Considering the societal perspective, the telemedicine approach is estimated to cost €119 less than the multiple-access pathway.

CONCLUSION

The adoption of telemedicine home sleep apnea testing could improve the efficiency of the healthcare processes if considering the direct and indirect costs incurred by patients and not only by healthcare providers.

Irregular sleep and all-cause mortality: A large prospective cohort study

OBJECTIVES

Previous studies using objective parameters have shown that irregular sleep is associated with the disease incidence, progression, or mortality. This study aimed to determine the association between subjective sleep duration and sleep regularity, with mortality in a large population.

METHODS

Participants were from the Japan Multi-Institutional Collaborative Cohort study. We obtained information from each participant on sleep duration, sleep regularity, and demographics and overall lifestyle using self-administered questionnaires. We defined sleep regularity according to participants' subjective assessment of sleep/wake time regularity. Participants (n = 81,382, mean age: 58.1 ± 9.1years, males: 44.2%) were classified into 6 groups according to sleep duration and sleep regularity. Hazard ratios (HR) for time-to-event of death were calculated using the Cox proportional hazards model.

RESULTS

The mean follow-up period was 9.1 years and the mean sleep duration was 6.6 h/day. Irregular sleep significantly increased the risk of all-cause mortality in all models compared with regular sleep (HR 1.30, 95% confidence interval; CI, 1.18-1.44), regardless of sleep duration. Multivariable analysis of the 6 groups by sleep pattern (sleep regularity and duration) showed irregular sleep and sleep durations of <6 h/day, 6 to <8 h/day, or ≥8 h/day were associated with a 1.2-1.5-fold increases in mortality, compared to regular sleep and sleep duration of 6 to <8 h/day.

CONCLUSIONS

Our study shows an association between sleep irregularity and all-cause mortality in a large Japanese population. Our findings provide further confirmation of the need to consider not only sleep duration, but also the regularity aspect of sleep schedules.

Obstructive Sleep Apnoea Severity Is Negatively Associated with Depressive Symptoms: A Cross-Sectional Survey of Outpatients with Suspected Obstructive Sleep Apnoea in Japan

Background: Multiple clinical departments are involved in the provision of obstructive sleep apnoea (OSA) therapy in Japan. Inconsistent results regarding the association between depression and OSA have been reported. Methods: This cross-sectional survey compared newly diagnosed OSA patients at two outpatient sleep apnoea units in Shiga Prefecture, Japan: one associated with the psychiatry department (n = 583), and the other with the otolaryngology department (n = 450). Results: The unit associated with the psychiatry department had more patients referred by psychiatrists than that with the otolaryngology department (11% vs. 3% p < 0.05). Sleepiness, insomnia, and depression were assessed using the Epworth Sleepiness Scale (ESS), Athens Insomnia Scale (AIS), and Patient Health Questionnaire-9 (PHQ-9), respectively. The ESS, AIS, and PHQ-9 scores were higher in the sleep unit in the psychiatry department (p < 0.001 each). Snoring and moderate to severe OSA were more prevalent in the unit attached to the otolaryngology department (p < 0.001 each). Patients with moderate to severe OSA had lower PHQ-9 scores than those with no to mild OSA (OR: 0.96, 95% CI: 0.92−1.00, p = 0.042). Conclusion: Patients with sleepiness, insomnia, and depressive symptoms were more likely to attend a sleep outpatient unit associated with a psychiatry department, whereas those with snoring and sleep apnoea attended that associated with an otolaryngology department. OSA severity was negatively associated with depressive symptoms.

Work Habit-Related Sleep Debt; Insights From Factor Identification Analysis of Actigraphy Data

The present study investigates the factors of “Weekday sleep debt (WSD)” by comparing activity data collected from persons with and without WSD. Since it has been reported that the amount of sleep debt as well the difference between the social clock and the biological clock is associated with WSD, specifying the factors of WSD other than chronotype may contribute to sleep debt prevention. We recruited 324 healthy male employees working at the same company and collected their 1-week wrist actigraphy data and answers to questionnaires. Because 106 participants were excluded due to measurement failure of the actigraphy data, the remaining 218 participants were included in the analysis. All participants were classified into WSD or non-WSD groups, in which persons had WDS if the difference between their weekend sleep duration and the mean weekday sleep duration was more than 120 min. We evaluated multiple measurements derived from the collected actigraphy data and trained a classifier that predicts the presence of WSD using these measurements. A support vector machine (SVM) was adopted as the classifier. In addition, to evaluate the contribution of each indicator to WSD, permutation feature importance was calculated based on the trained classifier. Our analysis results showed significant importance of the following three out of the tested 32 factors: (1) WSD was significantly related to persons with evening tendency. (2) Daily activity rhythms and sleep were less stable in the WSD group than in the non-WSD group. (3) A specific day of the week had the highest importance in our data, suggesting that work habit contributes to WSD. These findings indicate some WSD factors: evening chronotype, instability of the daily activity rhythm, and differences in work habits on the specific day of the week. Thus, it is necessary to evaluate the rhythms of diurnal activities as well as sleep conditions to identify the WSD factors. In particular, the diurnal activity rhythm influences WSD. It is suggested that proper management of activity rhythm may contribute to the prevention of sleep debt.

