Genetics of the apnea hypopnea index in Caucasians and African Americans: I. Segregation analysis

A multicenter study on the prevalence of adults and children seeking orthodontic treatment at high risk of obstructive sleep apnea

OBJECTIVE

To investigate the prevalence of adults and children seeking orthodontic treatment at high risk of obstructive sleep apnea (OSA) and pediatric OSA (POSA) and its association with demographic variables.

METHODS

One hundred-eleven adults and 105 children were consecutively recruited from three centers. The Epworth Sleepiness Scale (ESS) and ESS for Children and Adolescents were used for Risk stratifications for OSA and POSA.

RESULTS

The prevalence of patients seeking orthodontic treatment at high risk of OSA/POSA was 27.8%, where 26.1% were adults, and 29.5% were children. High risk for OSA/POSA was not associated with gender, ethnicity, age, Body Mass Index, or neck circumference.

CONCLUSION

Approximately 26% of adults and 30% of children seeking orthodontic care were at high risk for OSA and POSA. Screening for OSA and POSA among adults and children seeking orthodontic treatment is imperative.

Polysomnographic Characteristics of Snoring Children: A Familial Study of Obstructive Sleep Apnea Syndrome

BACKGROUND AND OBJECTIVES

Available evidence suggests a familial basis for OSA. The aim of the present study was to assess the potential influences of parental OSA in predicting the diagnosis and severity of OSA in snoring children.

METHODS

Observational study, we prospectively enrolled 84 children and their parents. A complete nocturnal polysomnography was performed. Children were categorized into 3 severity groups according to the apnea-hypopnea index (AHI<1h^-1, AHI≥1h^-1 to AHI<5h^-1, and AHI≥5h^-1). Adults were grouped according two criteria (AHI≥5h^-1 and ≥10h^-1).

RESULTS

There were no significant differences in age, gender, BMI and BMI z-score among groups. Among the children, 54.7% had an AHI≥1h^-1 and 21.4% had an AHI≥5h^-1. Overall, we observed that 60.7% of fathers and 23.8% of mothers of our population had OSA (AHI≥5h^-1). The prevalence of fathers with OSA increases with the children's severity (83% in the group of children with moderate-severe OSA, p=0.035). The odds of having moderate-severe pediatric OSA (AHI≥5h^-1) were more than 4 times higher among children with a father with AHI≥5h^-1 (OR: 4.92, 95% CI: 1.27-19.06; p=0.021). There was no evidence of any maternal influence on OSA severity among the children studied.

CONCLUSIONS

Our findings suggest a high prevalence of OSA among the family members studied with an increased association of childhood OSA with paternal OSA. Prediction of OSA risk among children can be significantly improved by adding data on paternal OSA status.

Sleep apnea in women veterans: results of a national survey of VA health care users

STUDY OBJECTIVES

The goals of this study were to estimate rates of undiagnosed, diagnosed, and treated sleep apnea in women veterans and to identify factors associated with diagnosis and treatment of sleep apnea in this population.

METHODS

A large nationwide postal survey was sent to a random sample of 4,000 women veterans who had received health care at a Veterans Health Administration (VA) facility in the previous 6 months. A total of 1,498 surveys were completed. Survey items used for the current analyses included: demographics; sleep apnea risk, diagnostic status, and treatment; symptoms of other sleep disorders (eg, insomnia); mental health symptoms; and comorbidities.

RESULTS

Among responders, 13% of women reported a prior sleep apnea diagnosis. Among women who reported a diagnosis of sleep apnea, 65% reported using positive airway pressure therapy. A sleep apnea diagnosis was associated with older age, higher BMI, non-Hispanic African American/Black racial/ethnic identity, being unemployed, other sleep disorder symptoms (eg, insomnia), depression and post-traumatic stress disorder symptoms, and multimorbidity. Among women without a sleep apnea diagnosis, 43% scored as "high risk" on the STOP (snoring, tiredness, observed apneas, blood pressure) questionnaire. High risk scores were associated with older age, higher BMI, African American/Black identity, other sleep disorder symptoms (eg, insomnia), mental health symptoms, and multimorbidity. Only BMI differed between women using vs not using positive airway pressure therapy.

CONCLUSIONS

Women veterans with diagnosed sleep apnea were commonly treated with positive airway pressure therapy, which is standard first-line treatment; however, many undiagnosed women were at high risk. Efforts to increase screening, diagnosis, and treatment of sleep apnea in women with comorbid mental and physical health conditions are needed.

Intermediate phenotypes of childhood obstructive sleep apnea

An intermediate phenotype of a disease is a trait in the path of pathogenesis from genetic predisposition to disease manifestation. Identifying intermediate phenotypes with high heritability is helpful in delineating the genetics of a disorder. In this study, we aimed to examine various traits with regards to obesity, cardiovascular risk and upper airway structure to identify potential intermediate phenotypes of childhood obstructive sleep apnea (OSA). Children aged between 6 and 18 years and their parents and siblings were recruited. All subjects underwent anthropometric measurements, cardiovascular risk assessment, sonographic measurement of lateral parapharyngeal wall (LPW) thickness, X-ray cephalometry and overnight polysomnography. A total of 34 phenotypes were examined. One hundred and one families consisting of 127 children (46 overweight) and 198 adults (84 overweight) were recruited. Heritability of obstructive apnea-hypopnea index (OAHI) was significant in overweight (h²  = 0.54) but not normal-weight individuals (h²  = 0.12). LPW thickness (h²  = 0.68) and resting blood pressure (h²  = 0.36 and 0.43 for systolic blood pressure [SBP] and diastolic blood pressure [DBP], respectively) were significantly heritable and associated with OAHI. Moreover, these traits were found to have shared genetic variance with OAHI in the overweight subgroup. Hyoid bone position also had significant heritability (h²  = 0.55) and association with OAHI but genetic correlation with OSA severity was not demonstrated. These findings suggest that LPW thickness and resting blood pressure are possible intermediate phenotypes of OSA independent of body mass index, especially in overweight patients. Identifying genes relevant to these phenotypes may help to elucidate the genetic susceptibility of OSA.

Sleep and the aging brain. A multifaceted approach

In the current review we provide a theoretical background on studies examining the association between sleep and brain function. We focus on the association between sleep and cognitive performance, cognitive changes over time and incident dementia as well. We then present some data on the link between sleep and subjective cognitive complaints, in participants without any objective clinical cognitive decline. We conclude with investigating the association between sleep and brain biomarkers, by highlighting the importance of specific genes and specific brain regions' morphometry. The role of sleep is vital in maintaining a healthy aging brain, and multiple factors should be taken under account when investigating this association.

Polysomnographic Characteristics of Snoring Children: A Familial Study of Obstructive Sleep Apnea Syndrome

BACKGROUND AND OBJECTIVES

Available evidence suggests a familial basis for OSA. The aim of the present study was to assess the potential influences of parental OSA in predicting the diagnosis and severity of OSA in snoring children.

METHODS

Observational study, we prospectively enrolled 84 children and their parents. A complete nocturnal polysomnography was performed. Children were categorized into 3 severity groups according to the apnea-hypopnea index (AHI<1h^-1, AHI≥1h^-1 to AHI<5h^-1, and AHI≥5h^-1). Adults were grouped according two criteria (AHI≥5h^-1 and ≥10h^-1).

