Body fat distribution and sleep apnea severity in women

Effect of obesity on sleep apnea pathogenesis differs in women versus men: multiple mediation analyses in the retrospective SNOOzzzE cohort

There are multiple mechanisms underlying obstructive sleep apnea (OSA) development. However, how classic OSA risk factors such as body mass index (BMI) and sex portend to OSA development has not been fully described. Thus we sought to evaluate how obesity leads to OSA and assess how these mechanisms differ between men and women. The San Diego Multi-Outcome OSA Endophenotype (SNOOzzzE) cohort includes 3,319 consecutive adults who underwent a clinical in-laboratory polysomnography at the University of California, San Diego, sleep clinic between January 2017 and December 2019. Using routine polysomnography signals, we determined OSA endotypes. We then performed mediation analyses stratified by sex to determine how BMI influenced the apnea-hypopnea index (AHI) using OSA pathophysiological traits as mediators, adjusting for age, race, and ethnicity. We included 2,146 patients of whom 919 (43%) were women and 1,227 (57%) were obese [body mass index (BMI) > 30 kg/m2]. BMI was significantly associated with AHI in both women and men. In men, the adjusted effect of BMI on AHI was partially mediated by a reduction in upper airway stiffness (βstandardized = 0.124), a reduction in circulatory delay (βstandardized = 0.063), and an increase in arousal threshold (βstandardized = 0.029; Pboot-strapped,all < 0.05). In women, the adjusted effect of BMI on AHI was partially mediated by a reduction in upper airway stiffness (βstandardized = 0.05) and circulatory delay (βstandardized = 0.037; Pboot-strapped,all < 0.05). BMI-related OSA pathogenesis differs by sex. An increase in upper airway collapsibility is consistent with prior studies. A reduction in circulatory delay may lead to shorter and thus more events per hour (higher AHI), while the relationship between arousal threshold and OSA is likely complex.NEW & NOTEWORTHY Our data provide important insights into obesity-related obstructive sleep apnea (OSA) pathogenesis, thereby validating, and extending, prior research findings. This is the largest sample size study to examine the relationships between obesity and gender on OSA pathogenesis. The influence of obesity on sleep apnea severity is mediated by different mechanistic traits (endotypes).

Sex differences in sleep, circadian rhythms, and metabolism: Implications for precision medicine

The number of individuals experiencing sleep loss has exponentially risen over the past decades. Extrapolation of laboratory findings to the real world suggests that females are more affected by extended wakefulness and circadian misalignment than males are. Therefore, long-term effects such as sleep and metabolic disorders are likely to be more prevalent in females than in males. Despite emerging evidence for sex differences in key aspects of sleep-wake and circadian regulation, much remains unknown, as females are often underrepresented in sleep and circadian research. This narrative review aims at highlighting 1) how sex differences systematically impinge on the sleep-wake and circadian regulation in humans, 2) how sex differences in sleep and circadian factors modulate metabolic control, and 3) the relevance of these differences for precision medicine. Ultimately, the findings justify factoring in sex differences when optimizing individually targeted sleep and circadian interventions in humans.

Sex-specific differences in presenting symptoms of obstructive sleep apnea

OBJECTIVES

Scant data from India are available on the gender differences in presenting features of Obstructive Sleep Apnea (OSA) in India. This study aims to compare male and female patients with OSA for general characteristics and presenting symptoms.

METHODOLOGY

Retrospective study was done in OSA patients diagnosed in our sleep lab. History, biochemical reports, and polysomnography variables were retrieved from the sleep registry and were compared between males and females.

RESULTS

Out of 514 patients of OSA (367 males; 147 females). Females were older (55.97 ± 9.73 v/s 50.2 + 12.70 years, P<0.001) and more obese (BMI 35.26 ± 7.17 v/s 29.58 ± 5.49 Kg/m2; P<0.001). Waist and hip circumference were significantly higher in the female patients (P = 0.009 and <0.001 respectively). Morning headache, nocturia, fatigability (P < 0.001), and depression (P = 0.005) was more common in females (P = 0.036). Hypersomnia was more commonly seen in males (P < 0.001). Mean diastolic blood pressure was significantly higher in males, although no difference was seen in Systolic BP. Females had higher mean Fasting Blood glucose (FBS) (P = 0.02). Apnea hypopnea index was significantly higher in females {P = 0.01}.

CONCLUSION

Women with OSA are more obese, elderly, and with higher fasting blood glucose than males at the time of diagnosis. Females have a higher prevalence of symptoms like fatigability, depression, nocturia and early morning headache and had more severe AHI than males.

Nasal and maxillary sinus volume change in patients with obstructive sleep apnea after bimaxillary advancement surgery

The airway complex is modified by bimaxillary advancement surgery performed in patients suffering from obstructive sleep apnea (OSA). The aim of the present study is to analyse the volume of nasal and maxillary sinus after bimaxillary advancement surgery in patients suffering from OSA. The maxillary sinus and nasal complex of eighteen patients with OSA was measured through cone-beam computed tomography (CBCT) before and after they were treated with bimaxillary advancement surgery. Digital planning software was used to effectively measure the upper volume changes, as well as, statistical analysis of the results was performed.Methods Eighteen patients were diagnosed with OSA the severity of which was measured by the apnea hypopnea index and were selected and submitted to preoperative and postoperative CBCT scans. Afterwards, datasets were uploaded into therapeutic digital planning software (Dolphin Imaging) to measure the volume of the right and left maxillary sinus and nasal and maxillary sinus complex. Statistically analysis between preoperative and postoperative measures was performed by Student t-test statistical analysis.Results The paired t-test showed statistically significant volumetric reductions in the left maxillary sinus (p = 0.0004), right maxillary sinus (p < 0.0001) and nasal and maxillary sinus complex (p = 0.0009) after bimaxillary advancement surgery performed in patients suffering from OSA.Conclusion The results showed that bimaxillary advancement surgery reduces the maxillary sinus volume as well as, the fossa nasal and sinus complex volume.

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.

Impact of Body Composition on Sleep and Its Relationship with Sleep Disorders: Current Insights

Sleep is involved in many physiological processes and is essential for both physical and mental health. Obesity and sleep deprivation due to sleep disorders are major public health issues. Their incidence is increasing, and they have a wide range of adverse health-related consequences, including life-threatening cardiovascular disease. The impact of sleep on obesity and body composition is well-known, and many studies have shown an association between insufficient or excessive sleep duration and obesity, body fat percentage, and weight gain. However, there is growing evidence of the effects of body composition on sleep and sleep disorders (particularly sleep disordered breathing) through anatomical and physiological mechanisms (nocturnal fluid shift, core body temperature, or diet). Although some research has been conducted on the bidirectional effects of sleep-disordered breathing and body composition, the specific effects of obesity and body composition on sleep and the underlying mechanisms that explain these effects remain unclear. Therefore, this review summarizes the findings on the effects of body composition on sleep and draws conclusions and proposals for future research in this field.

Genome-wide association study of obstructive sleep apnoea in the Million Veteran Program uncovers genetic heterogeneity by sex

BACKGROUND

Genome-wide association studies (GWAS) for obstructive sleep apnoea (OSA) are limited due to the underdiagnosis of OSA, leading to misclassification of OSA, which consequently reduces statistical power. We performed a GWAS of OSA in the Million Veteran Program (MVP) of the U.S. Department of Veterans Affairs (VA) healthcare system, where OSA prevalence is close to its true population prevalence.

METHODS

We performed GWAS of 568,576 MVP participants, stratified by biological sex and by harmonized race/ethnicity and genetic ancestry (HARE) groups of White, Black, Hispanic, and Asian individuals. We considered both BMI adjusted (BMI-adj) and unadjusted (BMI-unadj) models. We replicated associations in independent datasets, and analysed the heterogeneity of OSA genetic associations across HARE and sex groups. We finally performed a larger meta-analysis GWAS of MVP, FinnGen, and the MGB Biobank, totalling 916,696 individuals.

