Association between sleep-disordered breathing and post-stroke fatigue in patients with ischemic stroke

OBJECTIVES

Post-stroke fatigue (PSF) is common and often disabling. Sleep-disordered breathing (SDB) is highly prevalent among stroke survivors and can cause fatigue. We explored the relationship between SDB and PSF over time.

MATERIALS AND METHODS

Ischemic stroke (IS) patients within the BASIC project were offered SDB screening with a well-validated cardiopulmonary sleep apnea test at 0, 3-, 6-, and 12-months post-stroke. The primary exposure was the respiratory event index (REI; sum of apneas plus hypopneas per hour). The primary outcome was PSF, measured by the SF-36 vitality scale. Associations between REI and PSF were evaluated using linear regression including time-by-REI interactions, allowing the effect of REI to vary over time.

RESULTS

Of the 411 IS patients who completed at least one outcome interview, 44 % were female, 61 % Mexican American (MA), 26 % non-Hispanic white, with a mean age of 64 (SD 10). Averaged across timepoints, REI was not associated with PSF. In a time-varying model, higher REI was associated with greater PSF at 3-months (β = 1.75, CI = 0.08, 3.43), but not at 6- or 12-months. Across timepoints, female sex, depressive symptoms, and comorbidity burden were associated with greater PSF, whereas MA ethnicity was associated with less PSF.

CONCLUSIONS

Higher REI was associated with modestly greater PSF in the early post-stroke period, but no association was observed at 6 months and beyond. SDB may be a modest modifiable risk factor for early PSF, but its treatment is unlikely to have a substantial impact on long-term PSF. MA ethnicity seems to be protective against PSF.

Case studies in physiology: Nocturnal cardiorespiratory adaptive differences between an Italian trekker and a Nepali guide

The cardiopulmonary system is a physiological cornerstone in the adaptive response to hypobaric hypoxia. Portable devices make it feasible nowadays to precisely assess the response to high altitude (HA) expeditions. In this study, we investigated breathing and arterial blood pressure responses during a Himalayan trek from 665 m to 4,780 m altitude in a white European (Italian) sojourner and a native Nepali (Tamang) guide, both healthy males. Resting diurnal and nocturnal data were acquired by means of ambulatory blood pressure monitoring (ABPM) and sleep apnea monitoring. We found an increase in the mean diurnal arterial blood pressure. Nocturnal blood pressure dipping was confirmed at all altitudes. Oxygen saturation decreased at altitude, with its additional nocturnal fall. Sleep apneic episodes, present in the Italian only, increased with altitude. We conclude that the nocturnal, more than diurnal, cardiorespiratory function is affected by HA hypoxia. Further studies should address the role of ethnicity, medications, and sociodemographic factors in the cardiorespiratory responses to hypobaric hypoxia.

Sleep Characteristics and Measures of Glucose Metabolism in Blacks: The Jackson Heart Study

Background Characterizing associations of sleep characteristics with blood-glucose-level factors among blacks may clarify the underlying mechanisms of impaired glucose metabolism and help identify treatment targets to prevent diabetes mellitus in blacks. Methods and Results Cross-sectional analyses were conducted in 789 blacks who completed home sleep apnea testing and 7-day wrist actigraphy in 2012-2016. Sleep-disordered breathing measurements included respiratory event index associated with 4% oxygen desaturation and minimum oxygen saturation. Sleep patterns on actigraphy included fragmented sleep indices. Associations between sleep characteristics (8 exposures) and measures of glucose metabolism (3 outcomes) were determined using multivariable linear regression. Mean (SD) age of the participants was 63 (11) years; 581 (74%) were women; 198 (25%) were diabetes mellitus, and 158 (20%) were taking antihyperglycemic medication. After multivariable adjustment, including antihyperglycemic medication use, the betas (95% CI) for fasting glucose and hemoglobin A1c, respectively, for each SD higher level were 0.13 (0.02, 0.24) mmol/L and 1.11 (0.42, 1.79) mmol/mol for respiratory event index associated with 4% oxygen desaturation and 0.16 (0.05, 0.27) mmol/L and 0.77 (0.10, 1.43) mmol/mol for fragmented sleep indices. Among 589 participants without diabetes mellitus, the betas (95% CI) for homeostatic model assessment of insulin resistance for each SD higher level were 1.09 (1.03, 1.16) for respiratory event index associated with 4% oxygen desaturation, 0.90 (0.85, 0.96) for minimum oxygen saturation, and 1.07 (1.01, 1.13) for fragmented sleep indices. Conclusions Sleep-disordered breathing, overnight hypoxemia, and sleep fragmentation were associated with higher blood glucose levels among blacks.

Association Between Sleep Disordered Breathing and Left Ventricular Function: A Cross-Sectional Analysis of the ECHO-SOL Ancillary Study

BACKGROUND

Prior studies have found that sleep-disordered breathing (SDB) is common among those with left ventricular (LV) dysfunction and heart failure. Few epidemiological studies have examined this association, especially in US Hispanic/Latinos, who may be at elevated risk of SDB and heart failure.

METHODS

We examined associations between SDB and LV diastolic and systolic function using data from 1506 adults aged 18 to 64 years in the Hispanic Community Health Study/Study of Latinos ECHO-SOL Ancillary Study (2011-2014). Home sleep testing was used to measure the apnea-hypopnea index, a measure of SDB severity. Echocardiography was performed a median of 2.1 years later to quantify LV diastolic function, systolic function, and structure. Multivariable linear regression was used to model the association between apnea-hypopnea index and echocardiographic measures while accounting for the complex survey design, demographics, body mass, and time between sleep and echocardiographic measurements.

RESULTS

Each 10-unit increase in apnea-hypopnea index was associated with 0.2 (95% CI, 0.1-0.3) lower E', 0.3 (0.1-0.5) greater E/E' ratio, and 1.07-fold (1.03-1.11) higher prevalence of diastolic dysfunction as well as 1.3 (0.3-2.4) g/m2 greater LV mass index. These associations persisted after adjustment for hypertension and diabetes mellitus. In contrast, no association was identified between SDB severity and subclinical markers of LV systolic function.

CONCLUSIONS

Greater SDB severity was associated with LV hypertrophy and subclinical markers of LV diastolic dysfunction. These findings suggest SDB in Hispanic/Latino men and women may contribute to the burden of heart failure in this population.

Associations between ankle-brachial index, diabetes, and sleep apnea in the Hispanic community health study/study of Latinos (HCHS/SOL) database

BACKGROUND

Sleep apnea and diabetes mellitus (DM) negatively impact cardiovascular health. One important indicator of cardiovascular health is the Ankle-Brachial Index (ABI). Either low ABI or high ABI are signs of peripheral vascular impairment. Impaired vascular health and DM, together, might provoke sleep apnea; however, information regarding these relationships is limited. Therefore, this study aimed to investigate the association between ABI, DM status, and severity of obstructive sleep apnea in people of Hispanic/Latino descent who are diverse in culture, environmental exposures, nativity, socioeconomic status, and disease burden.

METHODS

A cross sectional analysis from a multi-center epidemiologic study, Hispanic Community Health Study/Study of Latinos, was utilized and included 3779 participants (mean age 55.32 ± 7.67, females 57.9%). The sample was divided into 4 groups based on the American Diabetes Association diagnostic guidelines (no DM or DM), and the ABI status (normal and abnormal). Multiple linear regression analysis was used to determine the association of the four groups and other independent variables with severity of sleep apnea measured by apnea-hypopnea index. Kruskal-Wallis H test was used for comparisons between groups for the apnea-hypopnea index. The significant level was set at 0.01.

RESULTS

There were significant differences between groups in the mean of apnea-hypopnea index (P < 0.001; no DM + normal ABI = 5.42 ± 9.66, no DM + abnormal ABI = 7.11 ± 11.63, DM + normal ABI = 10.99 ± 15.16, DM + abnormal ABI = 12.81 ± 17.80). Linear regression showed that DM and abnormal ABI were significantly associated with severe sleep apnea (β = 3.25, P = 0.001) after controlling for age, sex, BMI, income, education, alcohol use, cigarette use, hypertension or related medication, stroke and statin use.

CONCLUSION

These findings suggest that people with DM and abnormal ABI were more likely to have high apnea-hypopnea index compared to the other groups. We observed gradual increasing in the severity of sleep apnea from low abnormality groups to high abnormality groups for Hispanic/Latino. Further work should elucidate the association of DM, abnormal ABI and sleep apnea with longer term outcomes, and replicate this work in different populations.

Association Between Sleep Apnea and Blood Pressure Control Among Blacks

BACKGROUND

Blacks have a high prevalence of hypertension and uncontrolled blood pressure (BP), each of which may be partially explained by untreated sleep apnea. We investigated the association of sleep apnea with uncontrolled BP and resistant hypertension in blacks.