RESULTS

There were no significant differences in age, gender, BMI and BMI z-score among groups. Among the children, 54.7% had an AHI≥1h^-1 and 21.4% had an AHI≥5h^-1. Overall, we observed that 60.7% of fathers and 23.8% of mothers of our population had OSA (AHI≥5h^-1). The prevalence of fathers with OSA increases with the children's severity (83% in the group of children with moderate-severe OSA, p=0.035). The odds of having moderate-severe pediatric OSA (AHI≥5h^-1) were more than 4 times higher among children with a father with AHI≥5h^-1 (OR: 4.92, 95% CI: 1.27-19.06; p=0.021). There was no evidence of any maternal influence on OSA severity among the children studied.

CONCLUSIONS

Our findings suggest a high prevalence of OSA among the family members studied with an increased association of childhood OSA with paternal OSA. Prediction of OSA risk among children can be significantly improved by adding data on paternal OSA status.

More Than the Sum of the Respiratory Events: Personalized Medicine Approaches for Obstructive Sleep Apnea

Traditionally, the presence and severity of obstructive sleep apnea (OSA) have been defined by the apnea-hypopnea index (AHI). Continuous positive airway pressure is generally first-line therapy despite low adherence, because it reliably reduces the AHI when used, and the response to other therapies is variable. However, there is growing appreciation that the underlying etiology (i.e., endotype) and clinical manifestation (i.e., phenotype) of OSA in an individual are not well described by the AHI. We define and review the important progress made in understanding and measuring physiological mechanisms (or endotypes) that help define subtypes of OSA and identify the potential use of genetics to further refine disease classification. This more detailed understanding of OSA pathogenesis should influence clinical treatment decisions as well as help inform research priorities and clinical study design. In short, treatments could be individualized on the basis of the underlying cause of OSA; patients could better understand which symptoms and outcomes will respond to OSA treatment and by how much; and researchers could select populations most likely to benefit from specific treatment approaches for OSA.

The prevalence of obstructive sleep apnea in patients with atrial fibrillation

BACKGROUND

Obstructive sleep apnea (OSA) is a systemic disorder associated with significant cardiovascular complications. OSA may play a role in the initiation and worsening of atrial fibrillation (AF). This study aimed to determine the prevalence and clinical predictors of OSA in patients with AF.

HYPOTHESIS

OSA is underdiagnosed in a large number of patients with AF and may not be predicted by conventional clinical indices.

METHODS

Consecutive nonselected patients with AF were recruited from different arrhythmia clinics in Toronto, Ontario, Canada. Patients with previous diagnosis and/or treatment of OSA were excluded. Patients underwent 2 consecutive nights of ambulatory sleep testing with full electroencephalogram recording. OSA was defined as an Apnea-Hypopnea Index (AHI) score ≥ 5 per hour of sleep.

RESULTS

123 patients with AF were recruited, with 100 patients included in the final analysis. OSA was detected in 85% of these patients. 27% of patients with normal overall AHI had an increased AHI during rapid eye movement sleep. Only age and male sex were independent predictors of the presence of OSA in these patients.

CONCLUSIONS

OSA is common and often undetected in patients with AF, especially in nonobese and/or female patients. Patients may have a normal overall AHI but an abnormal AHI during rapid eye movement sleep. The clinical relevance and therapeutic implications in this subgroup should be further investigated. The clinical features of OSA are not reliable predictors of OSA in patients with AF. A low threshold for detection of OSA, with sleep studies, in these patients may be merited.

Tailored Behavioral Intervention Among Blacks With Metabolic Syndrome and Sleep Apnea: Results of the MetSO Trial

Study Objectives

To assess effectiveness of a culturally and linguistically tailored telephone-delivered intervention to increase adherence to physician-recommended evaluation and treatment of obstructive sleep apnea (OSA) among blacks.

Methods

In a two-arm randomized controlled trial, we evaluated effectiveness of the tailored intervention among blacks with metabolic syndrome, relative to those in an attention control arm (n = 380; mean age = 58 ± 13; female = 71%). The intervention was designed to enhance adherence using culturally and linguistically tailored OSA health messages delivered by a trained health educator based on patients' readiness to change and unique barriers preventing desired behavior changes.

Results

Analysis showed 69.4% of the patients in the intervention arm attended initial consultation with a sleep specialist, compared to 36.7% in the control arm; 74.7% of those in the intervention arm and 66.7% in the control arm completed diagnostic evaluation; and 86.4% in the intervention arm and 88.9% in the control arm adhered to PAP treatment based on subjective report. Logistic regression analyses adjusting for sociodemographic factors indicated patients in the intervention arm were 3.17 times more likely to attend initial consultation, compared to those in the control arm. Adjusted models revealed no significant differences between the two arms regarding adherence to OSA evaluation or treatment.

Conclusion

The intervention was successful in promoting importance of sleep consultation and evaluation of OSA among blacks, while there was no significant group difference in laboratory-based evaluation and treatment adherence rates. It seems that the fundamental barrier to OSA care in that population may be the importance of seeking OSA care.

Hypertension and obstructive sleep apnea

Obstructive sleep apnea (OSA) is a major modifiable risk factor of hypertension and hypertensive patients with OSA are at increased risk for cardiovascular diseases. A substantial number of studies have revealed that OSA and hypertension have synergistic effects on the cardiovascular system and, therefore, it is clinically important and relevant to increase our understanding of the pathophysiological interactions between OSA and hypertension. In our present review, after briefly reviewing the characteristics and pathophysiological effects of OSA, we focus on the current understanding of OSA-associated hypertension, the potential approaches for treatment of OSA and the effect of OSA treatment on hypertension management. We hope our present review will shed light for future studies that investigate effective therapeutic strategies to simultaneously improve the management of OSA and hypertension.

Apolipoprotein E ɛ2/ɛ3/ɛ4 variant in association with obstructive sleep apnoea and lipid profile: A meta-analysis

Objective

A meta-analysis of the association between haplotypical variants of the apolipoprotein E (APOE) gene (ɛ2/ɛ3/ɛ4) and obstructive sleep apnoea (OSA) risk and changes in lipid profile.

Methods

Electronic databases were searched to retrieve articles that provided data on APOE gene ɛ2/ɛ3/ɛ4 variants in patients with OSA and healthy controls. Data were extracted from eligible articles and statistical analyses were performed.

Results

The meta-analysis included 14 articles involving 19 study populations (3198 patients and 6031 controls). There was no significant association between the presence of the ɛ4 allele and OSA risk. The presence of ɛ4 was associated with significantly increased total cholesterol and decreased high-density lipoprotein cholesterol, compared with ɛ4 allele negative individuals. There was a low probability of publication bias but significant heterogeneity.

Conclusions

There was no association between APOE ɛ2/ɛ3/ɛ4 and OSA susceptibility. The presence of APOE ɛ4 was associated with changes in lipid profile.

Differential increase in prevalence estimates of inadequate sleep among black and white Americans

BACKGROUND

The National Health Interview Survey (NHIS) was used to ascertain whether increases in inadequate sleep differentially affected black and white Americans. We tested the hypothesis that prevalence estimates of inadequate sleep were consistently greater among blacks, and that temporal changes have affected these two strata differentially.

METHODS

NHIS is an ongoing cross-sectional study of non-institutionalized US adults (≥18 years) providing socio-demographic, health risk, and medical factors. Sleep duration was coded as very short sleep [VSS] (<5 h), short sleep [SS] (5-6 h), or long sleep [LS] (>8 h), referenced to 7-8 h sleepers. Analyses adjusted for NHIS' complex sampling design using SAS-callable SUDAAN.