FINDINGS

MVP participants are 91% male. OSA prevalence is 21%. In MVP there were 18 and 6 genome-wide significant loci in BMI-unadj and BMI-adj analyses, respectively, corresponding to 21 association regions. Of these, 17 were not previously reported in association with OSA, and 13 replicated in FinnGen (False Discovery Rate p-value < 0.05). There were widespread significant differences in genetic effects between men and women, but less so across HARE groups. Meta-analysis of MVP, FinnGen, and MGB biobank revealed 17 additional, previously unreported, genome-wide significant regions.

INTERPRETATION

Sex differences in genetic associations with OSA are widespread, likely associated with multiple OSA risk factors. OSA shares genetic underpinnings with several sleep phenotypes, suggesting shared aetiology and causal pathways.

FUNDING

Described in acknowledgements.

A Scoping Review of Sleep Apnea: Where Do We Stand?

Obstructive sleep apnea (OSA), a condition in which there is a recurrent collapse of the upper airway while sleeping, is a widespread disease affecting 5% to 10% people worldwide. Despite several advances in the treatment modalities for OSA, morbidity and mortality remain a concern. Common symptoms include loud snoring, gasping for air during sleep, morning headache, insomnia, hypersomnia, attention deficits, and irritability. Obese individuals, male gender, older age (65+), family history, smoking, and alcohol consumption are well recognized risk factors of OSA. This condition holds the ability to increase inflammatory cytokines, cause metabolic dysfunction, and increase the sympathetic output, all of which exacerbate OSA due to their effect on the cardiovascular system. In this review, we discuss its brief history, risk factors, complications, treatment modalities, and the role of clinicians in curbing its risk.

Association between residential greenness and obstructive sleep apnoea among adults in Southern China

BACKGROUND

No previous study has explored the association of residential greenness with obstructive sleep apnoea (OSA) indexes.

OBJECTIVE

To investigate the association of exposure to residential greenness with OSA indexes in adults in Guangdong Province, Southern China.

METHODS

From January 1, 2005 to December 31, 2015, a total of 3925 participants were recruited from the Sleep Center of Guangdong Provincial People's Hospital. Apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were measured by polysomnography or home sleep test (HST). Participants' daytime sleepiness scores were evaluated using The Epworth Sleeping Scale (ESS). The normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) were used to assess residential greenness levels. Generalized linear regression models were used to assess the associations of residential greenness with OSA indexes after adjusting for multiple covariates.

RESULTS

The mean (standard deviation) age of the participants was 63.3 (14.4) years. In adjusted models, an interquartile range (IQR) increase in 3-year average NDVI was significantly associated with 9.8 % (95 % confidence interval [95 % CI]: 17.5 %, 2.1 %); 14.5 % (95 % CI: 24.5 %, 4.4 %) and 6.9 % (95 % CI: 13.7 %, 0.0 %) decreases in AHI, ODI and ESS scores, respectively. Furthermore, an IQR increase in 3-year average EVI was significantly associated with 7.8 % (95 % CI: 13.7 %, 1.9 %); 10.8 % (95 % CI: 18.3 %, 3.2 %) and 7.2 % (95 % CI: 12.5 %, 2.0 %) declines in AHI, ODI and ESS scores, respectively. Significant associations were only observed among males, adults aged ≥65 years old, and in the warm season.

CONCLUSIONS

Our study indicates that higher residential greenness was significantly associated with lower OSA indexes in adult population in South China, especially in males, in the elderly, and in the warm season.

Are physical inactivity, sitting time and screen time associated with obstructive sleep apnea in adults? A cross-sectional study

BACKGROUND

Sitting time, screen time and low physical activity (PA) levels have been associated with several diseases and all-cause mortality. PA is related to better sleep quality and absence of daytime sleepiness, along with lower risks of obstructive syndrome apnea (OSA). However, studies on the relationship between sitting time, screen time and OSA are scarce in the literature.

OBJECTIVE

To analyze associations between PA levels, sitting time, screen time and OSA among adults with suspected sleep disorder.

DESIGN AND SETTING

Cross-sectional study conducted at Hospital Israelita Albert Einstein.

METHODS

Data were collected from 369 adults with suspected sleep disorders who visited the hospital's neurophysiology clinic between August 2015 and January 2017.

RESULTS

Correlations between hypopnea and PA indicators were demonstrated for total sitting time (0.123; P = 0.019) and total screen time (0.108; P = 0.038). There was also a correlation between latency for rapid-eye-movement sleep (REM_LAT) and total sitting time (0.103; P = 0.047) and a negative correlation between mean oxyhemoglobin saturation (SaO_Avg) and total PA time (-0.103; P = 0.048). There were no associations between PA parameters and apnea-hypopnea index. After adjusting for confounding factors (body mass index, age and gender), sitting time and screen time were not associated with OSA.

CONCLUSION

After adjusting for anthropometric and clinical factors, excessive sitting time or screen time was not associated with OSA in adults suspected of sleep disorders. Age, gender, hypertension, body mass index and waist circumference were associated with OSA.

Obesity, Sex, Snoring and Severity of OSA in a First Nation Community in Saskatchewan, Canada

Sleep disorders have been related to body weight, social conditions, and a number of comorbidities. These include high blood pressure and type 2 diabetes, both of which are prevalent in the First Nations communities. We explored relationships between obstructive sleep apnea (OSA) and risk factors including social, environmental, and individual circumstances. An interviewer-administered survey was conducted with adult participants in 2018−2019 in a First Nations community in Saskatchewan, Canada. The survey collected information on demographic variables, individual and contextual determinants of sleep health, and objective clinical measurements. The presence of OSA was defined as an apnea−hypopnea index (AHI) ≥5. Multiple ordinal logistic regression analysis was conducted to examine relationships between the severity of OSA and potential risk factors. In addition to the survey, 233 men and women participated in a Level 3 one-night home sleep test. Of those, 105 (45.1%) participants were reported to have obstructive sleep apnea (AHI ≥ 5). Mild and moderately severe OSA (AHI ≥ 5 to <30) was present in 39.9% and severe OSA (AHI ≥ 30) was identified in 5.2% of participants. Being male, being obese, and snoring loudly were significantly associated with severity of OSA. The severity of OSA in one First Nation appears relatively common and may be related to mainly individual factors such as loud snoring, obesity, and sex.

Understanding potential associations between anatomic and other factors in OSA severity

PURPOSE

The aim of this prospective study was to investigate associations between nasal/oropharyngeal structures and a range of factors including age, gender, daytime sleepiness, and body mass index (BMI).

METHODS

Patients with OSA were prospectively selected as research participants in rhinomanometric analysis as well as for otolaryngological evaluation. Participants were grouped as follows according to their apnea/hypopnea index (AHI) scores: no OSA (AHI < 5), mild OSA (5 ≤ AHI ≤ 15), moderate OSA (15 ≤ AHI < 30), and severe OSA (AHI ≥ 30). One-way analysis of variance (ANOVA), Kruskal-Wallis H, and Mann-Whitney U tests were performed to assess OSA severity in terms of the relationships between nasal resistance (NR) and anthropometric indices (body mass index (BMI), Friedman tongue position (FTP)), age, and gender.

RESULTS

The study cohort of 177 men and 81 women ranged in age between 21 and 76 years, with BMI ranging from 23 to 45. In total, 37 patients were simple snorers (AHI < 5), and 221 patients were diagnosed with OSA. There was no significant difference among the AHI groups in terms of nasal volume (Vol05) (p = 0.952), mean flow (p = 0.778), and mean NR total (p = 0.723). A statistically significant difference was found between the AHI groups in terms of mean BMI and median FTP scores (p < 0.001).

CONCLUSION

This study provides evidence that that the oropharyngeal region (oropharynx, tongue, and vallecula) is a more important determinant of OSA severity than the nasal region.