METHODS

Between 2012 and 2016, Jackson Heart Sleep Study participants (N=913) underwent an in-home Type 3 sleep apnea study, clinic BP measurements, and anthropometry. Moderate or severe obstructive sleep apnea (OSA) was defined as a respiratory event index ≥15, and nocturnal hypoxemia was quantified as percent sleep time with <90% oxyhemoglobin saturation. Prevalent hypertension was defined as either a systolic BP ≥130 mm Hg or diastolic BP >80mm Hg, use of antihypertensive medication, or self-report of a diagnosis of hypertension. Controlled BP was defined as systolic BP <130 mm Hg and diastolic BP <80 mm Hg; uncontrolled BP as systolic BP ≥130 mm Hg or diastolic BP ≥80 mm Hg with use of 1 to 2 classes of antihypertensive medication; and resistant BP as systolic BP ≥130 mm Hg or diastolic BP ≥80 mm Hg with the use of ≥3 classes of antihypertensive medication (including a diuretic) or use of ≥4 classes of antihypertensive medication regardless of BP level. Multinomial logistic regression models were fit to determine the association between OSA severity and uncontrolled BP or resistant hypertension (versus controlled BP) after multivariable adjustment.

RESULTS

The analytic sample with hypertension (N=664) had a mean age of 64.0 (SD,10.6) years, and were predominately female (69.1%), obese (58.6%), and college educated (51.3%). Among the sample, 25.7% had OSA, which was untreated in 94% of participants. Overall, 48% of participants had uncontrolled hypertension and 14% had resistant hypertension. After adjustment for confounders, participants with moderate or severe OSA had a 2.0 times higher odds of resistant hypertension (95% confidence interval [CI], 1.14-3.67). Each standard deviation higher than <90% oxyhemoglobin saturation was associated with an adjusted odds ratio for resistant hypertension of 1.25 (95% CI 1.01-1.55). OSA and <90% oxyhemoglobin saturation were not associated with uncontrolled BP.

CONCLUSION

Untreated moderate or severe OSA is associated with increased odds of resistant hypertension. These results suggest that untreated OSA may contribute to inadequate BP control in blacks.

[Chinese expert consensus on the assessment and management of stroke-related sleep disorders]

Stroke-related sleep disorders (SSD) are common symptoms after stroke, which are common but easily ignored. Studies have shown that sleep disorders in stroke patients would have negative impact on prognosis. However, there is still a lack of consensus and guidance on SSD evaluation and management worldwide. This consensus proposes the concept of SSD based on systemic literature review and discussion with experts. It comprises recommendations of assessment and management for all types of SSD, including insomnia, excessive daytime sleepiness, sleep apnea, rapid eye movement (REM) sleep behavior disorder, restless leg syndrome/periodic limb movements of sleep, circadian rhythm sleep-wake disorders. The purpose of this consensus is to provide a standard reference of SSD management.

Sleep Patterns and Hypertension Using Actigraphy in the Hispanic Community Health Study/Study of Latinos

BACKGROUND

The aim of this study was to evaluate the association between actigraphy-based measures of sleep and prevalent hypertension in a sample of US Latinos.

METHODS

We analyzed data from 2,148 participants of the Sueño Sleep Ancillary Study of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), who underwent 1 week of wrist actigraphy to characterize sleep duration, sleep efficiency, sleep fragmentation index, and daytime naps. Insomnia was defined as an Insomnia Severity Index ≥ 15. Hypertension was defined based on self-reported physician diagnosis. Survey linear regression was used to evaluate the association of sleep measures with hypertension prevalence. Sensitivity analyses excluded participants with an apnea-hypopnea index (AHI) ≥ 15 events/h.

RESULTS

The mean age was 46.3 ± 11.6 years, and 65% of the sample consisted of women. The mean sleep duration was 6.7 ± 1.1 hours. Thirty-two percent of the sample had hypertension. After adjusting for age, sex, ethnic background, site, and AHI, each 10% reduction in sleep efficiency was associated with a 7.5% (95% CI, -12.9 to -2.2; P = .0061) greater hypertension prevalence, each 10% increase in sleep fragmentation index was associated with a 5.2% (95% CI, 1.4-8.9; P = .0071) greater hypertension prevalence, and frequent napping was associated with a 11.6% greater hypertension prevalence (95% CI, 5.5-17.7; P = .0002). In contrast, actigraphy-defined sleep duration (P = .20) and insomnia (P = .17) were not associated with hypertension. These findings persisted after excluding participants with an AHI ≥ 15 events/h.

CONCLUSIONS

Independent of sleep-disordered breathing, we observed associations between reduced sleep continuity and daytime napping, but not short sleep duration, and prevalent hypertension.

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 the associations between obesity measures and severity of sleep-disordered breathing: the Multi-Ethnic Study of Atherosclerosis

OBJECTIVES

The objective of this study was to evaluate associations between obesity measures and sleep-disordered breathing severity among White, Black, Hispanic, and Chinese Americans.

METHODS

The method used in this study was a community-based cross-sectional study of 2053 racially/ethnically diverse adults in the Multi-Ethnic Study of Atherosclerosis. Anthropometry and polysomnography were used to measure obesity and apnea-hypopnea index (AHI). Linear regression models were fitted to investigate associations of body mass index (BMI) and waist circumference with AHI (log transformed) with adjustment for sociodemographics, lifestyle factors, and comorbidities.

RESULTS

The mean participant age was 68.4 (range: 54-93) years; 53.6% of participants were women. The median AHI was 9.1 events/h. There were significant associations of BMI and waist circumference with AHI in the overall cohort and within each racial/ethnic group. A significant interaction was observed between race/ethnicity and BMI (P_interaction = 0.017). Models predicted that for each unit increase in BMI (kg/m²), the mean AHI increased by 19.7% for Chinese, 11.6% for Whites and Blacks, and 10.5% for Hispanics. Similarly, incremental changes in waist circumference were associated with larger increases in AHI among Chinese than among other groups.

CONCLUSIONS

Associations of BMI and waist circumference with AHI were stronger among Chinese than among other racial/ethnic groups. These findings highlight a potential emergence of elevated sleep-disordered breathing prevalence occurring in association with increasing obesity in Asian populations.

Sleep apnea is independently associated with peripheral arterial disease in the Hispanic Community Health Study/Study of Latinos

OBJECTIVE

Sleep apnea (SA) has been linked with various forms of cardiovascular disease, but little is known about its association with peripheral artery disease (PAD) measured using the ankle-brachial index. This relationship was evaluated in the Hispanic Community Health Study/Study of Latinos.

APPROACH AND RESULTS

We studied 8367 Hispanic Community Health Study/Study of Latinos participants who were 45 to 74 years of age. Sleep symptoms were examined with the self-reported Sleep Health Questionnaire. SA was assessed using an in-home sleep study. Systolic blood pressure was measured in all extremities to compute the ankle-brachial index. PAD was defined as ankle-brachial index <0.90 in either leg. Multivariable logistic regression was used to investigate the association between moderate-to-severe SA, defined as apnea-hypopnea index ≥15, and the presence of PAD. Analyses were adjusted for covariates. The prevalence of PAD was 4.7% (n=390). The mean apnea-hypopnea index was significantly higher among adults with PAD compared with those without (11.1 versus 8.6 events/h; P=0.046). After adjusting for covariates, moderate-to-severe SA was associated with a 70% increase in the odds of PAD (odds ratio, 1.7; 95% confidence interval, 1.1-2.5; P=0.0152). This association was not modified by sex (P=0.8739). However, there was evidence that the association between moderate-to-severe SA and PAD varied by Hispanic/Latino background (P<0.01). Specifically, the odds were stronger in Mexican (adjusted odds ratio, 2.9; 95% confidence interval, 1.3-6.2) and in Puerto Rican Americans (adjusted odds ratio, 2.0; 95% confidence interval, 0.97-4.2) than in other backgrounds.

CONCLUSIONS

Moderate-to-severe SA is associated with higher odds of PAD in Hispanic/Latino adults.

Characteristics of sleep-disordered breathing in Japanese patients with acromegaly

Sleep-disordered breathing (SDB), especially sleep apnea-hypopnea syndrome (SAS), is often observed in patients with active acromegaly. This complication is a risk factor for cardiovascular disease and associated with increased morbidity and mortality in acromegaly. However there is little information on SDB in Japanese patients with acromegaly. We investigated the prevalence of SDB and association between the severity of SDB and various features and biomarkers in Japanese patients with acromegaly. Twenty-four Japanese patients with active acromegaly underwent overnight cardiorespiratory monitoring, hormonal assays and cephalometric measurements on X-ray. A high prevalence of SDB was detected in acromegaly (87.5%). Log apnea-hypopnea index (AHI) correlated positively with soft palate length / body height (X-ray) (r=0.44, p=0.043), but not with log growth hormone levels and insulin-like growth factor type-1 standard deviation scores, size of pituitary adenoma, disease duration, body mass index, waist circumference, estimated visceral fat area, heel pad thickness / height, tongue thickness/ height, or oropharyngeal dimension/ height. In conclusion, our study demonstrated a high prevalence of SDB in Japanese patients with acromegaly, and its severity correlated with soft palate length. Based on the high incidence of SDB identified in the present study, we recommend that all patients with acromegaly are routinely screened for SDB for early diagnosis and treatment.