Clinical Usefulness of New R-R Interval Analysis Using the Wearable Heart Rate Sensor WHS-1 to Identify Obstructive Sleep Apnea: OSA and RRI Analysis Using a Wearable Heartbeat Sensor

Obstructive sleep apnea (OSA) is highly associated with cardiovascular diseases, but most patients remain undiagnosed. Cyclic variation of heart rate (CVHR) occurs during the night, and R-R interval (RRI) analysis using a Holter electrocardiogram has been reported to be useful in screening for OSA. We investigated the usefulness of RRI analysis to identify OSA using the wearable heart rate sensor WHS-1 and newly developed algorithm. WHS-1 and polysomnography simultaneously applied to 30 cases of OSA. By using the RRI averages calculated for each time series, tachycardia with CVHR was identified. The ratio of integrated RRIs determined by integrated RRIs during CVHR and over all sleep time were calculated by our newly developed method. The patient was diagnosed as OSA according to the predetermined criteria. It correlated with the apnea hypopnea index and 3% oxygen desaturation index. In the multivariate analysis, it was extracted as a factor defining the apnea hypopnea index (r = 0.663, p = 0.003) and 3% oxygen saturation index (r = 0.637, p = 0.008). Twenty-five patients could be identified as OSA. We developed the RRI analysis using the wearable heart rate sensor WHS-1 and a new algorithm, which may become an expeditious and cost-effective screening tool for identifying OSA.

Cluster analysis identifies a pathophysiologically distinct subpopulation with increased serum leptin levels and severe obstructive sleep apnea

PURPOSE

To investigate the different pathophysiologies of obstructive sleep apnea (OSA) phenotypes using cluster analysis. Differences between leptin/adiponectin levels in the resulting OSA phenotypes were also examined.

METHODS

In total, 1057 OSA patients were selected, and a retrospective survey of clinical records, polysomnography results, and blood gas data was conducted. Patients were grouped into four clusters by their OSA severity, PaCO2, body mass index (BMI), and sleepiness. A k-means cluster analysis was performed, resulting in a division into four subpopulations. The Tukey or Games-Howell tests were used for intergroup comparisons.

RESULTS

Among the 20 clinical OSA items, four common factors (Epworth Sleepiness Scale [ESS], BMI, Apnea-Hypopnea Index [AHI], and PaCO2) were extracted by principal component analysis, and a cluster analysis was performed using the k-means method, resulting in four distinct phenotypes. The Clusters 1 (middle age, symptomatic severe OSA) and 4 (young, obese, symptomatic very severe OSA) exhibited high leptin levels. C-reactive protein levels were also elevated in Cluster 4, indicating a different pathophysiological background. No apparent differences between clusters were observed regarding adiponectin/leptin ratios and adiponectin levels. Classification into groups based on phenotype showed that Epworth Sleepiness Scale [ESS] score and disease severity were not correlated, suggesting that sleepiness is affected by multiple elements.

CONCLUSIONS

The existence of multiple clinical phenotypes suggests that different pathophysiological backgrounds exist such as systemic inflammation and metabolic disorder. This classification may be used to determine the efficacy of continuous positive airway pressure treatment that cannot be determined by the AHI.

Validation of Oximetry for Diagnosing Obstructive Sleep Apnea in a Clinical Setting

A large epidemiological study using oximetry to analyze obstructive sleep apnea (OSA) and metabolic comorbidities was performed in Japan; however, reliability and validity of oximetry in the Japanese population remains poorly understood. In this study, oximetry data from the epidemiological study were compared with data from clinically performed polysomnography (PSG) and out-of-center sleep testing (OCST) in epidemiological study participants who later attended our outpatient units. The oxygen desaturation index (ODI) from oximetry showed a moderate positive relationship (correlation coefficient r = 0.561, p < 0.001) with apnea/hypopnea data from PSG/OCST. The area under the receiver operating characteristic curve showed moderate accuracy of this method in the detection of moderate-to-severe or severe OSA. However, the optimal ODI thresholds to detect moderate-to-severe OSA and severe OSA were the same (ODI > 20.1). Oximetry may be a useful tool for screening moderate-to-severe or severe sleep apnea. However, it may be difficult to set an appropriate threshold to distinguish between moderate and severe sleep apnea by oximetry alone.

Cost-Effectiveness of Obstructive Sleep Apnea Screening and Treatment Before Catheter Ablation for Symptomatic Atrial Fibrillation

Background: Although management of obstructive sleep apnea (OSA) has been recommended to improve outcomes of catheter ablation (CA) in patients with symptomatic atrial fibrillation (AF), the most cost-effective way of preprocedural OSA screening is undetermined. This study assessed the cost-effectiveness of OSA management before CA for symptomatic AF.