Genome-wide association study of neck circumference identifies sex-specific loci independent of generalized adiposity

BACKGROUND/OBJECTIVES

Neck circumference, an index of upper airway fat, has been suggested to be an important measure of body-fat distribution with unique associations with health outcomes such as obstructive sleep apnea and metabolic disease. This study aims to study the genetic bases of neck circumference.

METHODS

We conducted a multi-ethnic genome-wide association study of neck circumference, adjusted and unadjusted for BMI, in up to 15,090 European Ancestry (EA) and African American (AA) individuals. Because sexually dimorphic associations have been observed for anthropometric traits, we conducted both sex-combined and sex-specific analysis.

RESULTS

We identified rs227724 near the Noggin (NOG) gene as a possible quantitative locus for neck circumference in men (N = 8831, P = 1.74 × 10-9) but not in women (P = 0.08). The association was replicated in men (N = 1554, P = 0.045) in an independent dataset. This locus was previously reported to be associated with human height and with self-reported snoring. We also identified rs13087058 on chromosome 3 as a suggestive locus in sex-combined analysis (N = 15090, P = 2.94 × 10-7; replication P =0.049). This locus was also associated with electrocardiogram-assessed PR interval and is a cis-expression quantitative locus for the PDZ Domain-containing ring finger 2 (PDZRN3) gene. Both NOG and PDZRN3 interact with members of transforming growth factor-beta superfamily signaling proteins.

CONCLUSIONS

Our study suggests that neck circumference may have unique genetic basis independent of BMI.

Importance of Anthropometric Measurements to Determine Cardiometabolic Diseases in Obstructive Sleep Apnea Syndrome

OBJECTIVE

Obesity is considered a major risk factor for obstructive sleep apnea syndrome (OSAS). This study aimed to examine the correlation between anthropometric measurements, which have been recently defined and are indicative of abdominal obesity and cardiometabolic diseases, OSAS severity, and polysomnography (PSG) parameters in patients with OSAS.

MATERIAL AND METHODS

This retrospective cohort study included patients who underwent all-night polysomnography with a prediagnosis of OSAS. These patients were categorized as having mild (5-15), moderate (15-30), and severe (>30) OSAS according to the apnea-hypopnea index (AHI). The anthropometric measurements used in the study consisted of waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), (waist/hip)-to-height ratio (WHHR), a body shape index (ABSI), body adiposity index (BAI), abdominal volume index (AVI), and conicity index (CI).

RESULTS

A total of 410 individuals were enrolled in the study (31 control subjects and 129 with mild, 101 with moderate, and 149 with severe OSAS). A significant difference was observed between groups in terms of all anthropometric measurements (p<0.05). The difference between the groups was significant in terms of diabetes mellitus, hypertension, and cardiovascular disease (p<0.05). There was a significant correlation between each of the anthropometric measurements and the PSG parameters. In the receiver operating characteristic analysis, cutoff values that predicted severe OSAS were ABSI>0.08, BAI>28.29, AVI>25.54, and CI>1.37. Multiple regression analyses demonstrated that age, sex, and AVI were independent predictors that determine OSAS presence.

CONCLUSION

Anthropometric parameters that are indicators of abdominal obesity were found to be robustly correlated with cardiometabolic diseases and the severity of OSAS.

Positional Sleep Apnea Among Regional and Remote Australian Population and Simulated Positional Treatment Effects

PURPOSE

To assess the prevalence of positional sleep apnea (POSA) and its predictors in patients diagnosed to have obstructive sleep apnea (OSA) in the regional and remote population of the Northern Territory of Australia over a two-year study period (2018 and 2019).

PATIENTS AND METHODS

Of the total 1463 adult patients who underwent a diagnostic polysomnography (PSG), 946 patients were eligible to be included in the study, of them, 810 consecutive patients with OSA (Apnea-Hypopnea Index (AHI) ≥ 5) who slept >4 h and had ≥30 min sleep in both supine and lateral positions were assessed. Patients were considered to have POSA if supine AHI to lateral AHI ratio ≥2. The likely comparative impact of use of continuous positive airway therapy (CPAP) or positional therapy (PT) on disease severity was evaluated using model simulation.

RESULTS

A total of 495/810 (61%) patients had POSA, the majority were males (68% vs 60%, p=0.013) and non-Indigenous Australians (93% vs 87%, p=0.004). POSA patients were younger (mean difference 2.23 years (95% CI 0.27, 4.19)), less obese (BMI mean difference 3.06 (95% CI 2.11, 4.01)), demonstrated less severe OSA (p < 0.001) and a greater proportion reported alcohol consumption (72% vs 62%, p=0.001) as compared to those with non-POSA. Using the simulation model, if patients with POSA use PT two-thirds (323/495, 65%) would obtain significant improvement of their OSA severity, with one in five (92/495, 19%) displaying complete resolution. Comparing this to simulated CPAP therapy, where the majority (444/495, 90%) will show significant improvement, and one-third (162/495, 33%) will display complete resolution.

CONCLUSION

POSA needs to be routinely recognised and positional therapy integrated in practice especially in the remote regions and in the developing world when effective methods are in place to monitor positional therapy.

Gender Differences in the Clinical and Polysomnographic Characteristics Among Australian Aboriginal Patients with Obstructive Sleep Apnea

BACKGROUND

In this study, we assessed the clinical and polysomnographic (PSG) characteristics according to gender among Australian Aboriginal men and woman diagnosed to have obstructive sleep apnea (OSA).

METHODS

In this retrospective study, all adult Aboriginal patients over 18 years of age diagnosed to have OSA with an apnea hypopnea index (AHI) > 5/hour over a 5 year period were included.

RESULTS

Of the 337 patients (168 females and 169 males), who underwent a diagnostic PSG, 297 (88%) were diagnosed to have OSA (AHI) >5/hour), 154/297 males (52%) and 143/297 females (48%). Amongst male and female patients with OSA, 63% and 37% were in the severe spectrum (AHI>30/hour). The male cohort had higher stage N1 NREM sleep (P<0.001), reduced N3 NREM sleep (P<0.001), higher AHI severity (P<0.001), higher NREM AHI (P<0.001), and high arousal index (P<0.005). REM sleep-related AHI was higher among female patients with all severity of OSA, along with severe oxygen desaturation during REM sleep. Among patients with severe OSA, the female cohort were younger (age 46 years vs 49 years, P=0.030) and had higher BMI with all severity of OSA, while males had larger neck circumference compared to females. Hypertension increased the odds of severe OSA versus the combined odds of mild and moderate OSA for both genders.

CONCLUSION

This study highlights some important differences in the way sleep apnea manifests in Australian Aboriginal males and females and further studies are warranted to explore avenues to look for a physiological basis for these observations and targeted interventions.

Role of menopause and hormone replacement therapy in sleep-disordered breathing

There are suggestions that the loss of female sex hormones following menopause is critical for the development or progression of sleep-disordered breathing (SDB). We conducted a review of the literature on the role of menopause and hormone replacement therapy (HRT) in SDB risk. There is an increase in SDB during the menopausal transition period, but data on an effect beyond that of increasing age and changes in body habitus are weak or absent. Early community-based, observational studies reported a protective effect by HRT on SDB prevalence, but this could possibly be explained as a healthy user effect. Interventional studies of the effect of HRT on SDB are sparse, with only a few randomized placebo-controlled studies, often performed on small samples of women without clinically significant SDB. HRT regimens have varied and all the studies are fairly old. They do not definitely assure the alleviation of SDB and HRT cannot thus be recommended as treatment for SDB. It is concluded that there is no evidence that female sex hormone changes during menopause per se are able to explain the increase in SDB in midlife women and conclusions on the effect of HRT on SDB cannot be drawn from the current literature.