Association between sleep apnea, snoring, incident cardiovascular events and all-cause mortality in an adult population: MESA

BACKGROUND

We assessed the association between sleep apnea, snoring, incident cardiovascular (CV) events and all-cause mortality in the Multi Ethnic Study of Atherosclerosis (MESA) cohort.

METHODS

Out of 5338 respondents to a sleep questionnaire administered during the second MESA exam period, 208 had physician diagnosed sleep apnea (PDSA), 1452 were habitual snorers (HS) and 3678 were neither a habitual snorer nor had PDSA (normal participants). Cox proportional hazard analysis was used to assess the associations adjusting for age, gender, race/ethnicity, smoking, diabetes mellitus, total cholesterol, HDL, triglycerides, BMI, current alcohol use, benzodiazepine use, BP medications and statin use.

RESULTS

Over a 7.5 year average follow-up period, 310 adjudicated CV events including MI, stroke, angina, resuscitated cardiac arrest, stroke death and CVD death and 189 deaths occurred. Compared to HS, PDSA was associated with higher incident CV rates in both univariate and multivariable models [hazard ratio (95%); 1.89 (1.22-2.93), p = 0.004 and 1.91 (1.20-3.04), p = 0.007, respectively]. PDSA was also associated with a higher death rates compared with HS [hazard ratio (95%); 2.13 (1.25-3.63), p = 0.006 and 2.70 (1.52-4.79), p = 0.007, respectively]. Compared with normal participants, PDSA had higher incident CV event rates in both univariate and multivariable models [hazard ratio (95%); 2.23 [1.39-3.60], p = 0.001 and 2.16 [1.30-3.58], p = 0.003, respectively]. Similarly, PDSA had a higher death rate compared with normal participants in both the univariate and multivariable models [hazard ratio (95% CI); 2.44 (1.36-4.37), p = 0.003 and 2.71 (1.45-5.08), p =0 .002, respectively]. Habitual snorers had similar incident CV event rates and death rates in both univariate and multivariable models compared with normal participants.

CONCLUSION

PDSA but not habitual snoring was associated with high incident CV events and all-cause mortality in a multi-ethnic population based study of adults free of clinical CV disease at baseline.

Ethnic disparities in CPAP adherence in New Zealand: effects of socioeconomic status, health literacy and self-efficacy

STUDY OBJECTIVES

We aimed to investigate the influence of ethnicity on adherence with continuous positive airway pressure (CPAP) in a sample of New Zealand patients.

DESIGN

Observational study over one month.

SETTING

A university-based sleep laboratory.

PATIENTS

126 consecutively consenting CPAP-naïve patients (19.8% Māori, mean±SD apnea-hypopnea index 57.9 ± 38.9 events/h, CPAP 11.1 ± 3.1 cm H2O).

INTERVENTIONS

Patients underwent a 4-week supervised home trial of CPAP following pressure titration.

MEASUREMENTS AND RESULTS

Self-identified ethnicity (Māori/non-Māori), Epworth Sleepiness Scale, Self-Efficacy Measure for Sleep Apnea, Rapid Estimate of Adult Literacy in Medicine, New Zealand Deprivation Index (calculated from residential address), New Zealand Individual Deprivation Index (validated 8-item questionnaire), educational history, income, and employment assessed at baseline were compared to objective CPAP adherence after one month. Māori demonstrated significantly lower usage than non-Māori (median 5.11, interquartile range 2.24 h/night compared with median 5.71, interquartile range 2.61 h/night, P = 0.05). There were no significant relationships between adherence and subjective sleepiness, health literacy, or self-efficacy. In a multivariate logistic regression model incorporating 5 variables (ethnicity, eligibility for government-subsidized healthcare, individual deprivation scores, income, and education), non-completion of tertiary education, and high individual socioeconomic deprivation remained significant independent predictors of average CPAP adherence not reaching ≥ 4 h (odds ratio 0.25, 95% CI 0.08-0.83, P = 0.02; odds ratio 0.10, 95% CI 0.02-0.86, P = 0.04, respectively). The overall model explained approximately 23% of the variance in adherence.

CONCLUSIONS

The disparity in CPAP adherence demonstrated between Māori and non-Māori can be explained in part by lower education levels and socioeconomic status.

Longitudinal association between short sleep, body weight, and emotional and learning problems in Hispanic and Caucasian children

STUDY OBJECTIVE

To determine the impact of lower amounts of childhood sleep assessed by polysomnogram on development of obesity, being anxious or depressed, or having learning problems 5 years later.

DESIGN

Prospective cohort.

PARTICIPANTS

Subjects were 304 community participants from the Tucson Children's Assessment of Sleep Apnea study, aged 6-12 years old at baseline.

MEASUREMENTS AND RESULTS

Children were classified according to baseline sleep as those who slept ≥ 9 h/night, those who slept > 7.5 to < 9 h/night, and those who slept ≤ 7.5 h/night. Odds of overweight/obese (≥ 85(th) BMI percentile), obese (≥ 95(th) BMI percentile), anxious or depressed, and learning problems at follow-up were assessed according to baseline sleep categories. Children who slept ≤ 7.5 h/night had higher odds of being obese (OR = 3.3, P < 0.05) at follow-up than children who slept ≥ 9 h/night. Borderline significance for overweight/obese (OR = 2.2, P < 0.1), anxious or depressed (OR = 3.3, P < 0.1), and having learning problems (OR = 11.1, P < 0.1) were seen for children who slept ≤ 7.5 h/night as compared to those who slept ≥ 9 h/night. A mean increase in BMI of 1.7 kg/m(2) (P = 0.01) over the 5 years of follow-up was seen for children who slept ≤ 7.5 h/night compared to those who slept ≥ 9 h/night. These relationships did not differ between Hispanic and Caucasian children.

CONCLUSIONS

Children with reduced amounts of sleep (≤ 7.5 h/night) had an increased risk for higher body weight in early adolescence. Similarly, children who slept ≤ 7.5 h/night had higher risk of being anxious or depressed or having learning problems in early adolescence.

Racial/ethnic differences in the prevalence of snoring and sleep disordered breathing in young children

STUDY OBJECTIVE

To determine whether there are racial/ethnic differences in the prevalence of pediatric snoring and sleep disordered breathing (SDB).

METHODS

In this cross-sectional study, parents or caretakers of 346 children, aged 2 through 6 years, attending well-child care visits at 5 general pediatric offices and clinics (3 academic, 2 private) in Brooklyn, NY completed the Sleep-Related Breathing Disorders Scale of the Pediatric Sleep Questionnaire (PSQ) along with a survey on demographics, prior treatment for SDB, and parental knowledge of pediatric SDB. The child's height and weight were recorded from the office visit.

RESULTS

The prevalence of snoring was 13.9% (95% CI 10.2, 17.5) and of SDB was 9.4% (95% CI 6.3, 12.6). The odds of snoring for black children was 2.5 as great as for white children, and for Hispanic children was 2.3 as great as for white children (p = 0.031). There was a higher, non-statistically significant prevalence of abnormal PSQ scores in black and Hispanic children than white children. On multivariate analysis, only black race (OR 3.1 95% CI 1.1, 8.9) and prematurity (OR 4.4 95% CI 1.6, 12.4) were associated with snoring; male gender (OR 2.9 95% CI 1.1, 8.5) was associated with SDB. Knowledge regarding SDB was low among parents and caretakers. The degree of knowledge present was not associated with parental concern about snoring and discussion of the snoring with the child's pediatrician.

CONCLUSIONS

Black race and prematurity are independent predictors of snoring. The degree of parental knowledge regarding SDB was not associated with seeking medical treatment.

Obstructive sleep apnoea among professional taxi drivers: a pilot study

PURPOSE

This study aimed to describe the distribution of risk factors for obstructive sleep apnoea syndrome (OSAS) among taxi drivers, and to investigate differences by ethnicity in OSAS symptoms among drivers.

METHODS

A two-page postal questionnaire was completed by 241 professional taxi drivers from Wellington, New Zealand. Obstructive sleep apnoea syndrome was defined as having an estimated 15 or more respiratory disturbances, per hour of sleep (Respiratory Disturbance Index (RDI)> or =15) and self-reported daytime sleepiness.

RESULTS

Pacific and Māori taxi drivers were more likely to have symptoms and risk factors for OSAS, compared to non-Māori non-Pacific drivers. In particular, Pacific drivers had a significantly increased pre-test probability of having moderate-severe OSA (RDI> or =15).

CONCLUSIONS

Some professional taxi drivers are at increased risk for moderate-severe OSAS, especially Pacific and Māori taxi drivers. Untreated OSAS increases motor vehicle crash risk, so these findings have implications for the health and safety of drivers and their passengers. They suggest a need for more comprehensive research to guide policy on medical examinations required for licensing professional drivers as fit to drive.

Craniofacial abnormalities in Chinese patients with obstructive and positional sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent episodes of a complete or partial collapse of the upper airway during sleep. Traditionally, the disease is diagnosed by overnight polysomnography. Studies have shown correlation between parameters of cephalometry and severity of sleep apnea. We wish to determine the variable of craniofacial dimensions in the upper airway that contribute to OSA, and to investigate the significance of craniofacial measurements in positional and non-positional sleep apnea patients.