RESULTS

Among whites, the prevalence of VSS increased by 53% (1.5% to 2.3%) from 1977 to 2009 and the prevalence of SS increased by 32% (19.3% to 25.4 %); prevalence of LS decreased by 30% (11.2% to 7.8%). Among blacks, the prevalence of VSS increased by 21% (3.3% to 4.0%) and the prevalence of SS increased by 37% (24.6 % to 33.7%); prevalence of LS decreased by 42% (16.1% to 9.4%). Adjusted multinomial regression analysis showed that odds of reporting inadequate sleep for whites were: VSS (OR = 1.40, 95% CI = 1.13-1.74, p < 0.001), SS (OR = 1.34, 95 % CI = 1.25-1.44, p < 0.001), and LS (OR = 0.94, 95% CI = 0.85-1.05, NS). For blacks, estimates were: VSS (OR = 0.83, 95% CI = 0.60-1.40, NS), SS (OR = 1.21, 95% CI = 1.05-1.50, p < 0.001), and LS (OR = 0.84, 95% CI = 0.64-1.08, NS).

CONCLUSIONS

Blacks and whites are characteristically different regarding the prevalence of inadequate sleep over the years. Temporal changes in estimates of inadequate sleep seem dependent upon individuals' race/ethnicity.

Examining the association between Apolipoprotein E (APOE) and self-reported sleep disturbances in non-demented older adults

We aimed to examine the association between Apolipoprotein E (APOE) and sleep disturbances. This is a cross-sectional study, from the Washington Heights-Inwood Community Aging Project (WHICAP). A total of 1944 non-demented older adults took part in the study. Sleep dysfunction was measured using sleep categories derived from the Medical Outcomes Study Sleep Scale. Genetic association between APOE-ϵ4 genotype and sleep disturbances was assessed using unadjusted linear regression models. Secondary analyses were conducted adjusting for age, sex, education, ethnicity and body mass index (BMI). In the unadjusted model, individuals carrying the APOE-ϵ4 allele showed lower levels of snoring (β=-0.02, SE=0.01, p=0.010) and sleep apnea (β=-0.01, SE=0.01, p=0.037) when compared to non-ϵ4 carriers. After covariates' adjustment, ϵ4 carriers demonstrated stronger association with lower levels of both snoring (β=-0.02, SE=0.01, p=0.006), and sleep apnea (β=-0.01, SE=0.01, p=0.018). Our results suggest that APOE-ϵ4 is associated with decreased problems in snoring and sleep apnea, in non-demented older adults.

Racial/Ethnic Differences in Sleep Disturbances: The Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVES

There is limited research on racial/ethnic variation in sleep disturbances. This study aimed to quantify the distributions of objectively measured sleep disordered breathing (SDB), short sleep duration, poor sleep quality, and self-reported sleep disturbances (e.g., insomnia) across racial/ethnic groups.

DESIGN

Cross-sectional study.

SETTING

Six US communities.

PARTICIPANTS

Racially/ethnically diverse men and women aged 54-93 y in the Multi-Ethnic Study of Atherosclerosis Sleep Cohort (n = 2,230).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Information from polysomnography-measured SDB, actigraphy-measured sleep duration and quality, and self-reported daytime sleepiness were obtained between 2010 and 2013. Overall, 15.0% of individuals had severe SDB (apnea-hypopnea index [AHI] ≥ 30); 30.9% short sleep duration (< 6 h); 6.5% poor sleep quality (sleep efficiency < 85%); and 13.9% had daytime sleepiness. Compared with Whites, Blacks had higher odds of sleep apnea syndrome (AHI ≥ 5 plus sleepiness) (sex-, age-, and study site-adjusted odds ratio [OR] = 1.78, 95% confidence interval [CI]: 1.20, 2.63), short sleep (OR = 4.95, 95% CI: 3.56, 6.90), poor sleep quality (OR = 1.57, 95% CI: 1.00, 2.48), and daytime sleepiness (OR = 1.89, 95% CI: 1.38, 2.60). Hispanics and Chinese had higher odds of SDB and short sleep than Whites. Among non-obese individuals, Chinese had the highest odds of SDB compared to Whites. Only 7.4% to 16.2% of individuals with an AHI ≥ 15 reported a prior diagnosis of sleep apnea.

CONCLUSIONS

Sleep disturbances are prevalent among middle-aged and older adults, and vary by race/ethnicity, sex, and obesity status. The high prevalence of sleep disturbances and undiagnosed sleep apnea among racial/ethnic minorities may contribute to health disparities.

Characteristics of children under 2 years of age undergoing tonsillectomy for upper airway obstruction

INTRODUCTION

To study characteristics of children less than 2 years who underwent a tonsillectomy for sleep disordered breathing (SDB) or obstructive sleep apnea (OSA) to assess for factors associated with requesting a preoperative polysomnogram (PSG) and to identify predictors of upper airway obstruction in this group.

MATERIALS AND METHODS

A retrospective chart review of children under 2 years who underwent a tonsillectomy over a 7-year period at a tertiary care pediatric hospital was undertaken. Patient demographics, characteristics and polysomnography results, when applicable, were collected. In order to determine if the gathered demographics of our cohort differed from the non-surgical population, we compared our data with available Colorado data for each variable. Children were stratified by OSA severity using their obstructive apnea-hypopnea index (OAHI).

RESULTS

197 (2.2%) of 9038 patients who underwent tonsillectomy for SDB or OSA were ≤ 24 months. The proportions of male, African-American, Hispanic, obese, underweight, premature, syndromic and daycare patients in our cohort were significantly different than in the general population. In a multivariate model, the odds of African-Americans having severe OSA were 12.5 times greater than the odds of Caucasians. The odds of patients with syndromes or craniofacial anomalies were 11 times greater (p < 0.0001), and the odds of patients in daycare were 2.2 times lower (p = 0.04) of undergoing a PSG before tonsillectomy. Weight did not influence polysomnogram requests.

CONCLUSIONS

In children under 2 years, ethnicity seems to be a predictor of OSA severity. African-American, prematurity, daycare and Down syndrome patients were significantly more represented in our study population. PSG is more likely to be requested for syndromic children.

Biomarkers associated with obstructive sleep apnea: A scoping review

The overall validity of biomarkers in the diagnosis of obstructive sleep apnea (OSA) remains unclear. We conducted a scoping review to provide assessments of biomarkers characteristics in the context of obstructive sleep apnea (OSA) and to identify gaps in the literature. A scoping review of studies in humans without age restriction that evaluated the potential diagnostic value of biological markers (blood, exhaled breath condensate, salivary, and urinary) in the OSA diagnosis was undertaken. Retained articles were those focused on the identification of biomarkers in subjects with OSA, the latter being confirmed with a full overnight or home-based polysomnography (PSG). Search strategies for six different databases were developed. The methodology of selected studies was classified using an adaptation of the evidence quality criteria from the American Academy of Pediatrics. Additionally the biomarkers were classified according to their potential clinical application. We identified 572 relevant studies, of which 117 met the inclusion criteria. Eighty-two studies were conducted in adults, 34 studies involved children, and one study had a sample composed of both adults and children. Most of the studies evaluated blood biomarkers. Potential diagnostic biomarkers were found in nine pediatric studies and in 58 adults studies. Only nine studies reported sensitivity and specificity, which varied substantially from 43% to 100%, and from 45% to 100%, respectively. Studies in adults have focused on the investigation of IL-6, TNF-α and hsCRP. There was no specific biomarker that was tested by a majority of authors in pediatric studies, and combinatorial urine biomarker approaches have shown preliminary promising results. In adults IL-6 and IL-10 seem to have a favorable potential to become a good biomarker to identify OSA.