Methods and Results: A Markov model was developed to assess the cost-effectiveness of 3 OSA detection strategies before CA: no screening; Type 3 portable monitor (PM)-guided screening; and polysomnography (PSG)-guided screening. The target population consisted of a hypothetical cohort of patients aged 65 years with symptomatic AF, with 50% prevalence of OSA. We used a 5-year horizon, with sensitivity analyses for significant variables and scenario analyses for lower and higher OSA prevalence (30% and 70%, respectively). In the base-case, both types of OSA screening were dominant (less costly and more effective) relative to no screening. Although PSG-guided management was more effective than PM-guided management, it was more costly and therefore did not show clear benefit. These findings were replicated in cohorts with lower and higher OSA risks.

Conclusions: OSA screening before CA is cost-effective in patients with symptomatic AF, with PM screening being the most cost-effective. Physicians should consider OSA management using this simple tool in the decision making for treatment of symptomatic AF.

Obstructive sleep apnea screening by heart rate variability-based apnea/normal respiration discriminant model

OBJECTIVE

Obstructive sleep apnea (OSA) is a common sleep disorder; however, most patients are undiagnosed and untreated because it is difficult for patients themselves to notice OSA in daily living. Polysomnography (PSG), which is the gold standard test for sleep disorder diagnosis, cannot be performed in many hospitals. This fact motivates us to develop a simple system for screening OSA at home.

APPROACH

The autonomic nervous system changes during apnea, and such changes affect heart rate variability (HRV). This work develops a new apnea screening method based on HRV analysis and machine learning technologies. An apnea/normal respiration (A/N) discriminant model is built for respiration condition estimation for every heart rate measurement, and an apnea/sleep ratio is introduced for final diagnosis. A random forest is adopted for the A/N discriminant model construction, which is trained with the PhysioNet apnea-ECG database.

MAIN RESULTS

The screening performance of the proposed method was evaluated by applying it to clinical PSG data. Sensitivity and specificity achieved 76% and 92%, respectively, which are comparable to existing portable sleep monitoring devices used in sleep laboratories.

SIGNIFICANCE

Since the proposed OSA screening method can be used more easily than existing devices, it will contribute to OSA treatment.

Estimation of the global prevalence and burden of obstructive sleep apnoea: a literature-based analysis

BACKGROUND

There is a scarcity of published data on the global prevalence of obstructive sleep apnoea, a disorder associated with major neurocognitive and cardiovascular sequelae. We used publicly available data and contacted key opinion leaders to estimate the global prevalence of obstructive sleep apnoea.

METHODS

We searched PubMed and Embase to identify published studies reporting the prevalence of obstructive sleep apnoea based on objective testing methods. A conversion algorithm was created for studies that did not use the American Academy of Sleep Medicine (AASM) 2012 scoring criteria to identify obstructive sleep apnoea, allowing determination of an equivalent apnoea-hypopnoea index (AHI) for publications that used different criteria. The presence of symptoms was not specifically analysed because of scarce information about symptoms in the reference studies and population data. Prevalence estimates for obstructive sleep apnoea across studies using different diagnostic criteria were standardised with a newly developed algorithm. Countries without obstructive sleep apnoea prevalence data were matched to a similar country with available prevalence data; population similarity was based on the population body-mass index, race, and geographical proximity. The primary outcome was prevalence of obstructive sleep apnoea based on AASM 2012 diagnostic criteria in individuals aged 30-69 years (as this age group generally had available data in the published studies and related to information from the UN for all countries).

FINDINGS

Reliable prevalence data for obstructive sleep apnoea were available for 16 countries, from 17 studies. Using AASM 2012 diagnostic criteria and AHI threshold values of five or more events per h and 15 or more events per h, we estimated that 936 million (95% CI 903-970) adults aged 30-69 years (men and women) have mild to severe obstructive sleep apnoea and 425 million (399-450) adults aged 30-69 years have moderate to severe obstructive sleep apnoea globally. The number of affected individuals was highest in China, followed by the USA, Brazil, and India.

INTERPRETATION

To our knowledge, this is the first study to report global prevalence of obstructive sleep apnoea; with almost 1 billion people affected, and with prevalence exceeding 50% in some countries, effective diagnostic and treatment strategies are needed to minimise the negative health impacts and to maximise cost-effectiveness.

FUNDING

ResMed.

Investigation of Obstructive Sleep Apnea Using Portable Monitors and Health Check Data in Japanese Drivers

AIMS

The identification and appropriate management of commercial motor vehicle (CMV) drivers with unrecognized obstructive sleep apnea (OSA) is a major public health concern and priority; OSA among drivers has not been fully investigated in Japan, and a better understanding of this undiagnosed disease is warranted. Therefore, we evaluated the prevalence of OSA and the factors related to apnea-hypopnea index (AHI) in Japanese CMV drivers.

METHODS

This retrospective study included 1309 Japanese CMV drivers aged 40-69 years. All the subjects received type Ⅳ portable sleep monitors (PMs) with Epworth Sleepiness Scale (ESS) and a periodic health check including anthropometrical and laboratory measurements, and a questionnaire of medical history, smoking status, and life style, following which variables related to AHI were analyzed.

