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

Phenotypic Subtypes of OSA: A Challenge and Opportunity for Precision Medicine

Current strategies for the management of OSA reflect a one-size-fits-all approach. Diagnosis and severity of OSA are based on the apnea-hypopnea index and treatment initiated with CPAP, followed by trials of alternatives (eg, oral appliances) if CPAP "fails." This approach does not consider the heterogeneity of individuals with OSA, reflected by varying risk factors, pathophysiological causes, clinical manifestations, and consequences. Recently, studies using analytic approaches such as cluster analysis have taken advantage of this heterogeneity to identify OSA phenotypes, or subtypes of patients with unique characteristics, that may enable more personalized approaches to prognostication and treatment. Examples include symptom-based subtypes such as "excessively sleepy" and "disturbed sleep" with differing impact of CPAP on symptoms and health-related quality of life. Polysomnographic subtypes, distinguished by respiratory event association with hypoxemia, arousals, or both, exhibit varying risks of cardiovascular disease and response to therapy. This review summarizes the findings from recent cluster analysis studies in sleep apnea and synthesizes common themes to describe the potential role (and limitations) of phenotypic subtypes in precision medicine for OSA. It also highlights future directions, including linking of phenotypes to clinically relevant outcomes, rigorous and transparent assessment of phenotype reproducibility, and need for tools that categorize patients into subtypes, to prospectively validate phenotype-based prognostication and treatment approaches. Finally, we highlight the critical need to include women and more racially/ethnically diverse populations in this area of research if we are to leverage the heterogeneity of OSA to improve patient lives.

Nondipping Nocturnal Blood Pressure Predicts Sleep Apnea in Patients With Hypertension

STUDY OBJECTIVES

Systemic hypertension is highly prevalent in obstructive sleep apnea (OSA) but there are limited data on OSA prevalence in cohorts with hypertension comparing dippers and nondippers. We investigated this relationship in a clinic-based cohort of patients with hypertension who were not screened for any pretest possibility of OSA.

METHODS

A total of 100 patients with hypertension aged (mean ± SD) 58 ± 10 years, body mass index 30.5 ± 6.1 kg/m2, and Epworth Sleepiness Scale score 6 ± 4 were included. All underwent overnight attended sleep studies and 24-hour ambulatory blood pressure monitoring. The primary study end-point was OSA prevalence based on the standard criteria of apnea-hypopnea index (AHI) ≥ 15 events/h in patients with dipping and nondipping nocturnal blood pressure.

RESULTS

Results showed 10.5% of dippers and 43.5% of nondippers had an AHI ≥ 15 (chi-square P = .001). In univariate analysis, AHI correlated significantly with blood pressure dip (r = -.26, P < .05), as did ESS (r = -.28, P < .05). In linear regression, AHI predicted the magnitude of blood pressure dip (standardised β = -.288, P = .03), whereas age, body mass index, systolic blood pressure and diastolic blood pressure did not.

CONCLUSIONS

Patients with nondipping nocturnal blood pressure are at high risk of OSA, regardless of symptom profile, which supports the recommendation that such patients should be assessed for co-existing OSA.

Disparities in Hypertension Among African-Americans: Implications of Insufficient Sleep

PURPOSE OF REVIEW

Sleep deficiency has been proposed as a potential contributor to racial disparities in cardiovascular health. We present contemporary evidence on the unequal burden of insufficient sleep in Blacks/African-Americans and the repercussions for disparate risk of hypertension.

RECENT FINDINGS

The prevalence of insufficient sleep is high and rising and has been recognized as an important cardiovascular risk factor. Presumably due to a constellation of environmental, psychosocial, and individual determinants, these risks appear exacerbated in Blacks/African-Americans, who are more likely to experience short sleep than other ethnic/racial groups. Population-based data suggest that the risk of hypertension associated with sleep deficiency is greater in those of African ancestry. However, there is a paucity of experimental evidence linking short sleep duration to blood pressure levels in African-Americans. Blacks/African-Americans may be more vulnerable to sleep deficiency and to its hypertensive effects. Future research is needed to unequivocally establish causality and determine the mechanism underlying the postulated racial inequalities in sleep adequacy and consequent cardiovascular risk.