Minority Breast Cancer Survivors: The Association between Race/Ethnicity, Objective Sleep Disturbances, and Physical and Psychological Symptoms

Background. Limited research has been conducted on the moderating effect of race/ethnicity on objective sleep disturbances in breast cancer survivors (BCSs). Objective. To explore racial/ethnic differences in objective sleep disturbances among BCSs and their relationship with self-reported symptoms. Intervention/Methods. Sleep disturbance and symptoms were measured using actigraphy for 72 hours and self-reported questionnaires, respectively, among 79 BCSs. Analysis of covariance, Pearson's correlation, and multivariate regression were used to analyze data. Results. Sixty (75.9%) participants listed their ethnicity as white, non-Hispanic and 19 (24.1%) as minority. Total sleep time was 395.9 minutes for white BCSs compared to 330.4 minutes for minority BCSs. Significant correlations were seen between sleep onset latency (SOL) and depression, SOL and fatigue, and sleep efficiency (SE) and fatigue among minority BCSs. Among white BCSs, significant correlations were seen between SE and pain and wake after sleep onset (WASO) and pain. The association between depression and SOL and fatigue and SOL appeared to be stronger in minority BCSs than white BCSs. Conclusions. Results indicate that white BCSs slept longer than minority BCSs, and race/ethnicity modified the effect of depression and fatigue on SOL, respectively. Implications for Practice. As part of survivorship care, race/ethnicity should be included as an essential component of comprehensive symptom assessments.

Telephone-delivered behavioral intervention among blacks with sleep apnea and metabolic syndrome: study protocol for a randomized controlled trial

Background

Lack of adherence to recommended treatment for obstructive sleep apnea remains an ongoing public health challenge. Despite evidence that continuous positive airway pressure (CPAP) is effective and improves overall quality of life, adherence with the use of CPAP in certain racial/ethnic groups, especially blacks, is suboptimal. Evidence indicates that the incidence and prevalence of obstructive sleep apnea are higher among blacks, relative to whites, and blacks are less likely to adhere to recommended treatment compared with other racial/ethnic groups.

Methods

Using a two-arm randomized controlled design, this study will evaluate the effectiveness of a culturally and linguistically tailored telephone-delivered intervention to promote adherence to physician-recommended sleep apnea assessment and treatment among blacks with metabolic syndrome, versus an attention-control arm. The intervention is designed to foster adherence to recommended sleep apnea care using the stages-of-change model. The intervention will be delivered entirely over the telephone. Participants in the intervention arm will receive 10 phone calls to address challenges and barriers to recommended care. Outcomes will be assessed at baseline, and at 6- and 12-months post-randomization.

Discussion

This tailored behavioral intervention will improve adherence to sleep apnea assessment and treatment among blacks with metabolic syndrome. We expect to demonstrate that this intervention modality is feasible in terms of time and cost and can be replicated in populations with similar racial/ethnic backgrounds.

Trial registration

The study is registered at clinicaltrials.gov NCT01946659 (February 2013)

Linking sleep duration and obesity among black and white US adults

AIMS

The effect of race/ethnicity on the risk of obesity associated with short or long sleep durations is largely unknown. This study assessed whether the sleep-obesity link differentially affects black and whites.

METHODS

Analysis was based on data obtained from 29,818 adult American respondents from the 2005 National Health Interview Survey, a cross-sectional household interview survey.

RESULTS

Multivariate-adjusted odds ratios for obesity associated with short sleep (≤6 h) among blacks and whites were 1.98 (95% CI: 1.69-2.30) and 1.20 (95% CI: 1.10-1.31), respectively, and with long sleep (≥9 h) for blacks and whites were 1.48 (95% CI: 1.14-1.93) and 0.77 (95% CI: 0.67-0.89), respectively (all p < 0.001).

CONCLUSION

Race/ethnicity may have significantly influenced the likelihood of reporting obesity associated with short and long sleep durations. Relative to white respondents, an excess of 78% of black respondents showed increased obesity odds associated with short sleep. Black long sleepers also showed increased odds for obesity, but white long sleepers may be at a reduced obesity risk.

Sleep in America: role of racial/ethnic differences

Sleep duration in America has gradually declined over the last four decades and appears to have reached a plateau for the last six years, with recent studies reporting that the population's current average sleep duration is approximately 6 h. In this paper, we examine epidemiologic and community-based data on sleep complaints reported by American adults, specifically addressing the role of race/ethnicity in the subjective report of sleep problems. Subjective and objective findings indicate that black (throughout the text, we use the term black in lieu of African American for there are instances where we refer to individuals with self-ascribed race/ethnicity as black, African American, African, or Caribbean American; the term white is used to denote individuals of European descent). Americans have higher rates of long (≥9 h) and short (≤5 h) sleep than their white counterparts, and this may mediate a higher risk of cardiovascular disease, obesity and diabetes among blacks. In addition, studies show mixed results on sleep complaints among blacks compared to those among other ethnicities. This paper explores factors that may contribute to racial/ethnic differences in sleep including intra-ethnic variation, cultural biases, genetics and psychosocial factors.

APOM and high-density lipoprotein cholesterol are associated with lung function and per cent emphysema

Chronic obstructive pulmonary disease (COPD) is linked to cardiovascular disease; however, there are few studies on the associations of cardiovascular genes with COPD. We assessed the association of lung function with 2100 genes selected for cardiovascular diseases among 20 077 European-Americans and 6900 African-Americans. We performed replication of significant loci in the other racial group and an independent consortium of Europeans, tested the associations of significant loci with per cent emphysema and examined gene expression in an independent sample. We then tested the association of a related lipid biomarker with forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio and per cent emphysema. We identified one new polymorphism for FEV1/FVC (rs805301) in European-Americans (p=1.3×10(-6)) and a second (rs707974) in the combined European-American and African-American analysis (p=1.38×10(-7)). Both single-nucleotide polymorphisms (SNPs) flank the gene for apolipoprotein M (APOM), a component of high-density lipoprotein (HDL) cholesterol. Both were replicated in an independent cohort. SNPs in a second gene related to apolipoprotein M and HDL, PCSK9, were associated with FEV1/FVC ratio among African-Americans. rs707974 was associated with per cent emphysema among European-Americans and African-Americans and APOM expression was related to FEV1/FVC ratio and per cent emphysema. Higher HDL levels were associated with lower FEV1/FVC ratio and greater per cent emphysema. These findings suggest a novel role for the apolipoprotein M/HDL pathway in the pathogenesis of COPD and emphysema.

Association of genetic loci with sleep apnea in European Americans and African-Americans: the Candidate Gene Association Resource (CARe)

Although obstructive sleep apnea (OSA) is known to have a strong familial basis, no genetic polymorphisms influencing apnea risk have been identified in cross-cohort analyses. We utilized the National Heart, Lung, and Blood Institute (NHLBI) Candidate Gene Association Resource (CARe) to identify sleep apnea susceptibility loci. Using a panel of 46,449 polymorphisms from roughly 2,100 candidate genes on a customized Illumina iSelect chip, we tested for association with the apnea hypopnea index (AHI) as well as moderate to severe OSA (AHI≥15) in 3,551 participants of the Cleveland Family Study and two cohorts participating in the Sleep Heart Health Study.