The prediction of obstructive sleep apnea severity based on anthropometric and Mallampati indices

Background

Obstructive sleep apnea (OSA) is a common health issue with serious complications. Regarding the high cost of the polysomnography (PSG), sensitive and inexpensive screening tools are necessary. The objective of this study was to evaluate the predictive value of anthropometric and Mallampati indices for OSA severity in both genders.

Materials and Methods

In a cross-sectional study, we evaluated anthropometric data and the Mallampati classification for the patients (n = 205) with age >18 and confirmed OSA in PSG (Apnea-Hypopnea Index [AHI] >5). For predicting the severity of OSA, we applied a decision tree (C5.0) algorithm, with input and target variables considering two models (Model 1: AHI ≥15 with Mallampati >2, age >51 years, and neck circumference [NC] >36 cm and Model 2: AHI ≥30 with condition: gender = female, body mass index (BMI) >35.8, and age >44 years or gender = male, Mallampati ≥2, and abdominal circumference (AC) >112 then AHI ≥30).

Results

About 54.1% of the patients were male. Mallampati, age, and NCs are important factors in predicting moderate OSA. The likelihood of moderate OSA severity based on Model 1 was 94.16%. In severe OSA, Mallampati, BMI, age, AC, and gender are more predictive. In Model 2, gender had a significant role. The likelihood of severe OSA based on Model 2 in female patients was 89.98% and in male patients was 90.32%. Comparison of the sensitivity and specificity of both models showed a higher sensitivity of Model 1 (93.5%) and a higher specificity of Model 2 (89.66%).

Conclusion

For the prediction of moderate and severe OSA, anthropometric and Mallampati indices are important factors.

Correlations between Waist and Neck Circumferences and Obstructive Sleep Apnea Characteristics

PURPOSE

The body mass index (BMI), an estimate of body fat, provides a rather imprecise indication of risk for obstructive sleep apnea (OSA). We examined whether other measures, including waist and neck circumference, provide improved indicators of risk in treatment-naïve OSA subjects.

METHODS

We studied 59 OSA subjects [age, 48.8±10.0 years; BMI, 31.9±6.6 kg/m²; apnea-hypopnea-index (AHI), 38.5±23.0 events/hour; sleep efficiency index (SEI, n=52), 78.6±14.4%; lowest oxygen saturation (SaO₂ nadir), 79.5±8.0%; systolic blood pressure (BP), 127.4±15.7 mmHg; diastolic BP, 80.1±9.1 mmHg; 43 male), and determined waist and neck circumferences (waist, 107.4±15.3 cm; neck, 41.8±4.7 cm), daytime sleepiness [Epworth sleepiness scale (ESS), 8.7±4.6], sleep quality [Pittsburgh sleep quality index (PSQI), 8.5±4.1], depression levels [Beck depression inventory II (BDI-II), 6.6±5.7), and anxiety levels [Beck anxiety inventory (BAI), 6.2±7.2]. We used partial correlation procedures (covariates, age and gender) to examine associations between BMI, waist, and neck circumferences vs. AHI, sleep, and neuropsychological variables.

RESULTS

BMI, waist, and neck circumferences were significantly correlated with SaO₂ nadir (BMI; r=-0.423, p=0.001; waist; r=-0.457, p<0.001; neck; r=-0.263, p=0.048), AHI (BMI; r=0.349, p=0.008; waist; r=0.459, p<0.001; neck; r=0.276, p=0.038), and systolic BP (BMI; r=0.354, p=0.007; waist; r=0.321, p=0.015; neck; r=0.388, p=0.003). SEI was significantly correlated with waist circumference (r=0.28, p=0.049), but higher with BMI (r=0.291, p=0.04).

CONCLUSIONS

No other significant waist or neck correlations emerged. This study suggests that waist and neck measures correlate better than BMI with select disease severity (SaO₂ nadir and AHI) in OSA subjects. The findings offer an easily-measured, ancillary means to assess OSA risk.

Review of and Updates on Hypertension in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a prevalent sleep disorder as is hypertension (HTN) in the 21st century with the rising incidence of obesity. Numerous studies have shown a strong association of OSA with cardiovascular morbidity and mortality. There is overwhelming evidence supporting the relationship between OSA and hypertension (HTN). The pathophysiology of HTN in OSA is complex and dependent on various factors such as sympathetic tone, renin-angiotensin-aldosterone system, endothelial dysfunction, and altered baroreceptor reflexes. The treatment of OSA is multifactorial ranging from CPAP to oral appliances to lifestyle modifications to antihypertensive drugs. OSA and HTN both need prompt diagnosis and treatment to help address the growing cardiovascular morbidity and mortality due to these two entities.

Identification of significant obstructive sleep apnoea in the obese patient: development of the novel DX-OSA score

BACKGROUND AND OBJECTIVES

There is a high prevalence of undiagnosed obstructive sleep apnoea (OSA) in obese surgical patients. We investigated the extent to which anthropometric measurements can be used to identify the presence of significant OSA (Apnoea/Hypopnoea Index (AHI) ≥ 20) in adult patients.

MATERIALS AND METHODS

We prospectively studied 1357 adult patients scheduled for elective laparoscopic bariatric surgery. Prior to surgery, body mass index (BMI), gender, neck circumference, STOP-Bang score, SpO₂, neck and trunk fat (by dual X-ray absorptiometry) were recorded. All patients with a STOP-Bang score ≥ 5 underwent polysomnography. Auto-titrated Positive Airway Pressure (APAP) therapy was instituted when AHI ≥ 20/h. Predictors of OSA were identified and their cut-off values determined.

RESULTS

In total, 1357 patients were screened; 345 patients underwent preoperative polysomnography; 190 had AHI ≥ 20/h and received APAP treatment. The novel Dual X-Ray-Obstructive Sleep Apnoea (DX-OSA) score was derived from the data. The score included 6 items: the STOP-Bang score, BMI, neck fat, trunk fat, baseline SpO₂, and Expiratory Reserve Volume (ERV), and its sensitivity, specificity, positive-predictive values, negative-predictive values, likelihood ratios, and post-test probabilities determined. At a cut-off of 3, the DX-OSA score had the same sensitivity as the STOP-bang score, but better specificity. The lowest likelihood ratio was found for STOP-Bang and the highest for the DX-OSA score (OSA probability > 83%).

CONCLUSION

The DX-OSA score may be useful for identifying obese patients with significant OSA who require CPAP (continuous positive airway pressure) treatment, and CPAP could be commenced without the need for polysomnography, therefore, without delaying surgery.

Prediction of the severity of obstructive sleep apnea by anthropometric features via support vector machine

To develop an applicable prediction for obstructive sleep apnea (OSA) is still a challenge in clinical practice. We apply a modern machine learning method, the support vector machine to establish a predicting model for the severity of OSA. The support vector machine was applied to build up a prediction model based on three anthropometric features (neck circumference, waist circumference, and body mass index) and age on the first database. The established model was then valided independently on the second database. The anthropometric features and age were combined to generate powerful predictors for OSA. Following the common practice, we predict if a subject has the apnea-hypopnea index greater then 15 or not as well as 30 or not. Dividing by genders and age, for the AHI threhosld 15 (respectively 30), the cross validation and testing accuracy for the prediction were 85.3% and 76.7% (respectively 83.7% and 75.5%) in young female, while the negative likelihood ratio for the AHI threhosld 15 (respectively 30) for the cross validation and testing were 0.2 and 0.32 (respectively 0.06 and 0.1) in young female. The more accurate results with lower negative likelihood ratio in the younger patients, especially the female subgroup, reflect the potential of the proposed model for the screening purpose and the importance of approaching by different genders and the effects of aging.

Body Fat Distribution Ratios and Obstructive Sleep Apnea Severity in Youth With Obesity

STUDY OBJECTIVES

Obesity and regional fat distribution, measured by neck fat mass percentage using dual-energy X-ray absorptiometry (DXA), correlate with obstructive sleep apnea (OSA) severity in adults. In obese children, neck-to-waist-circumference ratio predicts OSA. This study examined associations between body fat percentage and distribution and sleep-disordered breathing (SDB) severity in obese youth, measured with DXA.