Genetic Ancestry for Sleep Research: Leveraging Health Inequalities to Identify Causal Genetic Variants

Recent evidence has highlighted the health inequalities in sleep behaviors and sleep disorders that adversely affect outcomes in select populations, including African-American and Hispanic-American subjects. Race-related sleep health inequalities are ascribed to differences in multilevel and interlinked health determinants, such as sociodemographic factors, health behaviors, and biology. African-American and Hispanic-American subjects are admixed populations whose genetic inheritance combines two or more ancestral populations originating from different continents. Racial inequalities in admixed populations can be parsed into relevant groups of mediating factors (environmental vs genetic) with the use of measures of genetic ancestry, including the proportion of an individual's genetic makeup that comes from each of the major ancestral continental populations. This review describes sleep health inequalities in African-American and Hispanic-American subjects and considers the potential utility of ancestry studies to exploit these differences to gain insight into the genetic underpinnings of these phenotypes. The inclusion of genetic approaches in future studies of admixed populations will allow greater understanding of the potential biological basis of race-related sleep health inequalities.

Prevalence and Predictors of Arrhythmia in Patients with Obstructive Sleep Apnea

Objectives

To assess the prevalence and types of arrhythmias in Saudi OSA patients and to identify predictors of arrhythmia in this group of patients.

Methods

This case-control study included all patients who underwent level I attended overnight polysomnography between 2009 and 2012. Electrocardiographic data collected during sleep studies of patients with and without OSA were manually reviewed.

Results

The study comprised 498 patients (394 OSA patients and 104 non-OSA patients (controls). The prevalence of arrhythmia in OSA patients was higher than that in the controls (26.9% vs. 11.5%; p=0.001). Comparing OSA patients and controls showed: premature atrial contraction (10.2%vs.2.9%;p=0.019), premature ventricular contraction (PVC) (19.3%vs.9.6%;p=0.02), non-isolated PVC (bi/tri/qua) 10.8%vs.2.3%;p=0.04) and atrial fibrillation (1.6%vs.0%;p=0.001). Multiple logistic regression analysis revealed that, patients with OSA had twice the odds of having any cardiac arrhythmia (OR 1.91; CI 95% 1.27-3.11; p <0.05).

Conclusions

Patients with OSA had a higher prevalence of arrhythmia compared to controls, and OSA is a predictor of arrhythmia during sleep.

Evaluation of tolerance to ambulatory blood pressure monitoring: Analysis of dipping profile in a large cohort of hypertensive patients

Ambulatory blood pressure monitoring (ABPM) is a helpful tool to comprehensively identify and diagnose arterial hypertension. Moreover, it allows to better identify alterations in the circadian BP profile, as the nocturnal "nondipping" status, characterized by a lack of the physiological 10% night BP reduction and associated with a greater risk of target organ damage. However, ABPM has some limitations such as restricted availability, discomfort, particularly at night, cost implications, and reproducibility.Aim of the study was evaluate if the "nondipping" phenomenon may be related to low degree of tolerance to ABPM. Additionally, to determine whether self-reported events of sleep disorders and nighttime urinations may affect the "nondipping" status.From January 2013 to December 2015, we consecutively evaluated 1046 patients with arterial hypertension, performing ABPM, considering a tolerance index calculated on the basis of the patients' responses to a questionnaire.Thirty-eight out of 1046 patients showed complete lack of tolerance to the instrument during the day, whilst 126 during the night. There were no statistically significant differences in daytime and nighttime values of tolerance to the instrument between "dippers" and "nondippers," between "extreme-dippers" and the remaining patients or between "reverse-dippers" and the remaining patients. There were no statistically significant differences in the number of nocturnal awakenings between the groups. However, we found that the number of awakenings followed by urination was higher in "nondipping" patients and in "reverse-dipping" patients compared to the other groups.We found that the poor tolerance to the instrument does not seem to influence the BP "dipping" phenomenon among hypertensive individuals. Moreover, we think that in the evaluation of the ABPM data, factors, such as nocturnal urination and sleep disorders, need to be carefully taken into account, since may lead to a higher incidence of "nondipping" pattern.