Among 647 African-Americans, rs11126184 in the pleckstrin (PLEK) gene was associated with OSA while rs7030789 in the lysophosphatidic acid receptor 1 (LPAR1) gene was associated with AHI using a chip-wide significance threshold of p-value<2×10⁻⁶. Among 2,904 individuals of European ancestry, rs1409986 in the prostaglandin E2 receptor (PTGER3) gene was significantly associated with OSA. Consistency of effects between rs7030789 and rs1409986 in LPAR1 and PTGER3 and apnea phenotypes were observed in independent clinic-based cohorts.

Novel genetic loci for apnea phenotypes were identified through the use of customized gene chips and meta-analyses of cohort data with replication in clinic-based samples. The identified SNPs all lie in genes associated with inflammation suggesting inflammation may play a role in OSA pathogenesis.

Transferability and fine-mapping of glucose and insulin quantitative trait loci across populations: CARe, the Candidate Gene Association Resource

AIMS/HYPOTHESIS

Hyperglycaemia disproportionately affects African-Americans (AfAs). We tested the transferability of 18 single-nucleotide polymorphisms (SNPs) associated with glycaemic traits identified in European ancestry (EuA) populations in 5,984 non-diabetic AfAs.

METHODS

We meta-analysed SNP associations with fasting glucose (FG) or insulin (FI) in AfAs from five cohorts in the Candidate Gene Association Resource. We: (1) calculated allele frequency differences, variations in linkage disequilibrium (LD), fixation indices (F(st)s) and integrated haplotype scores (iHSs); (2) tested EuA SNPs in AfAs; and (3) interrogated within ± 250 kb around each EuA SNP in AfAs.

RESULTS

Allele frequency differences ranged from 0.6% to 54%. F(st) exceeded 0.15 at 6/16 loci, indicating modest population differentiation. All iHSs were <2, suggesting no recent positive selection. For 18 SNPs, all directions of effect were the same and 95% CIs of association overlapped when comparing EuA with AfA. For 17 of 18 loci, at least one SNP was nominally associated with FG in AfAs. Four loci were significantly associated with FG (GCK, p = 5.8 × 10(-8); MTNR1B, p = 8.5 × 10(-9); and FADS1, p = 2.2 × 10(-4)) or FI (GCKR, p = 5.9 × 10(-4)). At GCK and MTNR1B the EuA and AfA SNPs represented the same signal, while at FADS1, and GCKR, the EuA and best AfA SNPs were weakly correlated (r(2) <0.2), suggesting allelic heterogeneity for association with FG at these loci.

CONCLUSIONS/INTERPRETATION

Few glycaemic SNPs showed strict evidence of transferability from EuA to AfAs. Four loci were significantly associated in both AfAs and those with EuA after accounting for varying LD across ancestral groups, with new signals emerging to aid fine-mapping.

Association of the 5-HT2A receptor gene polymorphisms with obstructive sleep apnea hypopnea syndrome in Chinese Han population

CONCLUSIONS

The -1438G/A polymorphism of 5-HT2A receptor gene may associate with obstructive sleep apnea hypopnea syndrome (OSAHS) in a Chinese Han population. Different genotypes of -1438G/A polymorphism may influence the ventilatory activity in response to hypoxia, and in turn the sleep breath status.

OBJECTIVE

This study was designed to assess the association of polymorphisms in all exons and promoter region of the 5-HT2A receptor gene with OSAHS in a Chinese Han population.

METHODS

A total of 315 subjects (210 patients and 105 controls) were included for genetic analyses of polymorphisms in all exons and promoter region of the 5-HT2A receptor gene.

RESULTS

Six single nucleoside polymorphism (SNP) sites were identified in the sequencing of the promoter and exons of the 5-HT2A receptor gene; however, genotypes and allele frequencies of the SNPs did not show significant differences between the patients and controls except the -1438G/A polymorphism. For SNP of -1438G/A, the A/A genotype was over-represented and the allele A was more frequent in the patients, while the G/A genotype was over-represented and the allele G was more frequent in the controls (p < 0.001, p = 0.005, respectively). In the patients, the A/A and G/A genotypes were over-represented in the subgroups with lowest nocturnal SaO(2) (LSaO(2)) ≤75% and LSaO(2) >75%, respectively (p = 0.006).

The association of race/ethnicity with objectively measured sleep characteristics in older men

This study examined the association between race/ethnicity and objectively measured sleep characteristics in a large sample of older men. Black men had significantly shorter total sleep time (6.1 hr vs. 6.4 hr), longer sleep latency (28.7 min vs. 21.9 min), lower sleep efficiency (80.6% vs. 83.4%), and less slow-wave sleep (4.9% vs. 8.8%) than White men, even after controlling for social status, comorbidities, body mass index, and sleep-disordered breathing. Hispanic men slept longer (6.7 hr) at night than Black (6.1 hr) and Asian American men (6.1 hr). This study supports significant variations in sleep characteristics in older men by race/ethnicity.

Ethnic differences in continuous positive airway pressure (CPAP) adherence in veterans with and without psychiatric disorders

Continuous positive airway pressure (CPAP) is a safe, effective treatment for sleep apnea, yet adherence is notoriously problematic. Vulnerable populations that may be at increased risk of sleep apnea include African Americans (AAs) and individuals with psychiatric disorders, yet little is known about whether such individuals are at increased risk of CPAP non-adherence. This study examined rates of CPAP adherence in a large sample of AA and Caucasian American (CA) military veterans with and without comorbid mental health disorders. AAs used CPAP less than CAs throughout the first 3 months of treatment. AAs with mental health diagnoses showed the lowest CPAP adherence; additional research is needed to identify factors that may be increasing the risk for CPAP non-adherence in these individuals.

Families with sleepwalking

BACKGROUND

Studies on families with sleepwalking are uncommonly published but can give further information on the phenotype of patients with chronic sleepwalking.

SUBJECTS AND METHODS

Out of 51 individuals referred for chronic sleepwalking during a 5-year period, we obtained sufficient information on 7 families with direct relatives who reported sleepwalking with or without sleep terrors. Among 70 living direct family members, we obtained questionnaire responses from 50 subjects and identified 34 cases with a history of sleepwalking. Of the 50 subjects, 16 completed only questionnaires, while all the others also completed a clinical evaluation and nocturnal sleep recordings.

RESULTS

There was a positive history of sleepwalking on either the paternal or maternal side of the family over several generations in our 7 families. Thirty-three clinically evaluated subjects had evidence of sleep-disordered breathing (SDB), with associated craniofacial risk factors for SDB (particularly maxillary and/or mandibular deficiencies). There was a complete overlap with the report of parasomnias and the presence of SDB. In cases with current sleepwalking, treatment of SDB coincided with clear improvement of the parasomnia.

CONCLUSION

All of our subjects with parasomnias presented with familial traits considered as risk factors for SDB. These anatomical risk factors are present at birth and even subtle SDB can lead to sleep disruption and instability of NREM sleep. The question raised is: are factors leading to chronic sleep disruption the familial traits responsible for familial sleepwalking?