RESULTS

Of all the subjects, 23.9% had moderate to severe OSA (AHI ≥15). Age, body mass index (BMI), LogeHbA1c and diastolic blood pressure (DBP) showed significance with AHI in 1309 subjects. The following factors were found to have significant odds ratio (OR) for AHI of ≥15 in 1309 subjects: age, ESS, DBP, and LogeHbA1c.

CONCLUSION

Notably, drivers with undiagnosed OSA exist. In these subjects, AHI was related to obesity, hypertension, and diabetes. For the early diagnosis and intervention of OSA, BMI, blood pressure, and HbA1c measurements may be helpful, particularly for drivers. Furthermore, when performing an objective assessment of the suspected OSA, evaluating these parameters during routine medical check-ups may be useful and feasible in the detection of drivers with latent OSA.

Sleep: important considerations for the prevention of cardiovascular disease

PURPOSE OF REVIEW

Sleep plays many roles in maintenance of cardiovascular health. This review summarizes the literature across several areas of sleep and sleep disorders in relation to cardiometabolic disease risk factors.

RECENT FINDINGS

Insufficient sleep duration is prevalent in the population and is associated with weight gain and obesity, inflammation, cardiovascular disease, diabetes, and mortality. Insomnia is also highly present and represents an important risk factor for cardiovascular disease, especially when accompanied by short sleep duration. Sleep apnea is a well-characterized risk factor for cardiometabolic disease and cardiovascular mortality. Other issues are relevant as well. For example, sleep disorders in pediatric populations may convey cardiovascular risks. Also, sleep may play an important role in cardiovascular health disparities.

SUMMARY

Sleep and sleep disorders are implicated in cardiometabolic disease risk. This review addresses these and other issues, concluding with recommendations for research and clinical practice.

Sensitivity and specificity of Frontal Assessment Battery in newly diagnosed and untreated obstructive sleep apnea patients

BACKGROUND

Executive dysfunction (ED) is often observed in subjects diagnosed with obstructive sleep apnea (OSA), but their assessment requires facilities that are not always available. We aim to evaluate the extent to which Frontal Assessment Battery (FAB) discriminates ED in newly diagnosed, untreated, and without-comorbidity OSA patients.

METHODS

Sixty subjects participated in the study. Of these, 40 (31 males and 9 females) were newly diagnosed for OSA through full-night polysomnography (apnea/hypopnea index; M = 39.01, SD = 27.16), untreated, with a mean age of 54.50 years (SD = 8.90), while the remaining 20 (15 males and 5 females) had no symptoms of OSA (M = 51.60 years, SD = 10.70). The instruments used were the following: Questionnaire for Sleep Apnea Risk, Epworth Sleepiness Scale, Mini-Mental State Examination, and FAB.

RESULTS

The group with OSA exhibited significantly lower values in the FAB global score (p = 0.003) and in Conceptualization (p = 0.001) and Mental Flexibility (p = 0.009) subtests. ROC analysis showed adequate discriminative capacity for the FAB global score (AUC = 0.74) and for Conceptualization (AUC = 0.75) and Mental Flexibility (AUC = 0.70) scores.

CONCLUSIONS

The FAB is a short and no-time-consuming tool that can be used to investigate the presence of ED in untreated OSA patients with no comorbidities, providing clinicians with a simple and effective way of detecting the presence of this dysfunction and allowing a more informed decision for the need of a full neuropsychological assessment.

Prevalence of sleep-disordered breathing in Japanese medical students based on type-3 out-of-center sleep test

BACKGROUND

Sleep-disordered breathing (SDB), especially obstructive sleep apnea disorder (OSA), is thought to mainly affect men over the age of 40. Following findings that Asian people are more likely to experience severe OSA, regardless of obesity, we investigated the prevalence of SDB and OSA in a larger sample and in more younger age groups than those described in previous reports.

METHODS

Between 2011 and 2016, 487 medical students (358 males, mean age 24.8 ± 1.9 years; 129 females: mean age 23.8 ± 1.6 years) underwent an out-of-center sleep test using a type-3 portable monitor. The results were analyzed visually.

RESULTS

The mean ± standard deviation of the respiratory event index (REI: events/hour of monitoring) was 5.4 ± 6.7 (6.7 ± 7.5 in male participants, 2.6 ± 2.1 in female participants). There were 170 participants (36.6%) with an REI≥5, including 158 male participants (46.9%) and 12 female participants (9.1%). SDB or undefined OSA with low REI (15 > REI≥5) was observed in 141 participants (30.4%), defined OSA with moderate REI (30 > REI≥15) in 19 participants (4.1%), and defined OSA with high REI (REI≥30) in 10 participants (2.2%). Among the male students, 129 had low REI (38.3%), 19 had moderate REI (5.6%), and 10 had high REI (3.0%). All female participants with OSA events (9.4%) had a low REI.

CONCLUSIONS

The prevalence of OSA in Japanese young adults, especially males under 30 years old, is similar or even higher than that in older age groups described previously. Thus, an aggressive sleep study for SDB might be necessary for the younger generation in the Asian population.