METHODS

Cross-sectional retrospective study conducted at a tertiary children's hospital. Participants were aged 6 to 18 years with obesity (body mass index [BMI] > 99th percentile [BMI z-score 2.35] or > 95th percentile with comorbidity). They underwent polysomnography and DXA to quantify body fat percentage and distribution ratios (neck-to-abdominal fat percentage [NAF % ratio]). SDB was defined as apnea-hypopnea index (AHI) > 5 and OSA as obstructive AHI (OAHI) > 1 event/h. Relationships of BMI z-score and NAF % ratio to log AHI and log OAHI were evaluated.

RESULTS

Thirty individuals participated; 18 male; median age 14.1 years. Twenty-four individuals had BMI z-scores > 2.35. Ten had AHI > 5 events/h. NAF % ratio was significantly associated with log AHI in males and with log OAHI in all, whereas total fat mass percent was not. The association between log OAHI and NAF % ratio was significant in males, but not females. NAF % ratio was significantly associated with log OAHI in those with BMI z-score above 2.35.

CONCLUSIONS

NAF % ratio was associated with OSA severity in males and youth with BMI > 99th percentile; however, total fat mass percentage was not, suggesting that body fat distribution is associated with OSA risk in youth.

Obstructive Sleep Apnea

Obstructive sleep apnea syndrome (OSAS) is a potentially serious disorder attacking millions of people around the world. Many of these individuals are undiagnosed, and even though diagnosed often exhibit a poor compliance with the use of continuous positive airway pressure at nights, a very effective nonsurgical treatment. A variety of surgical procedures have been proposed to manage and treat OSA. This article throws insights into assessing the sites of obstruction and a number of surgical procedures designed to address OSA. The scope of this article is to provide information to dentists which enables them to identify the patients who have OSAS and to guide these patients in making informed decisions regarding treatment options.

Impact of gender and sleep position on relationships between anthropometric parameters and obstructive sleep apnea syndrome

OBJECTIVE

Considering the mechanisms by which obesity affects obstructive sleep apnea syndrome (OSAS) and the differences of fat distribution depending on gender, associations between anthropometric parameters, and OSAS may differ depending on gender or sleep position. We analyzed the impact of gender and sleep position on the relationship between fat distribution and development of OSAS.

METHODS

One thousand thirty-two consecutive subjects were analyzed. Recorded anthropometric measurements and overnight polysomnographic data of the subjects were reviewed retrospectively. The presence of OSAS was defined by the respiratory disturbance index (RDI) ≥5 with documented symptoms of excessive daytime sleepiness.

RESULTS

Eight hundred fifty-eight males and 174 females were included. Male subjects had significantly higher body mass index (BMI), larger waist circumference (WC), and lower percent of overall body fat (P < 0.0001, P < 0.0001, and P < 0.0001, respectively). The severity of OSAS was significantly higher in male subjects (RDI 26.9 ± 22.4 in males vs. 10.2 ± 13.8 in females, P < 0.0001). In male subjects, BMI, WC, and overall body fat were significantly associated with severity of OSAS and had larger impacts on supine RDI than lateral RDI. Overall body fat was not associated with severity of OSAS in female subjects, and there were no significant differences of the associations between all anthropometric parameters and RDIs depending on sleep position.

CONCLUSIONS

Evaluation of the correlation of anthropometric data with severity of OSAS should consider sleep position as well as gender.

The Interaction of Obesity and Metabolic Syndrome in Determining Risk of Complication Following Total Joint Arthroplasty

BACKGROUND

The arthroplasty population is increasingly comorbid, and current quality improvement initiatives demand accurate risk stratification. Metabolic syndrome (MetS) has been identified as a risk factor for adverse events after arthroplasty; however, its interaction with obesity in contributing to risk is unclear.

METHODS

A retrospective analysis of all Medicare patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA) at a single institution from 2009 to 2013 investigated the interaction between MetS, body mass index (BMI), and risk for Centers for Medicare and Medicaid Services (CMS)-reportable complications, readmission, and discharge disposition.

RESULTS

A total of 1462 patients (942 TKA, 538 THA) were included, of which 16.2% had MetS. Regression analysis found that MetS was significantly related to risk of CMS complications (odds ratio [OR] = 1.96, 95% confidence interval [CI] 1.16-3.31, P = .012) and nonhome discharge (OR = 1.78, 95% CI 1.39-2.27, P < .001), but not readmission (OR = 1.23, 95% CI 0.7-2.18, P = .485). Within the MetS cohort, increasing BMI was not associated with increasing complications (P = .726) or readmissions (P = .206) but was associated with nonhome discharge (OR = 1.191 per unit increase in BMI, 95% CI 1.038-1.246, P = .001).

CONCLUSION

MetS increases risk for CMS-reportable complications and nonhome discharge disposition after THA and TKA regardless of BMI. Obesity is of less value than MetS in assessing overall risk for complication after THA and TKA.

Pharyngeal collapsibility during sleep is elevated in insulin-resistant females with morbid obesity

Insulin resistance is associated with sleep apnoea, leading us to hypothesise that it is also associated with elevations in pharyngeal collapsibility, even in the absence of sleep apnoea.90 bariatric patients were characterised for sleep apnoea, pharyngeal collapsibility and insulin resistance. Patients with a respiratory disturbance index (RDI) >10 events·h(-1), diabetes mellitus, tonsillar hypertrophy and pulmonary disease were excluded. The remaining 14 females underwent collapsibility measurements (passive critical pressure, Pcritp ) during non-rapid eye movement sleep. The homeostasis model assessment (HOMA) index, a measure of insulin resistance, was derived from measurements of fasting glucose and insulin levels, and compared to Pcritp Groups with high Pcritp compared to low Pcritp did not differ in age, body mass index or RDI. HOMA and insulin were elevated in the high Pcritp group compared to the low Pcritp group (p<0.02). Pcritp correlated with HOMA (Spearman's ρ=0.565, 95% CI 0.104-0.862; p=0.035) and insulin (Spearman's ρ=0.609 95% CI 0.196-0.835; p=0.021).Obese insulin-resistant subjects without frank diabetes or sleep apnoea demonstrate preclinical elevations in pharyngeal collapsibility, which may increase their susceptibility to sleep apnoea. Our findings suggest that insulin resistance could play a significant role in sleep apnoea pathogenesis by generating requisite elevations in pharyngeal collapsibility.

A Pilot Study of the Inability to Fit Hands Around Neck as a Predictor of Obstructive Sleep Apnea

Background:

Considering the high estimates of undiagnosed and untreated obstructive sleep apnea (OSA), there is a need for simple and accurate diagnostic tests. Neck circumference has long been correlated with OSA, but its usefulness as a diagnostic tool has been limited.

Aims:

We proposed to evaluate the value of a simple neck grasp test to help identify OSA. We hypothesized that the inability of a patient in a sleep clinic to fit their hands around their neck is predictive of OSA.

Materials and Methods:

A retrospective review of medical records of patients evaluated in a general sleep clinic was performed. Easy sleep apnea predictor (ESAP) positive was defined as the inability to place the hands around the neck with digits touching in the anterior and posterior. ESAP negative was the ability to place hands around the neck. Positive for OSA in this symptomatic sleep clinic population was defined as an apnea–hypopnea index (AHI) of ≥5.

Results:

A total of 47 subjects (36% female) had ESAP data available, which were reviewed. The mean age was 51.6 years (SD 14.4, range 29-81 years). The mean body mass index (BMI) was 38.8 (SD 9.9, range 20.4-69.5). Review showed 87.2% (N = 41) tested positive for OSA by AHI of ≥5. The sensitivity and specificity of ESAP were 68.3% and 100%, respectively. The positive predictive power was 100% and the negative predictive power was 31.6%.