Candidate gene association resource (CARe): design, methods, and proof of concept

BACKGROUND

The National Heart, Lung, and Blood Institute's Candidate Gene Association Resource (CARe), a planned cross-cohort analysis of genetic variation in cardiovascular, pulmonary, hematologic, and sleep-related traits, comprises >40,000 participants representing 4 ethnic groups in 9 community-based cohorts. The goals of CARe include the discovery of new variants associated with traits using a candidate gene approach and the discovery of new variants using the genome-wide association mapping approach specifically in African Americans.

METHODS AND RESULTS

CARe has assembled DNA samples for >40,000 individuals self-identified as European American, African American, Hispanic, or Chinese American, with accompanying data on hundreds of phenotypes that have been standardized and deposited in the CARe Phenotype Database. All participants were genotyped for 7 single-nucleotide polymorphisms (SNPs) selected based on prior association evidence. We performed association analyses relating each of these SNPs to lipid traits, stratified by sex and ethnicity, and adjusted for age and age squared. In at least 2 of the ethnic groups, SNPs near CETP, LIPC, and LPL strongly replicated for association with high-density lipoprotein cholesterol concentrations, PCSK9 with low-density lipoprotein cholesterol levels, and LPL and APOA5 with serum triglycerides. Notably, some SNPs showed varying effect sizes and significance of association in different ethnic groups.

CONCLUSIONS

The CARe Pilot Study validates the operational framework for phenotype collection, SNP genotyping, and analytic pipeline of the CARe project and validates the planned candidate gene study of approximately 2000 biological candidate loci in all participants and genome-wide association study in approximately 8000 African American participants. CARe will serve as a valuable resource for the scientific community.

Polymorphisms in α- and β-Adrenergic Receptor Genes, Hypertension, and Obstructive Sleep Apnea: The Skaraborg Sleep Study

The sympathetic nervous system and the adrenergic receptors play an important role in regulation of blood pressure. This study explored the associations between functional polymorphisms of the α(2B)-, β(1)-, and β(2)-adrenergic receptor genes and obstructive sleep apnea (OSA) in hypertensive patients and hypertension in patients with OSA in a populationbased sample of 157 hypertensive patients and 181 healthy control subjects. Only the Arg389Gly polymorphism of the β(1)-adrenergic receptor gene was associated with increased risk for mild OSA in hypertensive patients (Arg/Arg versus Gly/Arg/Gly/Gly, 2.1, 95% CI, 1.02-4.7). Hypertensive men carrying the Arg389Arg genotype had higher crude and age-adjusted AHI than carriers of the Arg389Gly/Gly389Gly genotypes. When adjusted also for BMI this difference became borderline significant. This difference was not observed in women. The risk of hypertension in mild OSA was associated with increasing number of Arg-alleles (Arg/Arg OR 5.4, 95% CI 1.4-21.2).

Pathophysiology of sleep apnea

Sleep-induced apnea and disordered breathing refers to intermittent, cyclical cessations or reductions of airflow, with or without obstructions of the upper airway (OSA). In the presence of an anatomically compromised, collapsible airway, the sleep-induced loss of compensatory tonic input to the upper airway dilator muscle motor neurons leads to collapse of the pharyngeal airway. In turn, the ability of the sleeping subject to compensate for this airway obstruction will determine the degree of cycling of these events. Several of the classic neurotransmitters and a growing list of neuromodulators have now been identified that contribute to neurochemical regulation of pharyngeal motor neuron activity and airway patency. Limited progress has been made in developing pharmacotherapies with acceptable specificity for the treatment of sleep-induced airway obstruction. We review three types of major long-term sequelae to severe OSA that have been assessed in humans through use of continuous positive airway pressure (CPAP) treatment and in animal models via long-term intermittent hypoxemia (IH): 1) cardiovascular. The evidence is strongest to support daytime systemic hypertension as a consequence of severe OSA, with less conclusive effects on pulmonary hypertension, stroke, coronary artery disease, and cardiac arrhythmias. The underlying mechanisms mediating hypertension include enhanced chemoreceptor sensitivity causing excessive daytime sympathetic vasoconstrictor activity, combined with overproduction of superoxide ion and inflammatory effects on resistance vessels. 2) Insulin sensitivity and homeostasis of glucose regulation are negatively impacted by both intermittent hypoxemia and sleep disruption, but whether these influences of OSA are sufficient, independent of obesity, to contribute significantly to the "metabolic syndrome" remains unsettled. 3) Neurocognitive effects include daytime sleepiness and impaired memory and concentration. These effects reflect hypoxic-induced "neural injury." We discuss future research into understanding the pathophysiology of sleep apnea as a basis for uncovering newer forms of treatment of both the ventilatory disorder and its multiple sequelae.

Sleep duration and biomarkers of inflammation

INTRODUCTION

Extremes of sleep duration have been associated with adverse health outcomes. The mechanism is unclear but may be related to increased inflammation. We sought to assess the association between sleep duration and inflammatory biomarkers.

METHODS

A total of 614 individuals from the Cleveland Family Study completed questionnaires about sleep habits and underwent polysomnography. A morning fasting blood sample was assayed for 5 inflammatory cytokines.

RESULTS

In this cohort, mean (SD) habitual sleep duration based on self-report was 7.6 (1.6) h and mean sleep duration by polysomnography (PSG) on the night prior to blood sampling was 6.2 (1.3) h. After adjusting for obesity and apnea severity, each additional hour of habitual sleep duration was associated with an 8% increase in C-reactive protein (CRP) levels (P=0.004) and 7% increase in interleukin-6 (IL-6) levels (P=0.0003). These associations were independent of self-reported sleepiness. In contrast, PSG sleep duration was inversely associated with tumor necrosis factor alpha (TNFa) levels. For each hour reduction in sleep, TNFalpha levels increased by 8% on average (P=0.02). Sleep duration was not associated with IL-1 or IL-10.

CONCLUSIONS

Increases in habitual sleep durations are associated with elevations in CRP and IL-6 while reduced PSG sleep duration is associated with elevated TNFa levels. Activation of pro-inflammatory pathways may represent a mechanism by which extreme sleep habits affect health.

Obstructive sleep apnoea and its cardiovascular consequences

Obstructive sleep apnoea (OSA) is a common disorder in which repetitive apnoeas expose the cardiovascular system to cycles of hypoxia, exaggerated negative intrathoracic pressure, and arousals. These noxious stimuli can, in turn, depress myocardial contractility, activate the sympathetic nervous system, raise blood pressure, heart rate, and myocardial wall stress, depress parasympathetic activity, provoke oxidative stress and systemic inflammation, activate platelets, and impair vascular endothelial function. Epidemiological studies have shown significant independent associations between OSA and hypertension, coronary artery disease, arrhythmias, heart failure, and stroke. In randomised trials, treating OSA with continuous positive airway pressure lowered blood pressure, attenuated signs of early atherosclerosis, and, in patients with heart failure, improved cardiac function. Current data therefore suggest that OSA increases the risk of developing cardiovascular diseases, and that its treatment has the potential to diminish such risk. However, large-scale randomised trials are needed to determine, definitively, whether treating OSA improves cardiovascular outcomes.

Association study of serotonin transporter gene polymorphisms with obstructive sleep apnea syndrome in Chinese Han population

BACKGROUND

Since the serotonin (5-HT) is associated with circadian rhythm and breathing regulation, the serotonin transporter (5-HTT), which plays an important role in serotoninergic transmission, might be a strong candidate gene in the pathogenesis of obstructive sleep apnea syndrome (OSAS).