METHODS

From July 2002 to June 2006, we studied 84 males and 15 females who came to the sleep center because of daytime sleepiness. All the participants underwent overnight polysomnography and lateral cephalograms, performed by an experienced technician.

RESULTS

Craniofacial measurements of gnathion-gonion, anterior superior hyoid to mandibular plane (MP-H), posterior nasal spine (PNS) to the velum tip (SPL), widest point of the soft palate (SPW), and the product of PNS to the velum tip and widest point of the soft palate (product of soft palate (SPP)=SPL x SPW) were positively related to the apnea/hypopnea index (AHI). The velum tip to the pharyngeal wall parallel to the Frankfurt horizontal (PAS) was negatively related to the AHI. We further divided the study subjects into 4 groups according to AHI value (group 1, AHI<5; group 2, 5 <or= AHI<15; group 3, 15 <or= AHI<30; group 4, AHI >or=30). Age, body mass index (BMI), neck circumference (NC), distances of PAS, SPL, SPW, SPP and angle of sella-nasion-infradentale (SNB) were significantly different depending on the degree of severity of sleep-disordered breathing (SDB). Patients who were older, with a high BMI and longer MP-H distance, had more daytime sleepiness (Epworth sleepiness scale, ESS). Furthermore, lower AHI values and longer PAS measurements were found in the positional sleep apnea group when compared to the non-positional sleep apnea group. After adjusting for confounding factors of age, BMI and NC, we found that BMI, MP-H distance and PAS measurement were correlated with severity of OSA.

CONCLUSIONS

Cephalometry could be a useful and inexpensive clinical tool to evaluate Chinese patients with OSA. MP-H and PAS should be measured in Chinese patients with OSA. MP-H was correlated with ESS. The PAS measurement was narrower in non-positional OSA patients compared to positional OSA patients.

Ethnic difference in periodic limb movements in children

BACKGROUND

Epidemiological studies have suggested that ethnicity is a risk factor for sleep-disordered breathing (SDB) and that African-American children are three times more likely than Caucasian children to have SDB. Ethnic differences in sleep architecture and other routinely assessed sleep parameters have not been critically assessed, thus the aim of this study was to compare sleep characteristics in African-American and Caucasian children.

METHODS

A total of 41,363 sleep questionnaires were mailed to parents of children aged 5-7 years in Jefferson County, KY. Parents of snoring and non-snoring children were invited to have their child undergo overnight polysomnography.

RESULTS

Complete questionnaires were returned by 9872 families (23% response rate). Of these, 689 agreed to undergo polysomnography, and 542 complete polysomnograms were obtained (5.7% of questionnaire respondents). There were 391 Caucasian and 151 African-American children with a mean age of 6.7+/-0.5 years who underwent overnight polysomnographic evaluation. No differences between groups were observed for sleep latency, total sleep time, sleep efficiency, or rapid eye movement (REM) latency. African-American children had slightly increased stage 3 sleep (6.0+/-2.8% vs. 5.4+/-2.8%; p=0.01), although the total proportion of slow wave sleep was similar. Higher respiratory arousal index (3.6+/-6.5/h vs. 1.4+/-2.7/h; p<0.001) and total arousal index (11.5+/-5.2/h vs. 9.8+/-4.8/h; p<0.001) emerged in African-American children, who were more likely to have mild SDB (AHI>1:34% in African-American vs. 24% in Caucasian; p=0.017) and SDB (AHI>5: 22.5% vs. 7%; p<0.001). However, Caucasian children were more likely to have periodic leg movements during sleep (PLMS; 16.5% vs. 7% in AA; p=0.004). The odds ratio for a Caucasian child to have PLMS was 2.6 (95% confidence interval (CI) 1.3-5.3; p=0.006). Furthermore, in the absence of SDB, the odds ratio for a Caucasian child to have PLMS was 9.5 (95% CI: 2.2-39.9; p=0.002).

CONCLUSIONS

African-American and Caucasian children have similar sleep architecture. African-American children are more likely to display respiratory disturbances during sleep, while PLMS are significantly more prevalent among Caucasian children.

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.

Comparing night-to-night variability of sleep measures in elderly African Americans and Whites

There has been great interest in the night-to-night variability of sleep-disordered breathing because of the implications for the accuracy and costs associated with diagnostic testing. Night-to-night variability of sleep and respiratory parameters were examined in 66 older Whites and 56 older African Americans. Each participant had his or her sleep recorded for 2 nights with portable recording equipment. The correlations between the 2 nights were all large. Analyses of variance showed that men had a greater change in apnea index and in number of apneas than women. There were no differences in the parameters for African Americans versus Whites. One night of sleep recording may be sufficient for studying sleep disorders in elderly persons.

Racial differences in clinical presentation of patients with sleep-disordered breathing

We characterized differences in severity, presentation, and treatment compliance in sleep-disordered breathing (SDB) between African Americans (AA) and Caucasians (W). We retrospectively analyzed demographics, proxy measures of socioeconomic position, concurrent illness, presenting complaints, polysomnographic data including respiratory disturbance index (RDI) and time less than 90% O2 saturation (T90), and acceptance of and long-term compliance with CPAP therapy. Over 1 year there were 128 AA, 102 W, and 3 "other." AA were younger (44.9+/-14.1 vs. 49.2+/-14.5 years; P=0.022), had greater body mass index (BMI) (39.7+/-10.7 vs. 33.4+/-9.2 kg/m2; p<0.0001), and reported lower estimated median household income (MHI) than W ($33,365+/-15,236 vs. $52,641+/-20,209; p<0.0001). OSA was more severe among AA: (median RDI: AA 32.9, W 29.1 events/h; p=0.008; median T90: AA 17.6 vs. W 5.3 per minute; P=0.006). However, after adjustment for BMI and MHI, differences between AA and W in RDI were not significant. Equal frequencies of AA and W accepted and were compliant with CPAP. We conclude that while AA present with more severe OSA than W this was accounted for by factors known to influence OSA severity. Further, there were no racial differences in accepting and adhering to therapy with CPAP.

Sleep-disordered breathing and hypertension among African Americans

This study investigated differences in sleep-disordered breathing (SDB) between hypertensives without a family history of hypertension and hypertensives with a family history. Furthermore, it examined whether these two groups differed in the severity of SDB. Patients were African Americans (n=162, mean age=51.19+/-13.77 years; mean body mass index (BMI)=37.85+/-9.51 kg/m2, male=57%), who were referred to the clinic because of a sleep complaint. Sleep was recorded in the laboratory using standard physiological parameters; all parameters were analysed by a trained scorer. Altogether, 91% of the patients received an SDB diagnosis. Of these patients, 25% were hypertensives without a family history, 20% were hypertensives with a family history, and 55% were normotensives. We found a significant difference between these patient groups regarding the severity of SDB (F14,158=1.823, P<0.05), but no significant group difference was observed in the rate of SDB. Increasing weight was accompanied by increasing severity of SDB. The finding that hypertensive patients with or without a positive family history showed worse oxygenation and respiratory characteristics than did normotensives is consistent with previous research. Of note, hypertensives reporting a family history were characterized by a greater number of oxygen desaturations and apnoea hypopnoea index than those typified only by a current diagnosis of hypertension. Hypertensives with a family history are likely to show a profile of greater blood pressure, higher BMI, and more severe SDB, which by all accounts are more common among African Americans.

Linkage of serum leptin levels in families with sleep apnea

OBJECTIVE

To identify regions on the genome linked to plasma leptin levels.

DESIGN

Full genome scan with 402 microsatellite markers, spaced approximately 10 cM apart. Data were analyzed using the Haseman-Elston regression linkage analysis.

SUBJECTS

A total of 160 sibling pairs from 59 predominantly African American, obese families recruited to participate in a genetic-epidemiological study of obstructive sleep apnea.

MEASUREMENTS

Serum leptin levels adjusted for age, sex, race and body mass index (BMI).

RESULTS

Suggestive linkage peaks were observed on chromosomes 2 (P=0.00170; marker D2S1384), 3 (P=0.00007; marker D3S3034), 4 (P=0.00020; marker D4S1652) and 21 (P=0.00053; marker D21s1411).

CONCLUSION

The peak on chromosome 3 is near the gene for glycogensynthase kinase 2 beta, an important factor in glucose homeostasis. Linkage was generally stronger after BMI adjustment, suggesting the potential influence of a number of metabolic pathways on leptin levels other than those that directly determine obesity levels. The evidence of linkage for leptin levels is consistent with prior linkage analyses for cholesterol, hypertension and other metabolic phenotypes.

Risk factors associated with habitual snoring and sleep-disordered breathing in a multi-ethnic Asian population: a population-based study

INTRODUCTION

There is scant data on the risk factors of sleep-disordered breathing (SDB) in the general population in Asian countries.

METHODS

Cross-sectional survey of a random population sample of 2298 adults aged 20-75 years, stratified by gender, ethnicity (Chinese, Malay and Indian) and age. An interviewer-administered questionnaire was used to elicit responses to questions on daytime somnolence and nocturnal events. Three categories of SDB were defined for analysis: habitual snoring; apnoeic snoring (SDB I); and apnoeic snoring or snoring with diurnal hypersomnia (SDB II).