Conclusion:

As we hypothesized, ESAP positive (inability to span neck) was predictive of OSA in a population of sleep clinic patients. An ESAP positive test was 100% predictive of the presence of OSA (AHI of ≥5). ESAP shows promise for ease of clinical use to predict the presence of OSA in a general sleep clinic population.

Sleep-Disordered Breathing in Adolescents and Younger Adults: A Representative Population-Based Survey in Chile

BACKGROUND

Prevalence and potential risk contributors of sleep-disordered breathing (SDB) in adolescents and younger adults remain unclear. We hypothesized that SDB prevalence in younger Hispanic adults is higher than the limited evidence indicates.

METHODS

This is a population-based study of Hispanic subjects surveyed as part of the Chilean National Health Survey database. For this study, only subjects aged 15 to 40 years were included. Sleep and demographic questionnaires were used to assess SDB prevalence and its risk factors. Anthropometric measurements were performed in each subject. Prevalence was calculated for each SDB-related symptom. A regression model was constructed to investigate demographic risk factors of SDB.

RESULTS

A total of 2,147 subjects were included. Mean age (± SD) was 27.2 ± 7.2 years, n = 899 (42%) were men. Habitual snoring was highly prevalent, with an average of 53.8% in men and 38.3% in women. Snoring, witnessed apneas, and daytime somnolence increased continuously with age, with an abnormal SDB questionnaire score detected in 2.5%. Reported sleep duration was 7.61 ± 1.67 hours during weekdays and 8.27 ± 2.11 hours during weekends. Snoring frequency was significantly higher in men than women at nearly all age groups, and an adjusted regression model (OR [95% CI]) identified male sex (2 [1.6-2.5]; P < .001) and BMI (1.08 [1.03-1.12]; P < .001) as independent risk factors for snoring.

CONCLUSION

The risk of SDB is highly prevalent in younger adults, even in females, and increases with age and BMI. The high prevalence and low awareness justify active screening and treatment of SDB in this population.

Analysis of respiratory events in obstructive sleep apnea syndrome: Inter-relations and association to simple nocturnal features

OBJECTIVE

This study carefully evaluates the association of different respiration-related events to each other and to simple nocturnal features in obstructive sleep apnea-hypopnea syndrome (OSAS). The events include apneas, hypopneas, respiratory event-related arousals and snores.

METHODS

We conducted a statistical study on 158 adults who underwent polysomnography between July 2012 and May 2014. To monitor relevance, along with linear statistical strategies like analysis of variance and bootstrapping a correlation coefficient standard error, the non-linear method of mutual information is also applied to illuminate vague results of linear techniques.

RESULTS

Based on normalized mutual information weights (NMIW), indices of apnea are 1.3 times more relevant to AHI values than those of hypopnea. NMIW for the number of blood oxygen desaturation below 95% is considerable (0.531). The next relevant feature is "respiratory arousals index" with NMIW of 0.501. Snore indices (0.314), and BMI (0.203) take the next place. Based on NMIW values, snoring events are nearly one-third (29.9%) more dependent to hypopneas than RERAs.

CONCLUSION

1. The more sever the OSAS is, the more frequently the apneic events happen. 2. The association of snore with hypopnea/RERA revealed which is routinely ignored in regression-based OSAS modeling. 3. The statistical dependencies of oximetry features potentially can lead to home-based screening of OSAS. 4. Poor ESS-AHI relevance in the database under study indicates its disability for the OSA diagnosis compared to oximetry. 5. Based on poor RERA-snore/ESS relevance, detailed history of the symptoms plus polysomnography is suggested for accurate diagnosis of RERAs.

Association between pterygoid hamulus length and apnea hypopnea index in patients with obstructive sleep apnea: a combined three-dimensional cone beam computed tomography and polysomnographic study

OBJECTIVE

The purpose of this study was to investigate the relationships among the pterygoid hamulus (PH), the maxillo-mandibular complex to the pharynx, the upper airway, and the soft palate and a possible connection to sleep apnea severity as assessed by polysomnography.

STUDY DESIGN

A total of 100 left and right sides of the PH were retrospectively measured by two observers from 50 cone beam computed tomography images by using three-dimensional rendering program in patients with obstructive sleep apnea (33 males and 17 females, with a mean age of 56.8 years; range 32-82 years).

RESULTS

The mean apnea hypopnea index was 30.2 (range 0-95). A linear regression analysis on the apnea hypopnea index with the total length of the PH adjusted for gender, body mass index, neck circumference, and age showed a statistically significant association: (-0.234(∗); P = .005). None of the other variables reached formal significance.

CONCLUSION

The pterygoid hamulus length is inversely associated with sleep apnea severity. Our study provides further insight into the pathophysiology of sleep apnea, with the result that PH length could be a future supplementary measurement to help clinicians to stratify and determine the best treatment options for patients with obstructive sleep apnea.

Elevated body mass index and maintenance of cognitive function in late life: exploring underlying neural mechanisms

BACKGROUND

Obesity is associated with vascular risk factors that in turn, may increase dementia risk. However, higher body mass index (BMI) in late life may be neuroprotective. The possible neural mechanisms underlying the benefit of higher BMI on cognition in older adults are largely unknown. Thus, we used functional connectivity magnetic resonance imaging (fcMRI) to examine: (1) the relationship between BMI and functional brain connectivity; and (2) the mediating role of functional brain connectivity in the association between baseline BMI and change in cognitive function over a 12-month period.

METHODS

We conducted a 12-month, prospective study among 66 community-dwelling older adults, aged 70 to 80 years, who were categorized as: normal weight (BMI from 18.50 to 24.99); overweight (BMI from 25.00 to 29.99); and obese (BMI ≥ 30.00). At baseline, participants performed a finger-tapping task during fMRI scanning. Relevant neural networks were initially identified through independent component analysis (ICA) and subsequently examined through seed-based functional connectivity analysis. At baseline and 12-months, we measured three executive cognitive processes: (1) response inhibition; (2) set shifting; and (3) working memory.

RESULTS

Obese individuals showed lower task-related functional connectivity during finger tapping in the default mode network (DMN) compared with their healthy weight counterparts (p < 0.01). Lower task-related functional connectivity in the DMN at baseline was independently associated with better working memory performance at 12-months (p = 0.02). Finally, DMN functional connectivity during finger tapping significantly mediated the relationship between baseline BMI and working memory at 12-months (indirect effect: -0.155, 95% confidence interval [-0.313, -0.053]).

CONCLUSIONS

These findings suggest that functional connectivity of the DMN may be an underlying mechanism by which higher BMI confers protective effects to cognition in late life.

Obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. The syndrome is particularly prevalent in middle-aged and older adults. The mechanism by which the upper airway collapses is not fully understood but is multifactorial and includes obesity, craniofacial changes, alteration in upper airway muscle function, pharyngeal neuropathy and fluid shift towards the neck. The direct consequences of the collapse are intermittent hypoxia and hypercapnia, recurrent arousals and increase in respiratory efforts, leading to secondary sympathetic activation, oxidative stress and systemic inflammation. Excessive daytime sleepiness is a burden for the majority of patients. OSAS is also associated with cardiovascular co-morbidities, including hypertension, arrhythmias, stroke, coronary heart disease, atherosclerosis and overall increased cardiovascular mortality, as well as metabolic dysfunction. Whether treating sleep apnoea can fully reverse its chronic consequences remains to be established in adequately designed studies. Continuous positive airway pressure (CPAP) is the primary treatment modality in patients with severe OSAS, whereas oral appliances are also widely used in mild to moderate forms. Finally, combining different treatment modalities such as CPAP and weight control is beneficial, but need to be evaluated in randomized controlled trials. For an illustrated summary of this Primer, visit: http://go.nature.com/Lwc6te.