Impact of obstructive sleep apnea on blood pressure and cardiovascular risk factors in Japanese men: A cross-sectional study in work-site group

It has been shown that obstructive sleep apnea (OSA) is related to hypertension and cardiovascular disease; however, the prevalence of OSA in general population and the impact of it on blood pressure especially in Japan has not been well determined. We have conducted a screening test for OSA from 2003 to 2011. In addition, a cross-sectional analysis was performed in 2012 to determine the association of OSA and cardiovascular risk factors in Japanese men (18-69 years of age; mean age, 44.4 ± 0.2). The study group consisted of 2208 male employees, and OSA was evaluated by using the 4% oxygen desaturation index and apnea-hypopnea index (AHI). The prevalence of mild-to-moderate (5≤AHI<30) and severe (AHI≥30) OSA in the studied subjects were 7.1%, and 6.1%, respectively. Among the 135 severe OSA subjects, 105 (77.8%) had been treated with continuous positive airway pressure. Both systolic and diastolic blood pressures (DBP) were significantly increased in the subjects with severe OSA compared with those without OSA. These associations in DBP remained observed after adjustment for age, body mass index (BMI), estimated glomerular filtration rate, HbA_1c, current alcohol intake, current smoking habits, and OSA treatment. DBP in severe OSA subjects were significantly increased in 1807 subjects who were not treated for hypertension or OSA. However, the levels of blood pressures were not decreased by OSA treatment. These results suggest that the prevalence of OSA is relatively high in middle-aged Japanese men and that blood pressures were elevated in the subjects with severe OSA.

Methodological strategies in using home sleep apnea testing in research and practice

PURPOSE

Home sleep apnea testing (HSAT) has increased due to improvements in technology, accessibility, and changes in third party reimbursement requirements. Research studies using HSAT have not consistently reported procedures and methodological challenges. This paper had two objectives: (1) summarize the literature on use of HSAT in research of adults and (2) identify methodological strategies to use in research and practice to standardize HSAT procedures and information.

METHODS

Search strategy included studies of participants undergoing sleep testing for OSA using HSAT. MEDLINE via PubMed, CINAHL, and Embase with the following search terms: "polysomnography," "home," "level III," "obstructive sleep apnea," and "out of center testing."

RESULTS

Research articles that met inclusion criteria (n = 34) inconsistently reported methods and methodological challenges in terms of: (a) participant sampling; (b) instrumentation issues; (c) clinical variables; (d) data processing; and (e) patient acceptability. Ten methodological strategies were identified for adoption when using HSAT in research and practice.

CONCLUSIONS

Future studies need to address the methodological challenges summarized in this paper as well as identify and report consistent HSAT procedures and information.

Normal sleep requires the astrocyte brain-type fatty acid binding protein FABP7

Sleep is found widely in the animal kingdom. Despite this, few conserved molecular pathways that govern sleep across phyla have been described. The mammalian brain-type fatty acid binding protein (Fabp7) is expressed in astrocytes, and its mRNA oscillates in tandem with the sleep-wake cycle. However, the role of FABP7 in regulating sleep remains poorly understood. We found that the missense mutation FABP7.T61M is associated with fragmented sleep in humans. This phenotype was recapitulated in mice and fruitflies bearing similar mutations: Fabp7-deficient mice and transgenic flies that express the FABP7.T61M missense mutation in astrocytes also show fragmented sleep. These results provide novel evidence for a distinct molecular pathway linking lipid-signaling cascades within astrocytes in sleep regulation among phylogenetically disparate species.

Evaluation of Bone Mineral Density by Computed Tomography in Patients with Obstructive Sleep Apnea

STUDY OBJECTIVES

Clinical studies have investigated whether obstructive sleep apnea (OSA) can modulate bone metabolism but data are conflicting. Bone mineral density (BMD) measured by dual-energy x-ray absorptiometry is the standard technique for quantifying bone strength but has limitations in overweight patients (body mass index [BMI] ≥ 25 kg/m(2)). The aim of this study was to examine the association between OSA and BMD by examining CT images that allow true volumetric measurements of the bone regardless of BMI.

METHODS

Lumbar vertebrae BMD was evaluated in 234 persons (180 males and 54 females) by CT scan. The method was calibrated by a phantom containing a known concentration of hydroxyapatite.

RESULTS

BMD was lower in male patients with severe OSA (apnea-hypopnea index [AHI] ≥ 30/h) than non OSA (AHI < 5; p < 0.05), while OSA and BMD had no association in females. Linear and multiple regression analyses revealed that age (p < 0.0001, β = -0.52), hypertension (p = 0.0068, β = -0.17), and the alveolar-arterial oxygen pressure difference (A-aDO2) (p = 0.012, β = -0.15) in males were associated with BMD, while only age (p < 0.0001, β = -0.68) was associated with BMD in females.

CONCLUSION

Males with severe OSA had a significantly lower BMD than non OSA participants. Age, hypertension, and elevation of A-aDO2 were significant factors for BMD by CT imaging. The usefulness of measuring BMD in OSA patients by CT scanning should be studied in future.

Association between physical activity and sleep-disordered breathing in male Japanese workers: a cross-sectional study

BACKGROUND

Whether physical activity reduces the risk of sleep-disordered breathing (SDB) for non-obese people remains unclear. The present cross-sectional study examined the association between physical activity and SDB among non-obese male Japanese workers.