RESULTS

Snoring was reported by 201 persons (6.8%), SDB-I in 44 (1.9%) and SDB-II in 112 (4.9%) in the sample. The adjusted odds ratio (95% C.I.) of association with snoring were: male gender, 3.79 (2.69-5.33); older age (>60 years old), 2.15 (1.41-3.29); Indian versus Chinese, 1.54 (1.05-2.25); family history, 2.21 (1.56-3.12); obesity (BMI>30), 2.64 (1.62-4.30); neck circumference (>40 cm), 2.57 (1.59-4.11); and cigarette smoking, 2.05 (1.21-3.45). The risk factors for SDB were similar to that of snoring.

CONCLUSION

Population risk factors associated with habitual snoring and SDB in Singapore are largely similar to those reported in other populations. Differential risks underscore the importance of ethnicity in determining the burden of SDB.

Cognitive changes and sleep disordered breathing in elderly: differences in race

OBJECTIVES

Sleep disordered breathing (SDB) is a highly prevalent sleep disorder in older persons. It is known to be associated with reductions in cognitive function. As part of a larger study examining SDB in African-Americans and Caucasians, it became possible to examine whether racial background may differentially affect the relationship between SDB and cognitive performance.

METHODS

Community-dwelling African-American and Caucasian elderly (ages 65+) at high risk for SDB were tested at two time points. During each visit, subjects were interviewed in their homes about their sleep and medical condition. The Mini-Mental Status Examination (MMSE) was used to assess cognitive function. Objective sleep studies were recorded in the subjects' homes and scored for sleep, apneic events, and oxygen saturation levels.

RESULTS

Increases in respiratory disturbance index (RDI) were associated with decreases in cognitive performance over time, after controlling for gender and education level. There were no differential effects of race on this relationship. There was no relationship between declining cognitive function and hypoxemia.

CONCLUSIONS

Analyses of the data confirm that declining cognitive function in older persons with mild to moderate SDB is related to the amount of respiratory disturbances occurring at night, and suggest that the effect of SDB on cognitive decline is unrelated to race and measured hypoxemia. The large number of community-dwelling elderly with mild to moderate SDB may accrue considerable benefits (both cognitively and medically) from the treatment of SDB, even if they are not markedly hypoxemic.

Parasomnias and sleep disordered breathing in Caucasian and Hispanic children - the Tucson children's assessment of sleep apnea study

BACKGROUND

Recent studies in children have demonstrated that frequent occurrence of parasomnias is related to increased sleep disruption, mental disorders, physical harm, sleep disordered breathing, and parental duress. Although there have been several cross-sectional and clinical studies of parasomnias in children, there have been no large, population-based studies using full polysomnography to examine the association between parasomnias and sleep disordered breathing. The Tucson Children's Assessment of Sleep Apnea study is a community-based cohort study designed to investigate the prevalence and correlates of objectively measured sleep disordered breathing (SDB) in pre-adolescent children six to 11 years of age. This paper characterizes the relationships between parasomnias and SDB with its associated symptoms in these children.

METHODS

Parents completed questionnaires pertaining to their child's sleep habits. Children had various physiological measurements completed and then were connected to the Compumedics PS-2 sleep recording system for full, unattended polysomnography in the home. A total of 480 unattended home polysomnograms were completed on a sample that was 50% female, 42.3% Hispanic, and 52.9% between the ages of six and eight years.

RESULTS

Children with a Respiratory Disturbance Index of one or greater were more likely to have sleep walking (7.0% versus 2.5%, p < 0.02), sleep talking (18.3% versus 9.0%, p < 0.006), and enuresis (11.3% versus 6.3%, p < 0.08) than children with an Respiratory Disturbance Index of less than one. A higher prevalence of other sleep disturbances as well as learning problems was observed in children with parasomnia. Those with parasomnias associated with arousal were observed to have increased number of stage shifts. Small alterations in sleep architecture were found in those with enuresis.

CONCLUSIONS

In this population-based cohort study, pre-adolescent school-aged children with SDB experienced more parasomnias than those without SDB. Parasomnias were associated with a higher prevalence of other sleep disturbances and learning problems. Clinical evaluation of children with parasomnias should include consideration of SDB.

Ethnicity, sleep, mood, and illumination in postmenopausal women

BACKGROUND

This study examined how ethnic differences in sleep and depression were related to environmental illumination and circadian rhythms.

METHODS

In an ancillary study to the Women's Health Initiative, 459 postmenopausal women were recorded for one week in their homes, using wrist monitors. Sleep and illumination experience were estimated. Depression was self-rated with a brief adjective check list. Affective diagnoses were made using the SCID interview. Sleep disordered breathing was monitored with home pulse oximetry.

RESULTS

Hispanic and African-American women slept less than European-American women, according to both objective recordings and their own sleep logs. Non-European-American women had more blood oxygen desaturations during sleep, which accounted for 26% of sleep duration variance associated with ethnicity. Hispanic women were much more depressed. Hispanic, African-American and Native-American women experienced less daily illumination. Less daily illumination experience was associated with poorer global functioning, longer but more disturbed sleep, and more depression.

CONCLUSIONS

Curtailed sleep and poor mood were related to ethnicity. Sleep disordered breathing was a factor in the curtailed sleep of minority women. Less illumination was experienced by non-European-American women, but illumination accounted for little of the contrasts between ethnic groups in sleep and mood. Social factors may be involved.

Sleep architecture in normal Caucasian and Hispanic children aged 6-11 years recorded during unattended home polysomnography: experience from the Tucson Children's Assessment of Sleep Apnea Study (TuCASA)

OBJECTIVE

To obtain normative sleep architecture data from unattended home polysomnography in Caucasian and Hispanic children aged 6-11 years.

DESIGN AND SUBJECTS

Unattended home polysomnography was performed on a single night in Caucasian and Hispanic children aged 6-11 years as part of the Tucson Children's Assessment of Sleep Apnea Study (TuCASA), a cohort study designed to examine the prevalence and correlates of sleep disordered breathing. A subset of 42 children enrolled in TuCASA who had no symptoms of any sleep disorder and had polysomnograms without technical recording problems.

RESULTS

Sleep architecture in preadolescent Caucasian and Hispanic children was not different between boys and girls. However, total sleep time (TST), sleep efficiency (SLE) and time spent in REM sleep declined with increasing age. In addition, the number of sleep to wake stage shifts was slightly higher in younger children. Hispanic children had less Stage 3/4 sleep (18+/-1 vs. 22+/-1%, P</=0.02) and correspondingly more Stage 2 sleep (55+/-2 vs. 50.0+/-1%, P</=0.02) than their Caucasian counterparts.

CONCLUSIONS

Using unattended home polysomnography, indices of sleep duration and architecture are not different between preadolescent boys and girls. However, with increasing age, TST and SLE decreased. In addition, there are differences in sleep architecture between Caucasians and Hispanics, which may be an important consideration in the evaluation of children with sleep disorders.

Relationship between Sleep-Disordered Breathing and Blood Pressure Levels in Community-Based Samples of Japanese Men

To examine the relationship between sleep-disordered breathing (SDB) and blood pressure levels among Japanese men, we conducted a population-based cross-sectional study of 1,424 men aged 40-69 years in rural and urban communities. The 3% oxygen desaturation index (ODI) was selected as the indicator of SDB, representing the number of desaturation events per hour of recording time in which blood oxygen fell by > or = 3% according to overnight pulse oximetry. To estimate the associations of 3% ODI levels with blood pressure levels and hypertension, multiple linear regression and logistic regression analyses were performed. The 3% ODI level was positively associated with systolic and diastolic blood pressure levels (SBP/DBP); a 5 event per hour increment of the 3% ODI level was associated with 0.8 mmHg (95% confidence interval [CI], 0.0-1.6) greater SBP and 0.7 mmHg (95% CI, 0.3-1.1) greater DBP after adjustment for age, body mass index, ethanol intake, smoking category and community. The multivariate odds ratio of hypertension for the low vs. high category of 3% ODI level was 1.63 (95% CI, 1.1-2.5). These associations were more evident among overweight than non-overweight individuals. The significant association of nocturnal oxygen desaturation with high blood pressure levels suggests that SDB plays a role in the development of hypertension among Japanese men.

Clinical outcomes associated with sleep-disordered breathing in Caucasian and Hispanic children--the Tucson Children's Assessment of Sleep Apnea study (TuCASA)

STUDY OBJECTIVES

This report describes clinical outcomes and threshold levels of respiratory disturbance index (RDI) associated with sleep-disordered breathing in children participating in the Tucson Children's Assessment of Sleep Apnea study.

DESIGN

A community-based, prospective cohort study designed to assess the severity of sleep-related symptoms associated with sleep-disordered breathing in children aged 6 to 11 years.

SETTING

Students attending elementary school in the Tucson Unified School District.

PARTICIPANTS

Unattended home polysomnograms were completed on 239 children-55.2% boys, 51% Hispanic, and 55% between the ages of 6 and 8 years.