Correlation of cephalometric and anthropometric measures with obstructive sleep apnea severity

Introduction: Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) often have associated changes in craniofacial morphology and distribution of body fat, either alone or in combination.

Aim: To correlate cephalometric and anthropometric measures with OSAHS severity by using the apnea-hypopnea index (AHI).

Method: A retrospective cephalometry study of 93 patients with OSAHS was conducted from July 2010 to July 2012. The following measurements were evaluated: body mass index (BMI), neck circumference (NC), waist circumference (WC), hip circumference (HC), the angles formed by the cranial base and the maxilla (SNA) and the mandible (SNB), the difference between SNA and SNB (ANB), the distance from the mandibular plane to the hyoid bone (MP-H), the space between the base of the tongue and the posterior pharyngeal wall (PAS), and the distance between the posterior nasal spine and the tip of the uvula (PNS-P). Means, standard deviations, and Pearson's correlation coefficients were calculated and analyzed.

Results: AHI correlated significantly with BMI (r = 0.207, p = 0.047), NC (r = 0.365, p = 0.000), WC (r = 0.337, p = 0.001), PNS-P (r = 0.282, p = 0.006), and MP-H (r = 0.235, p = 0.023).

Conclusion: Anthropometric measurements (BMI, NC, and WC) and cephalometric measurements (MP-H and PNS-P) can be used as predictors of OSAHS severity.

Neck circumference percentile: A screening tool for pediatric obstructive sleep apnea

RATIONALE

Large neck circumference (NC) is associated with obstructive sleep apnea (OSA) in adults, especially males. Since NC changes with age and sex, a lack of reference ranges makes neck size difficult to assess as a screening tool in children.

METHODS

Using a population-based dataset of 1,913 children, we developed reference ranges for NC by age and sex for children aged 6-17 years. In this study, we collected NC data on 245 children aged 6-17 years presenting to the Children's Hospital of Eastern Ontario for polysomnography. The association between NC>the 95th percentile and OSA (total apnea-hypopnea-index>5 events/hr and/or obstructive-apnea-index ≥ 1 event/hr) was explored. Thresholds of BMI percentile and waist circumference were also examined.

RESULTS

Individuals with NC>95th percentile for age and sex had increased risk of OSA (relative risk 1.7 [95% CI 1.0-3.0], P=0.04), compared to those with NC ≤ 95th percentile. BMI ≥ 95th percentile gave similar results (relative risk 1.8 [95% CI 1.1-2.9], P=0.02). When examined by sex, the association was significant in males ≥ 12 years (relative risk 3.3 [95% CI 1.0-10.4], P=0.04), but not females (P=0.63). Neither BMI  ≥ 95th percentile nor waist circumference>95th percentile was significant.

CONCLUSIONS

Children and youth with NC>95th percentile for age and sex have significantly increased risk of OSA. This effect is significant in males ≥ 12 years, whereas BMI is not. NC percentile may be an additional screening tool for OSA in children and youth.

[Obstructive sleep apnea in women]

The prevalence of sleep disturbances and their symptomatic manifestations may be different in men and women. Women with obstructive sleep apnea are less likely to be diagnosed with sleep apnea compared to men, probably due to atypical symptoms such as morning headaches, symptoms of depression and daytime fatigue. There is a great importance of diagnosis and treatment of sleep disorders regarding quality of life, co-morbidity and mortality in both genders.

Differences in associations between visceral fat accumulation and obstructive sleep apnea by sex

RATIONALE

The difference in mortality from obstructive sleep apnea (OSA) by sex is an important issue. Visceral fat, a significant risk factor for cardiovascular disease, was reported to be closely related to OSA.

OBJECTIVES

To assess the different associations between OSA and visceral fat area (VFA) by sex, which might account for the different prognosis in men and women with OSA.

METHODS

Participants were 271 men and 100 women consecutively hospitalized for examination of OSA from October 2008 to December 2010. Among the 371 participants, relationships were analyzed between fat areas by computed tomography, comorbidity, polysomnographic data, arterial blood gas, pulmonary function, and venous blood data. Multiple regression analyses were performed to identify variables independently associated with VFA and subcutaneous fat area for each sex.

MEASUREMENTS AND MAIN RESULTS

Despite similar body mass index (BMI) and waist circumference, men had larger VFA, more severe OSA, and more severe dyslipidemia than women. Multiple regression analyses revealed that in men, not only age and BMI but also minimal oxygen saturation (contribution rate [R(2)], 4.6%) during sleep, and alveolar-arterial oxygen difference (R(2) = 7.6%) were independently associated with VFA. Conversely, VFA was associated only with BMI in women.

CONCLUSIONS

Only in men was OSA independently associated with VFA. The lesser associations between OSA and visceral fat in women might account for the lower impact of OSA on cardiovascular disease or mortality in women.

Does neck-to-waist ratio predict obstructive sleep apnea in children?

OBJECTIVES

Central adiposity and large neck circumference are associated with obstructive sleep apnea (OSA) in adults but have not been evaluated in children as predictors of OSA. Study objectives were to determine whether (1) anthropometric measures including neck-to-waist ratio are associated with OSA in older children; (2) body fat distribution, measured by neck-to-waist ratio, is predictive of OSA in overweight/obese children.

METHODS

Cross-sectional study involving children 7-18 years scheduled to undergo polysomnography at a tertiary care children's hospital. OSA was defined as total apnea-hypopnea index > 5 events/h and/or obstructive apnea index > 1 event/h. Recursive partitioning was used to select candidate predictors of OSA from: age, sex, height and weight percentile, body mass index (BMI) z-score, neck-to-waist ratio, tonsil size, and Mallampati score. These were then evaluated using log binomial models and receiver operator characteristic analysis.

RESULTS

Two hundred twenty-two participants were included; 133 (60%) were overweight/obese, 121 (55%) male,47 (21%) had OSA. Neck-to-waist ratio (relative risk [RR] 1.97 per 0.1 units, 95% CI 1.48 to 2.84) and BMI z-score (RR 1.63 per unit, 95% CI 1.30 to 2.05) were identified as independent predictors of OSA. Considering only overweight/obese children, neck-to-waist ratio (RR 2.16 per 0.1 units, 95% CI 1.79 to 2.59) and BMI z-score (RR 2.02 per unit, 95% CI 1.25 to 3.26) also independently predicted OSA. However, in children not overweight/obese, these variables were not predictive of OSA.

CONCLUSIONS

Neck-to-waist ratio, an index of body fat distribution, predicts OSA in older children and youth, especially in those who were overweight/obese.

Positive airway pressure in patients with coronary artery disease and obstructive sleep apnea syndrome

AIMS

We designed a prospective nonrandomized study aiming at assessing the impact of continuous positive airway pressure (CPAP) after a new diagnosis of obstructive sleep apnea syndrome (OSAS) in patients with coronary artery disease (CAD).

METHODS

Consecutive patients referred to coronary angiography underwent an overnight sleep study during their hospital stay. Among those with angiographically confirmed CAD and a new diagnosis of moderate or severe OSAS, we compared the 3-year major adverse cardiac or cerebrovascular event (MACCE)-free survival stratified by CPAP at discharge.

RESULTS

Of 496 patients undergoing an overnight sleep study, 129 had angiographically confirmed CAD and presented with moderate or severe OSAS. The incidence of 3-year MACCE was significantly lower in the CPAP-treated group (n = 17) than in the untreated group (n = 112; 12 vs. 44%, P = 0.02). After adjusting for differences in baseline characteristics, CPAP was significantly associated with a decreased risk of MACCE [adjusted hazard ratio 0.18, 95% confidence interval (CI) 0.04-0.78, P = 0.02]. Among men, CPAP was associated with a significant 3-year risk reduction in MACCE (adjusted hazard ratio 0.12, 95% CI 0.02-0.87, P = 0.04), whereas no significant benefit of CPAP was seen in women (adjusted hazard ratio 2.1, 95% CI 0.10-41.6, P = 0.63). The statistical interaction between CPAP and sex trended to be significant (adjusted P for interaction = 0.10).