METHODS

All 200 workers in a company in Tokyo, Japan, who drove a motor vehicle as part of their job, were invited to be screened for SDB to prevent traffic accidents. Of these, 195 agreed to participate in this study. The number of apnea and hypopnea episodes occurring during one night was measured using a single-channel airflow monitor to obtain an individual respiratory disturbance index (RDI). SDB was defined as RDI ≥15 apneas/hypopneas/h. Non-obese males (body mass index <30 kg/m²) were included in the analysis. Unconditional logistic regression analysis was used to calculate crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for SDB by physical activity level tertile, as measured by the International Physical Activity Questionnaire.

RESULTS

The prevalence of SDB was 26.9%. The unadjusted analysis showed a significant inverse association between physical activity and SDB: crude ORs for the tertiles of physical activity were 1.00 (low), 1.58 (middle), and 0.27 (high) (95% CI 0.08-0.88; P for trend = 0.007). However, this association was attenuated after adjusting for covariates: Adjusted ORs were 1.00 (low), 1.65 (middle), and 0.41 (high) (95% CI 0.10-1.61; P for trend = 0.11).

CONCLUSIONS

In a cross-sectional study among non-obese male workers in Japan, we found no significant association between physical activity and SDB.

Overcoming sleep disordered breathing and ensuring sufficient good sleep time for a healthy life expectancy

Recent advances in basic and clinical medicine have resulted in major improvements in human health. Currently sleep has been considered an essential factor in maintaining and promoting a healthy life expectancy. Sleep disorders include more than 60 diseases. Sleep disordered breathings (SDB) have 17 disorders, including sleep apnea. SDB usually induces hypoxemia and hypercapnia, which would have significant effects on cells, organs, and the whole body. We have investigated SDB for nearly 35 years. We found that SDB has significant associations with humoral factors, including coagulation systems, the body's protective factors against diseases, and metabolic and organ diseases. Currently we have been giving attention to the associations among SDB, short sleep duration, and obesity. In addition, SDB is important not only in the home but under critical care such as in the perioperative stage. In this review, I would like to describe several aspects of SDB in relation to systemic diseases and overall health based mainly on our published reports.

Relationship between obstructive sleep apnea and endogenous carbon monoxide

Endogenous carbon monoxide (CO) levels are recognized as a surrogate marker for activity of heme oxygenase-1, which is induced by various factors, including hypoxia and oxidative stress. Few reports have evaluated endogenous CO in patients with obstructive sleep apnea (OSA). Whether OSA more greatly affects exhaled or blood CO is not known. Sixty-nine patients with suspected OSA were prospectively included in this study. Exhaled and blood CO were evaluated at night and morning. Blood and exhaled CO levels were well correlated both at night and morning (r = 0.52, P < 0.0001 and r = 0.61, P < 0.0001, respectively). Although exhaled CO levels both at night and morning significantly correlated with total sleep time with arterial oxygen saturation < 90% (ρ = 0.41, P = 0.0005 and ρ = 0.27, P = 0.024, respectively), blood CO levels did not correlate with any sleep parameter. Seventeen patients with an apnea and hypopnea index (AHI) < 15 (control group) were compared with 52 patients with AHI ≥ 15 (OSA group). Exhaled CO levels at night in the OSA group were significantly higher than in the control group (3.64 ± 1.2 vs. 2.99 ± 0.70 ppm, P < 0.05). Exhaled CO levels at night decreased after 3 mo of continuous positive airway pressure (CPAP) therapy in OSA patients (n = 36; P = 0.016) to become nearly the same level as in the control group (P = 0.21). Blood CO levels did not significantly change after CPAP therapy. Exhaled CO was positively related to hypoxia during sleep in OSA patients, but blood CO was not. Exhaled CO might better correlate with oxidative stress associated with OSA than blood CO.

NEW & NOTEWORTHY

Endogenous carbon monoxide (CO) levels are recognized to be a surrogate marker of oxidative stress. No study has evaluated both exhaled and blood CO at the same time in obstructive sleep apnea (OSA) patients. Here we provide evidence that exhaled CO levels positively correlated with hypoxia during sleep in OSA patients, but blood CO levels did not, and that continuous positive airway pressure therapy significantly decreased exhaled CO levels in the OSA group, but did not significantly affect blood CO.

Obstructive sleep apnea syndrome should be considered as a cause of nocturia in younger patients without other voiding symptoms

INTRODUCTION

This study aimed to evaluate urination frequency among patients with obstructive sleep apnea syndrome (OSAS) and the effect of continuous positive airway pressure (CPAP) treatment.

METHODS

We evaluated 138 men with moderate-to-severe OSAS by using polysomnography. Urination status was assessed at baseline and three months using the International Prostate Symptom Score and Overactive Bladder Symptom Score. Nocturia was defined as ≥2 nighttime urinations and patients were classified into Group A (<50 years old with nocturia), Group B (≥50 years old with nocturia), and Group C (patients without nocturia). OSAS severity and other urinary symptoms were also evaluated.