MEASUREMENTS AND RESULTS

Based on full home polysomnography, levels of RDI that correspond to a higher prevalence of clinical symptoms of sleep-disordered breathing in children aged 6 to 11 were observed. An RDI of at least 5 was associated with frequent snoring (20.3% vs 9.1%, P<.01), excessive daytime sleepiness (22.9% vs 10.7%, P<.01), and learning problems (8.5% vs 2.5%, P<.04) when no oxygen desaturation accompanied the respiratory event. An RDI of at least 1 was associated with these symptoms when a 3% oxygen desaturation was required, snoring (24.0% vs 10.4%, P<.006), excessive daytime sleepiness (24.0% vs 13.4%, P<.04), and learning problems (10.7% vs 3.0%, P<.02). Hispanic or Caucasian ethnicity, sex, age category, obesity, insomnia, and witnessed apnea were not associated with RDI regardless of event definition.

CONCLUSIONS

The Tucson Children's Assessment of Sleep Apnea study has shown that there are values of RDI based on polysomnography that correspond to an increased rate of clinical symptoms in children ages 6 to 11 years.

Sleep-disordered breathing and cognitive impairment in elderly Japanese-American men

STUDY OBJECTIVE

To assess the association between sleep-disordered breathing and cognitive functioning in an elderly cohort of Japanese-American men.

DESIGN

Cross-sectional study.

SETTING

The Honolulu-Asia Aging Study of Sleep Apnea, Oahu, Hawaii.

PARTICIPANTS

718 men between 79 and 97 years of age examined in 1999 and 2000.

MEASUREMENTS

Apnea-hypopnea index from in-home overnight polysomnography, performance on the Cognitive Abilities Screening Instrument, body mass index, neck circumference, Epworth Sleepiness Scale, snoring, Center for Epidemiologic Studies Depression 11-item depression scale, physical disability, and history of heart disease, stroke, hypertension, diabetes, and dementia.

RESULTS

Less than 30% of the men had no sleep-disordered breathing (apnea-hypopnea index < 5) and nearly one-fifth (19%) had severe sleep-disordered breathing (apnea-hypopnea index > or = 30). Severe sleep-disordered breathing was associated with higher body mass index, habitual snoring, and daytime drowsiness. No association was found between sleep-disordered breathing and cognitive functioning, including measures of memory function, concentration, and attention.

CONCLUSIONS

Sleep-disordered breathing was associated with more drowsiness but not with poor performance on standardized cognitive tests used to screen for Alzheimer disease and other dementias in older persons. Because a healthy-participant effect may have contributed to this finding, more extensive cognitive testing may be necessary to reveal more subtle deficits from sleep-disordered breathing.

Symptoms related to sleep-disordered breathing in white and Hispanic children: the Tucson Children's Assessment of Sleep Apnea Study

STUDY OBJECTIVES

The Tucson Children's Assessment of Sleep Apnea (TuCASA) study is designed to investigate the prevalence and correlates of objectively measured sleep-disordered breathing (SDB) in preadolescent children. This article describes the parental report of sleep symptoms associated with SDB in Hispanic and white children.

DESIGN

A 13-question sleep habits screening questionnaire designed to assess the severity of sleep-related symptoms associated with SDB in children 4 to 11 years of age.

SETTING

Questionnaires were completed by the parents of children attending elementary school in the Tucson Unified School District, Tucson, AZ.

PARTICIPANTS

There were 1,494 questionnaires returned, which comprised a sample of whites (38%), Hispanics (45%), and other races (17%). Of these questionnaires, 1,214 were returned for the children of white (45.8%; 556 children) or Hispanic (54.2%; 658 children) ethnicity only. The primary analysis was completed on these 613 boys (50.5%) and 601 girls (49.5%).

RESULTS

In the total sample of 1,494 children, parents were more likely to report excessive daytime sleepiness (EDS) in female children than in male children (p <.01), however, this association did not achieve significance in the sample of only white and Hispanic children (p <.07). Composite variables for EDS and witnessed apnea (WITAP) show that parents of Hispanic children were more likely to report EDS (p <.01) and WITAP (p <.007). Hispanic children were also more likely to have learning problems (LPs) [p <.03] and to snore frequently (SN) [p <.02] than were white children. There were no significant differences between boys and girls for SN or WITAP. Hispanic boys were more likely to have reports of EDS (p <.02) and LPs (p <.04) than white boys, however, there were no other significant differences in gender or ethnicity in reports of EDS or LPs for white or Hispanic boys and girls. Those children with frequent LPs were significantly more likely to have SN (p <.001), EDS (p <.001), and WITAP (p <.001). A logistic regression model predicting LP resulted in significant adjusted odds ratios (ORs) of 2.4 for SN, 2.5 for EDS, and 2.1 for children aged 8 to 11 years. A similar model for EDS resulted in significant adjusted ORs of 3.2 for SN, 5.7 for WITAP, and 1.6 for female gender. Ethnicity was not significant in either model.

CONCLUSIONS

Hispanic children in the population-based TuCASA study experienced more frequent symptoms associated with SDB, such as SN, EDS, WITAP, and LPs, than did white children. Children with LPs are 2.4 times more likely to have SN, 2.5 times more likely to have EDS, and were 2.1 times more likely to be between the ages of 8 and 11 years. Children with EDS were 3.2 times more likely to have SN, 5.7 times more likely to have WITAP, and were 1.6 times more likely to be a girl.

The utility of cephalometry with the Muller maneuver in evaluating the upper airway and its surrounding structures in Chinese patients with sleep-disordered breathing

OBJECTIVE

The objective was to simultaneously measure the size and collapsibility of the upper airway in Chinese patients with sleep-disordered breathing using cephalometry with the Muller maneuver.

STUDY DESIGN

Prospective study of 100 consecutive Chinese patients evaluated for sleep-disordered breathing at a sleep center.

METHODS

Each patient received overnight polysomnography and two lateral cephalograms (at the end-expiration phase and the Muller maneuver, respectively) to evaluate the upper airway and its surrounding structures (soft palate, tongue, and hyoid bone). After excluding 15 subjects from this study because of unclear cephalograms, 85 patients with sleep-disordered breathing were enrolled, including 32 with snoring or mild obstructive sleep apnea and 53 with moderate to severe obstructive sleep apnea.

RESULTS

Patients with varying degrees of severity of sleep-disordered breathing significantly differed in terms of the structure and function of the upper airway and the surrounding structures. The Muller maneuver may result in dynamic changes in the retropalatal airway and pharyngeal length, and the levels of dynamic changes were related to the severity of sleep-disordered breathing. Pearson correlation analysis revealed that the decrease in the minimum retropalatal dimension during the Muller maneuver in patients with snoring or with mild obstructive sleep apnea was related to the thickening of the soft palate and posterior displacement of tongue. Meanwhile, the decrease in the minimum retropalatal dimension in patients with moderate to severe obstructive sleep apnea was related to lengthening of the soft palate, increased tongue height, and downward displacement of the tongue and hyoid bone.

CONCLUSION

Cephalometry with the Muller maneuver may provide further insight into the pathogenesis of various levels of severity of sleep-disordered breathing.

Variation in symptoms of sleep-disordered breathing with race and ethnicity: the Sleep Heart Health Study

STUDY OBJECTIVES

To examine the relation of sleep-related symptoms to race and ethnicity in a diverse sample of middle-aged and older men and women.

DESIGN

Cross-sectional questionnaire survey.

SETTING

In the initial phase of the Sleep Heart Health Study, men and women enrolled in participating epidemiologic cohort studies were surveyed.

PARTICIPANTS

13,194 men and women 40 years of age and older, including 11,517 non-Hispanic white, 648 black, 643 American Indian, 296 Hispanic, and 90 Asian-Pacific Islander.

INTERVENTIONS

Not applicable.

MEASUREMENTS AND RESULTS

After adjustment for BMI and other factors, frequent snoring was more common among Hispanic women (odds ratio (OR) = 2.25, 95% confidence interval (CI) = 1.48, 3.42) and black women (OR = 1.55, 95% Ci = 1.13, 2.13) than among non-Hispanic white women. Hispanic men were significantly more likely to report frequent snoring than non-Hispanic white men (OR = 2.30, 95% CI = 1.43, 3.69). Black, American Indian, and Asian men did not differ significantly from white men in snoring prevalence. American Indian women were significantly more likely to report breathing pauses during sleep than their white, non-Hispanic counterparts (OR = 1.52, 95% CI 1.03, 2.24), although polysomnography data on a subset of the sample suggested that the association between this symptom reported on questionnaire and objective evidence of sleep-disordered breathing may be weaker among American Indians than among other groups. Mean Epworth Sleepiness Scale scores were slightly higher in black men and women than in their white, non-hispanic counterparts.

CONCLUSIONS

Frequent snoring was more common among black and Hispanic women and Hispanic men than among their white non-Hispanic counterparts, even after adjusting for BMI and other factors. Further research including polysomnography and objective measurements of sleepiness is needed to assess the physiologic and clinical significance of these findings.