OBJECTIVE

To investigate the association of 5-HTT gene polymorphisms with OSAS and clinical characteristics.

METHODS

We genotyped the 5-HTT gene linked polymorphic region (5-HTTLPR) and a variable number of tandem repeats at intron 2 (STin2.VNTR) in 254 OSAS patients and 338 healthy controls in Chinese Han population.

RESULTS

In total sample, the 10-repeat allele of STin2.VNTR was significantly associated with OSAS (P = 0.007, OR = 1.72, 95% CI = 1.15-2.58), but no association was found in 5-HTTLPR. In male subjects, both polymorphisms showed significant association with OSAS (Allele L: P = 0.005, OR = 1.44, 95% CI = 1.11 to 1.87; Allele 10: P = 0.002, OR= 1.94, 95% CI = 1.26 to 3.00). Two haplotypes, S-12 and L-10, constructed by the above polymorphisms also revealed significant associations with OSAS (global P-values were 0.020 for total sample and 0.0006 for male subjects, respectively). Male patients carrying the haplotype S-12 showed a significantly lower apnea / hypopnea index (AHI), depressive factor, plasma 5-HT level and 5-hydroxyindolacetic acid (5-HIAA) levels, but higher episodic memory, when compared with non-S-12 carriers (P < 0.05). However, no significant differences were found in excessive daytime sleepiness or other psychological function across haplotype carriers (P > 0.05).

CONCLUSIONS

These findings support that 5-HTT gene may be involved in susceptibility to OSAS, especially with sex-dependent effect.

Obstructive sleep apnea syndrome in siblings: an 8-year Swedish follow-up study

BACKGROUND

Understanding the genetic transmission of obstructive sleep apnea syndrome (OSAS) will help clinicians identify patients at risk and offer opportunities for intervention and treatment at specialist clinics.

OBJECTIVE

To estimate familial risk of hospitalization for OSAS in the adult population of Sweden, and to determine if there are any differences by age and sex.

DESIGN, SETTING, AND PARTICIPANTS

Using the MigMed database at the Karolinska Institute, we divided the population of Sweden into sibling groups based on a shared mother and father and ascertained the presence or absence of a primary hospital diagnosis of OSAS in each individual during the follow-up period, 1997 to 2004. Individuals were categorized as having or not having a sibling with OSAS, based on the presence or absence of the disorder in at least 1 of their siblings. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were estimated for men and women with a sibling with OSAS, compared with men and women in the reference group (SIR = 1).

RESULTS

After accounting for socioeconomic status, age, geographic region, and period of diagnosis, men with at least 1 sibling who had OSAS had a SIR of 3.42 (95% CI, 2.18-5.36); the corresponding SIR in women was 3.25 (95% CI, 1.84-5.65).

CONCLUSIONS

Our results indicate that physicians should consider family history of OSAS when deciding whether to refer a patient for further sleep examinations.

Heritability of upper airway dimensions derived using acoustic pharyngometry

Acoustic pharyngometry represents a simple, quick noninvasive method of measuring upper airway dimensions, which are predictive of sleep apnoea risk. The aim of the present study was to assess the genetic basis of upper airway size as determined using pharyngometry. Participants in the Cleveland Family Study aged >14 yrs underwent three acoustic pharyngometric measurements. Variance component models adjusted for age and sex were used to estimate the heritability of pharyngometry-derived airway measures. A total of 568 out of 655 (87%) subjects provided pharyngometric curves of sufficient quality. Although African-Americans tended to show narrower airways compared with white subjects, heritability patterns were similar in these two groups. The minimum cross-sectional area exhibited a heritability of 0.34 in white subjects and 0.39 in African-Americans, suggesting that 30-40% of the total variance in this measure is explained by shared familial factors. Estimates were unchanged after adjustment for body mass index or neck circumference. In contrast, oropharyngeal length did not show significant heritability in either ethnic group. The minimum cross-sectional area of the oropharynx is a highly heritable trait, suggesting the presence of an underlying genetic basis. These findings demonstrate the potential utility of acoustic pharyngometry in dissecting the genetic basis of sleep apnoea.

Symptoms of obstructive sleep apnea in a Caribbean sample

Obstructive sleep apnea (OSA) is a prevalent sleep disorder that disproportionately affects blacks. While clinical and epidemiologic data indicate intraethnic differences in several medical diseases, little is known about whether OSA symptoms differ within the black ethnic group. We estimated the rate of OSA symptoms in a community-based sample of Caribbean-born black men and women. We also ascertained which sociodemographic and/or medical factors were associated with OSA risk. A total of 554 patients (mean age = 48.17 +/- 16.75 years) participated in the study; 55% were women. Data were collected in four primary-care clinics in Brooklyn, NY. A health educator explained the purpose of the study to interested patients and assisted consenting participants in completing questionnaires, which required 15 min to complete. Participants reporting habitual snoring, excessive daytime sleepiness, and sleep fragmentation were considered at high OSA risk. The rate of OSA symptoms was: snoring (45%), excessive daytime sleepiness (33%), and difficulty maintaining sleep (34%). Many reported falling asleep while watching television (47%) or while driving (14%). Based on logistic regression analysis, a history of heart disease was the most important predictor of the likelihood of expressing OSA symptoms, with a corresponding multivariate-adjusted odds ratio of 11 (95% confidence interval = 3.03-40.63). Findings suggest the need to investigate whether Caribbean-born blacks are at greater risk for developing OSA than African Americans and whites. Caribbean-born blacks with a history of heart disease should be a prime target for interventions that promote adequate screening and timely OSA diagnosis.

The epidemiology of adult obstructive sleep apnea

Obstructive sleep apnea is a chronic condition characterized by frequent episodes of upper airway collapse during sleep. Its effect on nocturnal sleep quality and ensuing daytime fatigue and sleepiness are widely acknowledged. Increasingly, obstructive sleep apnea is also being recognized as an independent risk factor for several clinical consequences, including systemic hypertension, cardiovascular disease, stroke, and abnormal glucose metabolism. Estimates of disease prevalence are in the range of 3% to 7%, with certain subgroups of the population bearing higher risk. Factors that increase vulnerability for the disorder include age, male sex, obesity, family history, menopause, craniofacial abnormalities, and certain health behaviors such as cigarette smoking and alcohol use. Despite the numerous advancements in our understanding of the pathogenesis and clinical consequences of the disorder, a majority of those affected remain undiagnosed. Simple queries of the patient or bed-partner for the symptoms and signs of the disorder, namely, loud snoring, observed apneas, and daytime sleepiness, would help identify those in need of further diagnostic evaluation. The primary objective of this article is to review some of the epidemiologic aspects of obstructive sleep apnea in adults.

Sleep duration among black and white Americans: results of the National Health Interview Survey

INTRODUCTION

Epidemiologic studies have shown the importance of habitual sleep duration as an index of health and mortality risks. However, little has been done to ascertain ethnic differences in sleep duration in a national sample. This study compares sleep duration in a sample of black and white participants in the National Health Interview Survey (NHIS).

METHOD

Data were collected from 29,818 Americans (age range 18-85 years) who participated in the 2005 NHIS. The NHIS is a cross-sectional household interview survey that uses a multistage area probability design, thus permitting representative sampling of U.S. households. During face-to-face interviews conducted by trained interviewers from the U.S. Census Bureau, respondents provided demographic data and information about physician-diagnosed chronic conditions, estimated habitual sleep duration and functional capacity, and rated their mood.