RESULTS

Patients with nocturia exhibited more severe OSAS, compared to patients without nocturia (apnea-hypopnea index [AHI]: 52.0 vs. 44.7; p=0.021). Group A had the worst AHI, but did not have additional voiding symptoms, compared to Group B (p<0.001). The number of urinations was significantly correlated with OSAS severity in <50-year-old patients (p=0.013). CPAP reduced the number of urinations in Group A (75% of patients) and Group B (90% of patients). Patients with and without improved nocturia exhibited significant differences in their baseline OSAS severity (AHI: 53.7 vs. 37.3; p=0.042).

CONCLUSIONS

OSAS severity was associated with the number of urinations in <50-year-old patients. CPAP decreased the nocturia frequency in 85% of patients with nocturia and was most effective in patients with severe AHI. However, additional studies should evaluate voiding volume in order to elucidate the mechanism of nocturia in patients with OSAS.

Cross-Sectional Study of Obstructive Sleep Apnea Syndrome in Japanese Public Transportation Drivers: Its Prevalence and Association With Pathological Objective Daytime Sleepiness

OBJECTIVE

This study investigates obstructive sleep apnea syndrome (OSAS) prevalence among Japanese occupational drivers and factors associated with a pathological level of objective daytime sleepiness.

METHODS

Portable monitoring device (PMD) screening was applied to 2389 Japanese male public transportation traffic drivers. Nocturnal polysomnography (n-PSG) and multiple sleep latency tests (MSLT) were administered to subjects with apnea-hypopnea index (AHI) at least 15 on PMD.

RESULTS

In all, 235 subjects were diagnosed as having OSAS (9.8%). AHI on n-PSG at least 40 and Epworth Sleepiness Scale score at least 11 were extracted as factors associated with mean sleep latency on MSLT less than 5 minutes.

CONCLUSION

Prevalence of OSAS in male Japanese public transportation traffic drivers was 9.8% or greater. Individuals aware of excessive daytime sleepiness and with severe OSAS were inferred as exhibiting a pathological level of objective daytime sleepiness.

Progression of obstructive sleep apnoea syndrome in Japanese patients

PURPOSE

The aggravation of obstructive sleep apnoea syndrome (OSAS) is reportedly associated with weight gain. The present study investigated the factors associated with worsening of respiratory functional parameters in Japanese OSAS patients who showed no body weight change during the follow-up period.

METHODS

A follow-up polysomnography (PSG) was performed in 82 patients with a mean of 7.5 years after the diagnostic PSG, and the apnoea-hypopnoea index (AHI), respiratory event duration, minimum percutaneous oxygen saturation (SpO2), baseline SpO2, and 3 % oxygen desaturation index (ODI) during sleep were compared between the two PSGs. Furthermore, factors associated with worsened AHI, respiratory event duration, and minimum SpO2 were investigated using logistic regression analysis.

RESULTS

No significant differences were observed in AHI, baseline SpO2, and 3 % ODI between the two PSGs. However, there was a significantly increased respiratory event duration and decreased minimum SpO2 observed. In addition, 17 patients had a ≥25 % AHI increase, and the age of 40-60 years and initial OSAS severity (mild and moderate) were the significantly associated factors. Age of ≥60 years and a baseline body mass index (BMI) of ≥25 kg/m(2) were significantly associated with prolonged respiratory event duration. The age of 40-60 years was significantly associated with decreased minimum SpO2.

CONCLUSIONS

Untreated middle-aged patients may be at a high risk for worsened AHI and SpO2 even without weight gain.

Obstructive sleep apnea is a common disorder in the population-a review on the epidemiology of sleep apnea

The prevalence of obstructive sleep apnea (OSA) defined at an apnea-hypopnea index (AHI) ≥5 was a mean of 22% (range, 9-37%) in men and 17% (range, 4-50%) in women in eleven published epidemiological studies published between 1993 and 2013. OSA with excessive daytime sleepiness occurred in 6% (range, 3-18%) of men and in 4% (range, 1-17%) of women. The prevalence increased with time and OSA was reported in 37% of men and in 50% of women in studies from 2008 and 2013 respectively. OSA is more prevalent in men than in women and increases with age and obesity. Smoking and alcohol consumption are also suggested as risk factors, but the results are conflicting. Excessive daytime sleepiness is suggested as the most important symptom of OSA, but only a fraction of subjects with AHI >5 report daytime sleepiness and one study did not find any relationship between daytime sleepiness and sleep apnea in women. Stroke and hypertension and coronary artery disease are associated with sleep apnea. Cross-sectional studies indicate an association between OSA and diabetes mellitus. Patients younger than 70 years run an increased risk of early death if they suffer from OSA. It is concluded that OSA is highly prevalent in the population. It is related to age and obesity. Only a part of subjects with OSA in the population have symptoms of daytime sleepiness. The prevalence of OSA has increased in epidemiological studies over time. Differences and the increase in prevalence of sleep apnea are probably due to different diagnostic equipment, definitions, study design and characteristics of included subjects including effects of the obesity epidemic. Cardiovascular disease, especially stroke is related to OSA, and subjects under the age of 70 run an increased risk of early death if they suffer from OSA.