CONCLUSION

In patients with OSAS and CAD, the initiation of CPAP is associated with a significant reduction in MACCE compared with patients left untreated.

Major factors affecting severity of obstructive sleep apnea

Computed tomography (CT) has become a common method for evaluating obstructive sleep apnea (OSA). The aim of this study was to analyze the relationships between CT parameters and clinical parameters in OSA patients to determine major factors affecting the severity of OSA. The records of 128 consecutive snoring patients (98 males, 30 females) diagnosed with OSA were retrospectively reviewed. Polysomnography was performed for each patient. On CT scans, airway areas were measured at the level of the hard palate, the soft palate, and the base of the tongue. Polysomnographic parameters were compared by gender and age using the Mann-Whitney U test. Pearson's correlation coefficient was used to analyze relationships between variables and the AHI in each age group. The women were significantly older than the men (p < 0.01). The AHI and apnea index were significantly higher in men than in women. Stage 1 sleep and rapid eye movement sleep were more frequent in men than in women. The area at the base of the tongue was significantly smaller in women than in men (p = 0.027). In the 50-60 age group, the AHI was significantly higher in men (41.47 ± 19.67) than in women (17.14 ± 15.63) (p = 0.001). OSA severity varies with age, gender, and upper airway area. The OSA prognosis could be improved by evaluating the major factors and treating OSA patients according to epidemiological characteristics and anatomical structures.

The associations between anthropometric indices and obstructive sleep apnea in a Korean population

BACKGROUND

Obesity is a major risk factor for the development of obstructive sleep apnea (OSA). Although clinical and epidemiological studies have shown that OSA and obesity are strongly associated, few Asian studies have examined the associations between anthropometric obesity indices and OSA, especially in the Korean population. The purpose of this study was to evaluate the influence of anthropometric obesity indices on OSA in a Korean population.

METHODS

Anthropometric indices, including neck circumference, waist circumference, and body mass index, were assessed in 383 consecutive subjects with suspected OSA.

RESULTS

Of the 383 subjects assessed, 316 (82.5%) were diagnosed with OSA. Neck circumference (r = 0.518), waist circumference (r = 0.570), and body mass index (r = 0.512) were correlated with the apnea-hypopnea index (p<0.001, for all). After adjusting for age, sex, alcohol consumption, and smoking, a logistic regression model showed that neck circumference [odds ratio (OR), 1.414; p<0.001)], waist circumference (OR, 1.114; p<0.001), and body mass index (OR, 1.364; p<0.001) were associated with OSA. The linear regression model showed that neck circumference (β = 3.748, p<0.001), waist circumference (β = 1.272, p<0.001), and body mass index (β = 3.082, p<0.001) were associated with apnea-hypopnea index. The cut-off values for predicting OSA were determined as 34.5 cm for neck circumference, 76.5 cm for waist circumference, and 23.05 kg/m2 for body mass index for females, and 38.75 cm for neck circumference, 88.5 cm for waist circumference, and 24.95 kg/m2 for body mass index for males.

CONCLUSION

Increased anthropometric indices were significantly associated with the presence and severity of OSA in a Korean population. In addition, this study demonstrated the cut-off values for body mass index, waist circumference, and neck circumference for increased OSA risk.

Cephalometric and anthropometric data of obstructive apnea in different age groups

INTRODUCTION

Patients with obstructive sleep apnea syndrome usually present with changes in upper airway morphology and/or body fat distribution, which may occur throughout life and increase the severity of obstructive sleep apnea syndrome with age.

OBJECTIVE

To correlate cephalometric and anthropometric measures with obstructive sleep apnea syndrome severity in different age groups.

METHODS

A retrospective study of cephalometric and anthropometric measures of 102 patients with obstructive sleep apnea syndrome was analyzed. Patients were divided into three age groups (≥20 and <40 years, ≥40 and <60 years, and ≥60 years). Pearson's correlation was performed for these measures with the apnea-hypopnea index in the full sample, and subsequently by age group.

RESULTS

The cephalometric measures MP-H (distance between the mandibular plane and the hyoid bone) and PNS-P (distance between the posterior nasal spine and the tip of the soft palate) and the neck and waist circumferences showed a statistically significant correlation with apnea-hypopnea index in both the full sample and in the ≥40 and <60 years age group. These variables did not show any significant correlation with the other two age groups (<40 and ≥60 years).

CONCLUSION

Cephalometric measurements MP-H and PNS-P and cervical and waist circumferences correlated with obstructive sleep apnea syndrome severity in patients in the ≥40 and <60 age group.

Chronic intermittent hypoxia alters neurotransmission from lateral paragigantocellular nucleus to parasympathetic cardiac neurons in the brain stem

Patients with sleep-related disorders, including obstructive sleep apnea (OSA), have an increased risk of cardiovascular diseases. OSA events are more severe in rapid eye movement (REM) sleep. REM sleep further increases the risk of adverse cardiovascular events by diminishing cardioprotective parasympathetic activity. The mechanisms underlying REM sleep-related reduction in parasympathetic activity likely include activation of inhibitory input to cardiac vagal neurons (CVNs) in the brain stem originating from the lateral paragigantocellular nucleus (LPGi), a nucleus that plays a role in REM sleep control. This study tests the hypothesis that chronic intermittent hypoxia and hypercapnia (CIHH), an animal model of OSA, inhibits CVNs because of exaggeration of the GABAergic pathway from the LPGi to CVNs. GABAergic neurotransmission to CVNs evoked by electrical stimulation of the LPGi was examined with whole cell patch-clamp recordings in an in vitro brain slice preparation in rats exposed to CIHH and control rats. GABAergic synaptic events were enhanced after 4-wk CIHH in both male and female rats, to a greater degree in males. Acute hypoxia and hypercapnia (H/H) reversibly diminished the LPGi-evoked GABAergic neurotransmission to CVNs. However, GABAergic synaptic events were enhanced after acute H/H in CIHH male animals. Orexin-A elicited a reversible inhibition of LPGi-evoked GABAergic currents in control animals but evoked no significant changes in CIHH male rats. In conclusion, exaggerated inhibitory neurotransmission from the LPGi to CVNs in CIHH animals would reduce cardioprotective parasympathetic activity and enhance the risk of adverse cardiovascular events.

Obstructive sleep apnea-hypopnea results in significant variations in cerebral hemodynamics detected by diffuse optical spectroscopies

The objective of this study was to adapt a novel near-infrared diffuse correlation spectroscopy (DCS) flow-oximeter for simultaneous and continuous monitoring of relative changes in cerebral blood flow (rCBF) and cerebral oxygenation (i.e. oxygenated/deoxygenated/total hemoglobin concentration: Δ[HbO2]/Δ[Hb]/ΔTHC) during overnight nocturnal polysomnography (NPSG) diagnostic test for obstructive sleep apnea-hypopnea (OSAH). A fiber-optic probe was fixed on subject's frontal head and connected to the DCS flow-oximeter through a custom-designed fiber-optic connector, which allowed us to easily connect/detach the optical probe from the device when the subject went to bathroom. To minimize the disturbance to the subject, the DCS flow-oximeter was remotely operated by a desktop located in the control room. The results showed that apneic events caused significant variations in rCBF and ΔTHC. Moreover, the degrees of variations in all measured cerebral variables were significantly correlated with the severity of OSAH as determined by the apnea-hypopnea index (AHI), demonstrating the OSAH influence on both CBF and cerebral oxygenation. Large variations in arterial blood oxygen saturation (SaO2) were also found during OSAH. Since frequent variations/disturbances in cerebral hemodynamics may adversely impact brain function, future study will investigate the correlations between these cerebral variations and functional impairments for better understanding of OSAH pathophysiology.