School performance, race, and other correlates of sleep-disordered breathing in children

OBJECTIVES

Childhood sleep-disordered breathing (SDB) has been associated with poor school performance. Both problems are common among African-American (AA) children, but potential confounders such as low socioeconomic status (SES) and obesity have not been well studied.

METHODS

Children in second and fifth grades at six urban elementary schools were evaluated by teachers' ratings and year-end reading and math assessments. Risk for SDB was assessed with the validated parental Pediatric Sleep Questionnaire, and SES by qualification for school lunch assistance.

RESULTS

Among 146 children whose parents completed surveys, risk for SDB was associated with AA race, low SES, and poor teacher ratings (P<0.01), but not assessment scores (P>0.1). In multiple regression models, poor school performance was consistently and independently predicted by low SES (P<0.01) but not by AA race or SDB risk. Risk for SDB was associated with low SES before, but not after body mass index (BMI) was taken into account.

CONCLUSIONS

The SDB symptoms, AA race, and low SES all vary to some extent with poor school performance, but the only consistent and independent covariate of performance is SES. Risk for SDB is associated with low SES, perhaps because of a third variable, namely high BMI.

The effect of race and sleep-disordered breathing on nocturnal BP "dipping": analysis in an older population

STUDY OBJECTIVES

BP normally drops (or "dips") by approximately 10% at nighttime; however, in a number of illnesses there is an increased amount of "nondipping" of nocturnal BP. This study examined whether nondipping in older African Americans and older white subjects is related to the presence of sleep-disordered breathing (SDB) and hypertension.

DESIGN

Prospective study with a convenience sample.

SETTING

All data were collected in the subjects' homes.

PARTICIPANTS

Seventy self-defined African Americans with complaints of snoring or excessive daytime sleepiness, and 70 age-matched and gender-matched white subjects.

MEASUREMENTS AND RESULTS

Sleep was recorded for 2 nights, with 1 night of oximetry. BP was recorded on a separate 24-h period. African Americans had higher dipping ratios than white subjects even after accounting for covariates such as respiratory disturbance index (RDI), oxygen desaturation index (ODI), body mass index, and average 24-h mean arterial pressure (p = 0.025). Higher values of RDI (R(2) = 0.0686, p = 0.021) and ODI (R(2) = 0.042, p < 0.03) were correlated with higher dipping ratios in both African Americans and white subjects. However, there was a three-way interaction such that higher RDIs were correlated primarily with nondipping in African Americans receiving antihypertensive medication (R(2) = 0.0373, p = 0.022).

CONCLUSIONS

These results demonstrated that African Americans tend to be "nondippers," while white subjects tended to be "dippers." This nondipping was not a result of weight, gender, or of having SDB. The analyses also confirmed that, in both races, the dipping ratio was greatest in those with SDB and hypertension. The third hypothesis, that RDI would be greatest in the nondipping hypertensive subjects, was true only for the African Americans.

Are there ethnic differences in sleep architecture?

The possibility of ethnic differences in sleep architecture was initially examined in conjunction with studies of sleep apnea (study 1). This possibility was then examined in another cohort of patients to determine whether the results might generalize (study 2). Polysomnography was obtained in both cohorts as part of larger protocols investigating sympathetic nervous system activity, blood pressure, and sleep. Sleep monitoring took place in an inpatient clinical research center of a university hospital. Study 1 focused on sleep apnea physiology and involved volunteers with sleep apnea who were otherwise healthy. Study 2 focused on differences in stress reactivity between American Black and White subjects and involved hypertensive and normotensive volunteers who were otherwise healthy. Analyses include 61 participants from study 1 and 35 participants from study 2. Ethnicity in both cohorts was determined by self-report. Participants in both studies were monitored during sleep with traditional polysomnography including electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), and oximetry. In Study 1, Blacks had longer TST (P < 0.01), more REM sleep (P < 0.05), and less WASO (P < 0.05) than Whites. After controlling for RDI, Blacks had longer TST and spent a smaller percentage of time in deep sleep (P < 0.05). In study 2, Blacks had longer TST and REM sleep, lower percent deep sleep, and lower percent deep sleep controlling for RDI (P < 0.05). In two separate studies, Blacks had longer TST, more minutes of REM, and lower percentage deep sleep. These findings suggest possible ethnic differences in sleep architecture.

Sleep apnea and health-related quality of life in African-American elderly

The relationship between health-related quality of life (HRQOL) and sleep apnea was examined in a sample of elderly African-Americans screened for snoring and daytime sleepiness. Seventy African-Americans over the age of 65 years completed a comprehensive sleep questionnaire, the Quality of Well-Being Scale (QWB), and the Medical Outcomes Study (MOS) Core Measures of HRQOL (116-item Long Version) and had sleep recorded. Those with moderate-severe sleep apnea had significantly lower Physical Component summary scores than those with no sleep apnea (p < 0.05). After controlling for medical conditions, sleep apnea was significantly related to both general physical functioning and general mental health functioning in those with mild apnea (apnea-hypopnea index [AHI] < 15), but not in those with moderate to severe apnea. There was an initial decrease in HRQOL up to an AHI level of 15, at which point HRQOL remained at a lowered level. The QWB scores of our sleep apnea sample were similar to the QWB scores found in patients with depression and chronic obstructive pulmonary disease (COPD), suggesting that sleep disturbances may impact daily living and health as much as other medical conditions.

Computed tomographic cephalometric analysis of Chinese patients with obstructive sleep apnoea

Variations of craniofacial and upper airway structures are recognized to contribute to the phenomenon of obstructive sleep apnoea (OSA). Most previous cephalometric studies were performed using erect lateral radiographs in Caucasian patients. The present project aims to determine cephalometric measurements, utilizing CT, in normal Chinese subjects and in Chinese patients with OSA. Computed tomography of 25 patients with OSA (proven using overnight polysomnography), and of 25 age-, sex-, height-, bodyweight- and body mass index (BMI)-matched control subjects were prospectively performed. Thirteen standard bony and soft-tissue measurements were obtained from the CT lateral scout view of the head and neck, taken with each subject in the neutral supine position. The cross-sectional area was calculated at two axial levels (velopharynx and hypopharynx). The measurements in the two groups, OSA and control subjects, were compared. The measurements for hyoid position (P = 0.00), nasal cavity length (P = 0.01), mandibular prognathism (P = 0.05), tongue size (P = 0.02), oropharyngeal airway space (P = 0.02), posterior tongue airway space (P = 0.04) and cross-sectional areas at the level of the velopharynx (P = 0.00) and hypopharynx (P = 0.01) differed significantly between the two groups. In conclusion, CT cephalometric measurements show that certain anatomical variations in the head and neck are likely to contribute to the pathogenesis of OSA in Chinese patients.

Epidemiology and pathogenesis of sleep-disordered breathing

Sleep-disordered breathing is common in the general population, but the observed prevalence depends on the criteria used to establish the diagnosis. Obesity is a strong risk factor, but other conditions such as allergic upper and lower airways disease may also be important. Differences in risk between the sexes and ethnic groups appear to be present even after established risk factors have been considered. The pathogenesis is likely mutifactorial with anatomic and physiologic factors of varying importance in different individuals. The natural history is uncertain, but without treatment or reduction in risk factors, some progression is likely. Ongoing epidemiologic investigations such as the Sleep Heart Health Study are beginning to provide important information on these questions.

Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study

CONTEXT

Sleep-disordered breathing (SDB) and sleep apnea have been linked to hypertension in previous studies, but most of these studies used surrogate information to define SDB (eg, snoring) and were based on small clinic populations, or both.

OBJECTIVE

To assess the association between SDB and hypertension in a large cohort of middle-aged and older persons.

DESIGN AND SETTING

Cross-sectional analyses of participants in the Sleep Heart Health Study, a community-based multicenter study conducted between November 1995 and January 1998.

PARTICIPANTS

A total of 6132 subjects recruited from ongoing population-based studies (aged > or = 40 years; 52.8% female).

MAIN OUTCOME MEASURES

Apnea-hypopnea index (AHI, the average number of apneas plus hypopneas per hour of sleep, with apnea defined as a cessation of airflow and hypopnea defined as a > or = 30% reduction in airflow or thoracoabdominal excursion both of which are accompanied by a > or = 4% drop in oxyhemoglobin saturation) [corrected], obtained by unattended home polysomnography. Other measures include arousal index; percentage of sleep time below 90% oxygen saturation; history of snoring; and presence of hypertension, defined as resting blood pressure of at least 140/90 mm Hg or use of antihypertensive medication.

RESULTS

Mean systolic and diastolic blood pressure and prevalence of hypertension increased significantly with increasing SDB measures, although some of this association was explained by body mass index (BMI). After adjusting for demographics and anthropometric variables (including BMI, neck circumference, and waist-to-hip ratio), as well as for alcohol intake and smoking, the odds ratio for hypertension, comparing the highest category of AHI (> or = 30 per hour) with the lowest category (< 1.5 per hour), was 1.37 (95% confidence interval [CI], 1.03-1.83; P for trend = .005). The corresponding estimate comparing the highest and lowest categories of percentage of sleep time below 90% oxygen saturation (> or = 12% vs < 0.05%) was 1.46 (95% CI, 1.12-1.88; P for trend <.001). In stratified analyses, associations of hypertension with either measure of SDB were seen in both sexes, older and younger ages, all ethnic groups, and among normal-weight and overweight individuals. Weaker and nonsignificant associations were observed for the arousal index or self-reported history of habitual snoring.