Association of sleep-disordered breathing with decreased cognitive function among patients with dementia

Sleep is known to be essential for proper cognitive functioning. Sleep disturbance, especially respiratory disturbance during sleep, is a risk factor for the development of dementia. However, it is not known whether hypopnoea during sleep is related to severity of cognitive function in patients already diagnosed with dementia. Considering the high prevalence of sleep problems in aged people, it is important to determine if hypopnoea during sleep contributes to dementia. In addition, it would be desirable to develop a feasible method for objectively evaluating sleep in patients with dementia. For this purpose, a simple sleep recorder that employs single or dual bioparameter recording, which is defined as a type-4 portable monitor, is suitable. In this study, a type-4 sleep recorder was used to evaluate respiratory function during sleep in 111 patients with dementia, and data suggesting a possible relationship with cognitive function levels were examined. Multivariate logistic regression was used to investigate the association of severity of dementia with sleep-disordered breathing, age, diabetes, dyslipidaemia and hypertension. It was found that the respiratory disturbance index was associated with severity of cognitive dysfunction in our subjects. Furthermore, patients younger than 80 years were more susceptible to lower cognitive function associated with sleep-disordered breathing than patients 80 years old or over, because an increase in the respiratory disturbance index was associated with deteriorated cognitive function only in the former age group. These results suggest that proper treatment of sleep apnea is important for the preservation of cognitive function, especially in patients with early-stage dementia.

Diagnostic accuracy of level 3 portable sleep tests versus level 1 polysomnography for sleep-disordered breathing: a systematic review and meta-analysis

BACKGROUND

Greater awareness of sleep-disordered breathing and rising obesity rates have fueled demand for sleep studies. Sleep testing using level 3 portable devices may expedite diagnosis and reduce the costs associated with level 1 in-laboratory polysomnography. We sought to assess the diagnostic accuracy of level 3 testing compared with level 1 testing and to identify the appropriate patient population for each test.

METHODS

We conducted a systematic review and meta-analysis of comparative studies of level 3 versus level 1 sleep tests in adults with suspected sleep-disordered breathing. We searched 3 research databases and grey literature sources for studies that reported on diagnostic accuracy parameters or disease management after diagnosis. Two reviewers screened the search results, selected potentially relevant studies and extracted data. We used a bivariate mixed-effects binary regression model to estimate summary diagnostic accuracy parameters.

RESULTS

We included 59 studies involving a total of 5026 evaluable patients (mostly patients suspected of having obstructive sleep apnea). Of these, 19 studies were included in the meta-analysis. The estimated area under the receiver operating characteristics curve was high, ranging between 0.85 and 0.99 across different levels of disease severity. Summary sensitivity ranged between 0.79 and 0.97, and summary specificity ranged between 0.60 and 0.93 across different apnea-hypopnea cut-offs. We saw no significant difference in the clinical management parameters between patients who underwent either test to receive their diagnosis.

INTERPRETATION

Level 3 portable devices showed good diagnostic performance compared with level 1 sleep tests in adult patients with a high pretest probability of moderate to severe obstructive sleep apnea and no unstable comorbidities. For patients suspected of having other types of sleep-disordered breathing or sleep disorders not related to breathing, level 1 testing remains the reference standard.

Long-term adherence to nasal continuous positive airway pressure therapy by hypertensive patients with preexisting sleep apnea

BACKGROUND AND OBJECTIVE

Although positive screening for and treatment of obstructive sleep apnea (OSA) have been recommended for patients with cardiovascular problems, patient adherence to nasal continuous positive airway pressure (CPAP) therapy primarily for a cardiovascular concern is unknown. Therefore, this study aimed to determine the adherence to CPAP therapy by hypertensive patients with OSA after a screening test performed regardless of OSA-related symptoms.

SUBJECTS AND METHODS

CPAP therapy was administered to 194 of the 1365 hypertensive patients who underwent the screening. The monthly dropout from CPAP therapy and the adequate use level (4h every night, 70% days in a month) were assessed using the Kaplan-Meier analysis over a 3-year follow-up period.

RESULTS

Of the patients, 106 (55%) refused or abandoned the therapy by the end of the follow-up period (adherence, 45%). An adequate use level was maintained by 76 patients (39%). Most of the patients' background characteristics, including age, sex, Epworth sleepiness scale scores, and parameters obtained on polysomnography, were not related to adherence or adequate use level. The good-compliance level on the first visit after CPAP therapy introduction was most strongly related to adherence (95% CI, 0.05-0.32; p<0.001) and adequate use level (95% CI, 0.06-0.33; p<0.05). Fourth quartile of apnea hypopnea index value (greater than 67/h) was also related to adherence (95% CI, 0.21-0.98; p<0.02) and adequate use level (95% CI, 0.19-0.88; p<0.05).

CONCLUSIONS

The adherence and use level in this population may not be satisfactory but are comparable with those in previous sleep center reports treating symptomatic OSA patients. Thus, the present results would encourage hypertensive patients to undergo positive screening for OSA, regardless of OSA-related symptoms. However, an outcomes study with the same cohort is needed.