RESULTS

Fisher's exact test results indicated that blacks were less likely than whites to report sleeping 7 hours (23% vs. 30%; chi2 = 94, p < 0.0001). Blacks were more likely to experience both short sleep (< or = 5 hours) (12% vs. 8%, chi2 = 44, p < 0.0001) and long sleep (> or = 9 hours) (11% vs. 9%, chi2 = 23, p < 0.0001). Logistic regression analysis, adjusting for differences in sociodemographic factors, depression, functional capacity and medical illnesses, demonstrated that black ethnicity was a significant predictor of extreme sleep duration (Wald = 46, p < 0.0001; OR = 1.35, 95% CI: 1.24-1.47).

DISCUSSION

Independent of several sociodemographic and medical factors, blacks had more prevalent short and long sleep durations, suggesting greater variation in habitual sleep time. Therefore, blacks might be at increased risks of developing medical conditions associated with short and long sleep.

Association of ApoE genetic variants with obstructive sleep apnea in children

BACKGROUND AND PURPOSE

Although several studies have reported an association between obstructive sleep apnea (OSA) and the chromosomal region containing the Apolipoprotein E (ApoE) gene, findings about the exact location in the ApoE gene have been inconsistent. The objective of our study was thus to determine the allele, genotype, and haplotype frequencies at several single nucleotide polymorphisms (SNPs) in the region of ApoE and test their association with OSA status in children.

PATIENTS AND METHODS

Caucasian children, ranging in age from 2 to 21 years, with polysomnographic evidence of OSA (>1 obstructive apnea or obstructive hypopnea episodes per hour of sleep) were recruited in the case group. Our race- and gender-matched control group was recruited from a population-based cohort of children enrolled in the Princeton School District Study.

RESULTS

Comparison of allele and genotype frequencies between cases (n=92) and controls (n=92) revealed significant differences for SNPs rs405509 and rs7412. Multivariate logistic regression analysis with age and body mass index (BMI) as covariates revealed a significant association between OSA status and SNPs rs157580, rs405509, rs769455 and rs7412. The sliding window haplotype trend regression test revealed that SNP rs405509 was included in all haplotypes that are significantly associated with OSA status.

CONCLUSIONS

We conclude that polymorphisms involving more than one locus in the ApoE gene and its regulatory region are associated with OSA in children. Further studies replicating these findings in different populations are needed as are studies involving fine mapping of this region.

Shared genetic basis for obstructive sleep apnea and adiposity measures

INTRODUCTION

Obesity and obstructive sleep apnea each have a substantial genetic basis and commonly coexist in individuals. The degree to which the genetic underpinnings for these disorders overlap has not been previously quantified.

METHODS

A total of 1802 individuals from 310 families in the Cleveland Family Study underwent home sleep studies as well as standardized assessment of body mass index (BMI) and circumferences at the waist, hip and neck. In 713 participants with laboratory sleep studies, fasting blood samples were assayed for leptin, adiponectin and resistin. Variance component models were used to estimate heritability and genetic correlations.

RESULTS

The heritability of the apnea hypopnea index (AHI) was 0.37+/-0.04 and 0.33+/-0.07 for home and laboratory sleep studies, respectively. The genetic correlations between AHI and anthropomorphic adiposity measures ranged from 0.57 to 0.61, suggesting that obesity can explain nearly 40% of the genetic variance in sleep apnea. The magnitude of the genetic correlations between apnea severity and adipokine levels was substantially less than those with anthropomorphic measures, ranging from 0.11 to 0.46. After adjusting for BMI, no significant genetic correlation with apnea severity was observed for any of the other adiposity measures.

CONCLUSIONS

Substantial but not complete overlap in genetic bases exists between sleep apnea and anthropomorphic indices of adiposity, and this overlap accounts for more than one-third of the genetic variance in apnea severity. These findings suggest that genetic polymorphisms exist that importantly influence sleep apnea susceptibility through both obesity-dependent and -independent pathways.

Interaction between the angiotensin-converting enzyme gene insertion/deletion polymorphism and obstructive sleep apnoea as a mechanism for hypertension

OBJECTIVE

Obstructive sleep apnoea (OSA) confers a risk of hypertension and cardiovascular complications. Both the renin-angiotensin-aldosterone system and OSA are important determinants of blood pressure, but it is not fully known how they interact. The aim of this study was to explore the interaction between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and OSA in the association with hypertension.

DESIGN

A community-based, case-control design with hypertensive patients in primary care (n = 157) and normotensive population controls (n = 181).

METHODS

All subjects underwent ambulatory polysomnography during one night. OSA was defined by a minimum of 10 apnoea/hypopnoea events per hour. Office blood pressure was measured and hypertension status was assessed. The genotypes were determined using polymerase chain reaction.

RESULTS

An interaction analysis including sex, ACE I/D polymorphism (DD and ID versus II), and OSA identified a significant interaction between OSA and the ACE I/D polymorphism: odds ratio (OR) 6.3, 95% confidence interval (CI) 1.8-22.5, P = 0.004 as well as between OSA and sex: OR 3.3, 95% CI 1.1-9.6, P = 0.033. OSA was significantly associated with hypertension in men but not in women.

CONCLUSION

The interaction between the ACE gene I/D polymorphism and OSA appears to be an important mechanism in the development of hypertension, particularly in men.

Pediatric sleep apnea: implications of the epidemic of childhood overweight

Over the last 30 years, the prevalence of overweight across all pediatric age groups and ethnicities has increased substantially, with the current prevalence of overweight among adolescents estimated to be approximately 30%. Current evidence suggests that overweight is modestly associated with obstructive sleep apnea syndrome (OSAS) among young children, but strongly associated with OSAS in older children and adolescents. The rising incidence of pediatric overweight likely will impact the prevalence, presentation, and treatment of childhood OSAS. The subgroup of children who may be especially susceptible include ethnic minorities and those from households with caregivers from low socioeconomic groups. OSAS, by exposing children to recurrent intermittent hypoxemia or oxidative stress, may amplify the adverse effects of adiposity on systemic inflammation and metabolic perturbations associated with vascular disease and diabetes. When these conditions manifest early in life, they have the potential to alter physiology at critical developmental stages, or, if persistent, provide cumulative exposures that may powerfully alter long-term health profiles. An increased prevalence of overweight also may impact the response to adenotonsillectomy as a primary treatment for childhood OSAS. The high and anticipated increased prevalence of pediatric OSAS mandates assessment of optimal approaches for preventing and treating both OSAS and overweight across the pediatric age range. In this Pulmonary Perspective, the interrelationships between pediatric OSAS and overweight are reviewed, and the implications of the overweight epidemic on childhood OSAS are discussed.

Sleep in older African Americans and Caucasians at risk for sleep-disordered breathing

This study explored differences in sleep between older African Americans (AA) and Caucasians (CA) at risk for sleep-disordered breathing. Seventy AA and 70 CA were compared on ambulatory monitoring sleep variables and on self-reports on health and socioeconomic status (SES). After controlling for SES and health covariates, CA woke up significantly more often than AA (p = .018), but there were no other differences in sleep variables between the two groups. Time awake at night was related to being male, more depression, less walking, and lower income, whereas having more awakenings during the night was related to being CA, higher apnea-hypopnea index, and higher periodic leg movement index. Importance of inclusion of SES, health, and other covariates in studies exploring racial differences in sleep are discussed.