CONCLUSION

Our findings from the largest cross-sectional study to date indicate that SDB is associated with systemic hypertension in middle-aged and older individuals of different sexes and ethnic backgrounds.

A comparison of Asian and white patients with obstructive sleep apnea syndrome

OBJECTIVE

To evaluate the possible differences between Asian and white patients with obstructive sleep apnea syndrome.

METHODS

A retrospective review of Asian and white patients during a 12-month period was conducted. Patients with respiratory disturbance index (RDI) > or = 15 based on polysomnography were included in the study. Variables examined include age, sex, body mass index (BMI), RDI, lowest oxygen saturation (LSAT), and cephalometric analysis data.

RESULTS

Fifty-eight Asian patients (53 men) and 293 white patients (260 men) were studied. The Asians were younger (44.1 +/- 9.8 vs. 47.5 +/- 11.6 y, P = .02), and the mean BMI (kg/m2) was 26.6 +/- 3.7 in the Asians and 30.7 +/- 5.9 in the whites (P < .001). The mean RDI was similar (56.6 +/- 34.9 vs. 55.6 +/- 26.9, P = NS), but the mean LSAT was lower in the whites (77.7 +/- 9.9% vs. 70.0 +/- 15.6%, P < .001). Based on the cephalometric data, the Asians have maxillomandibular protrusion, narrower cranial base angle, larger posterior airway space, and more superiorly positioned hyoid bone compared with the whites.

CONCLUSIONS

Although male gender was found to be an important risk factor for obstructive sleep apnea syndrome in both Asian and white patients, obesity may be a less significant risk factor in the Asians because the majority of our Asian patients were nonobese. There was also variability in the craniomandibular factors that contributed to obstructive sleep apnea syndrome in the two groups.

Snoring & sleep apnea: a population study in Italian women

The aim of this cross-sectional study was to evaluate the prevalence of sleep-disordered breathing by means of a validated portable instrument (MESAM IV) and to investigate the relationship between snoring and sleep apnea in a sample of Italian middle-aged female population. We randomly chose 750 subjects aged 40 to 65 years and 365 agreed to participate to the study. In this group, 19.7% of subjects were every-night snorers according to the questionnaire; when recorded, 54.2% snored for more than 10% of the night, and 7.1% for more than 50% of the night. Sleep apnea was also common: 10.7% of subjects had a respiratory disturbances per hour (RDI) between 5 and 9, 7.7% an RDI between 10 and 19, and 2.2% had an RDI > or =20. Snoring percentage and RDI were significantly correlated. However, 50% of subjects who snored for more than half the night had no evidence of sleep apnea. Snoring amount >50% resulted influenced by body mass index, while RDI>10 was influenced by neck diameter. We concluded that in middle-aged women, both snoring and sleep apnea are very common. A high percentage of snoring is not essential for the occurrence of sleep apnea, nor it necessarily indicates the presence of sleep apnea.

Risk factors for sleep-disordered breathing in children. Associations with obesity, race, and respiratory problems

This study examined risk factors for sleep-disordered breathing (SDB) in children and adolescents; specifically, quantifying risk associated with obesity, race, and upper and lower respiratory problems. Subjects were participants in a genetic-epidemiologic study of SDB and included 399 children and adolescents 2 to 18 yr of age, recruited as members of families with a member (a proband) with known sleep apnea (31 index families) or as members of neighborhood control families (30 families). SDB was assessed with home overnight multichannel monitoring and SDB was defined based on an apneahypopnea index >/= 10 (moderately affected) or < 5 (unaffected). SDB of moderate level was significantly associated with obesity (odds ratio, 4.59; 95% confidence interval [CI], 1.58 to 13.33) and African-American race (odds ratio, 3.49; 95% CI, 1.56 to 8.32) but not with sex or age. After adjusting for obesity, proband sampling, race and familial clustering, sinus problems and persistent wheeze each independently (of the other) predicted SDB. These data suggest the importance of upper and lower respiratory problems and obesity as risk factors for SDB in children and adolescents. Increased risk in African Americans appears to be independent of the effects of obesity or respiratory problems.

Ethnicity, obstructive sleep apnoea and ischaemic heart disease

We studied the relationship between different ethnic groups, obstructive sleep apnoea (OSA) and ischaemic heart disease. Four hundred and thirty-two inpatients from the medical wards were interviewed. Limited overnight sleep studies were done in 129 of those who had habitual snoring, daytime sleepiness based on an Epworth sleepiness scale of 8 or more, or a large neck size of 40 cm or more. There were 315 Chinese (72.9%), 67 Malays (15.5%), 43 Indians (10%) and 3 from other races (1.4%). The prevalence of OSA was 19.7%, 30% and 12% among the Chinese, Malays and Indians, respectively. The prevalence ratio for OSA was 1.52 in Malays using Chinese patients as the baseline (P = 0.07). The median neck circumference was 37 cm in both racial groups. The median body mass index was 22.7 kg/m2 in Chinese compared to 23.6 kg/m2 in Malays. The median apnoea-hypopnoea index was 22.7, 19.0 and 26.9 events/hour among the Chinese, Malays and Indians, respectively. OSA was independently associated with the prevalence of IHD (adjusted prevalence ratio 1.68; 95% CI: 1.15, 2.46; P = 0.009). The prevalence of ischaemic heart disease (IHD) was 31%, 24% and 28% in Chinese, Malays and Indians, respectively. The prevalence ratio for IHD in Malays compared to Chinese was 0.77. After adjusting for OSA, there was an even greater reduction in the risk of IHD (adjusted prevalence ratio 0.70). This suggests that OSA is a confounder in the relationship between race and ischaemic heart disease.

Comparative clinical and physiological features of Maori, Pacific Islanders and Europeans with sleep related breathing disorders

Recent studies have suggested that there is a familial association of sleep apnoea syndrome and that this is not entirely explained by inheritance of known risk factors. Maori (M) and Pacific Islanders (PI) have many of the body habitus features associated with sleep apnoea and therefore might be expected to exhibit more severe disease than Europeans (E).

OBJECTIVE

To compare the clinical and physiological characteristics of the different ethnic groups and to determine if race was an independent predictor of severity of sleep apnoea.

METHODOLOGY

A prospective evaluation of patients attending the Sleep Disordered Breathing Clinic which serves the whole of Auckland (population 1.1 million), New Zealand was conducted for the period July 1994 to August 1995. The evaluation included history including a 26 question questionnaire, Epworth sleepiness score, examination, and where indicated, full polysomnography.

RESULTS

A total of 233 patients (154 E, 48 M and 33 PI), underwent full polysomnography. Forty-one (85%) of the M and 31 (94%) of PI had obstructive or mixed sleep apnoea compared with only 74 (49%) of the E (P < 0.0001; chi 2). There were few racial differences in the responses to the sleep questionnaire. M and PI were shown to have much greater neck and waist circumference and body mass indices. Severity parameters (apnoea-hypopnoea index, wake and minimum oxygen saturation, and apnoea duration) were greater for both M and PI compared with E (P < 0.001; Mann-Whitney U-test). Stepwise regression identified neck size, body mass index and age as independent predictors of severity.

CONCLUSION

When other factors were controlled for, race was not an important independent predictor of severity of sleep apnoea.

Prevalence of snoring and sleep breathing-related disorders in Chinese, Malay and Indian adults in Singapore

This study investigated the prevalence of snoring and symptoms of sleep breathing-related disorders in the multi-ethnic population of Singapore (3 million people, comprising 75% Chinese, 15% Malay and 7% Indian). A multistaged, area cluster, disproportionate stratified, random sampling of adults aged 20-74 yrs was used to obtain a sample of 2,298 subjects (65% response), with approximately equal numbers of Chinese, Malay and Indian and in each 10 yr age group. An interviewer-administered field questionnaire was used to record symptoms of snoring and breathing disturbances during sleep witnessed by a room-mate and other personal and health-related data. The weighted point estimate (and 95% confidence interval) of the whole population prevalence of snoring was 6.8% (53-83). There were pronounced ethnic differences among Chinese, 6.2% (4.4-8.1); Malay, 8.1% (6.1-10.2) and Indian, 10.9% (85-13.4). The minimum whole population prevalence by the most restricted symptom criteria for defining sleep breathing-related disorder was 0.43% (0.05-0.8%). Similar marked ethnic differences in rates were observed using various symptom criteria. The ethnic differences in sleep breathing symptoms paralleled the differences in body mass index, neck circumference and hypertension, but statistically significant differences remained after adjustment for sex, age and these known associated factors. Marked ethnic differences in snoring and sleep breathing-related disorders were observed in Chinese, Malays and Indians in Singapore, which were only partly explained by known factors of sex, age and body habitus.