Clinic and ambulatory blood pressure in a population-based sample of African Americans: the Jackson Heart Study

Blood pressure (BP) can differ substantially when measured in the clinic versus outside of the clinic setting. Few population-based studies with ambulatory blood pressure monitoring (ABPM) include African Americans. We calculated the prevalence of clinic hypertension and ABPM phenotypes among 1016 participants in the population-based Jackson Heart Study, an exclusively African-American cohort. Mean daytime systolic BP was higher than mean clinic systolic BP among participants not taking antihypertensive medication (127.1[standard deviation 12.8] vs. 124.5[15.7] mm Hg, respectively) and taking antihypertensive medication (131.2[13.6] vs. 130.0[15.6] mm Hg, respectively). Mean daytime diastolic BP was higher than clinic diastolic BP among participants not taking antihypertensive medication (78.2[standard deviation 8.9] vs. 74.6[8.4] mm Hg, respectively) and taking antihypertensive medication (77.6[9.4] vs. 74.3[8.5] mm Hg, respectively). The prevalence of daytime hypertension was higher than clinic hypertension for participants not taking antihypertensive medication (31.8% vs. 14.3%) and taking antihypertensive medication (43.0% vs. 23.1%). A high percentage of participants not taking and taking antihypertensive medication had nocturnal hypertension (49.4% and 61.7%, respectively), white-coat hypertension (30.2% and 29.3%, respectively), masked hypertension (25.4% and 34.6%, respectively), and a nondipping BP pattern (62.4% and 69.6%, respectively). In conclusion, these data suggest hypertension may be misdiagnosed among African Americans without using ABPM.

Sleep Disturbances among Older Adults in the United States, 2002-2012: Nationwide Inpatient Rates, Predictors, and Outcomes

Objective/Background: We examined the rates, predictors, and outcomes [mortality risk (MR), length of stay (LOS), and total charges (TC)] of sleep disturbances in older hospitalized patients.

Patients/Methods: Using the U.S. Nationwide Inpatient Sample database (2002–2012), older patients (≥60 years) were selected and rates of insomnia, obstructive sleep apnea (OSA) and other sleep disturbances (OSD) were estimated using ICD-9CM. TC, adjusted for inflation, was of primary interest, while MR and LOS were secondary outcomes. Multivariable regression analyses were conducted.

Results: Of 35,258,031 older adults, 263,865 (0.75%) had insomnia, 750,851 (2.13%) OSA and 21,814 (0.06%) OSD. Insomnia rates increased significantly (0.27% in 2002 to 1.29 in 2012, P-trend < 0.001), with a similar trend observed for OSA (1.47 in 2006 to 5.01 in 2012, P-trend < 0.001). TC (2012 $) for insomnia-related hospital admission increased over time from $22,250 in 2002 to $31,527 in 2012, and increased similarly for OSA and OSD; while LOS and MR both decreased. Women with any sleep disturbance had lower MR and TC than men, while Whites had consistently higher odds of insomnia, OSA, and OSD than older Blacks and Hispanics. Co-morbidities such as depression, cardiovascular risk factors, and neurological disorders steadily increased over time in patients with sleep disturbances.

Conclusion: TC increased over time in patients with sleep disturbances while LOS and MR decreased. Further, research should focus on identifying the mechanisms that explain the association between increasing sleep disturbance rates and expenditures within hospital settings and the potential hospital expenditures of unrecognized sleep disturbances in the elderly.

Determinants of day-night difference in blood pressure, a comparison with determinants of daytime and night-time blood pressure

Blunted day–night difference in blood pressure (BP) is an independent cardiovascular risk factor, although there is limited information on determinants of diurnal variation in BP. We investigated determinants of day–night difference in systolic (SBP) and diastolic (DBP) BP and how these compared with determinants of daytime and night-time SBP and DBP. We analysed the association of mean daytime, mean night-time and mean day–night difference (defined as (mean daytime−mean night-time)/mean daytime) in SBP and DBP with clinical, lifestyle and biochemical parameters from 1562 adult individuals (mean age 38.6) from 509 nuclear families recruited in the GRAPHIC Study. We estimated the heritability of the various BP phenotypes. In multivariate analysis, there were significant associations of age, sex, markers of adiposity (body mass index and waist–hip ratio), plasma lipids (total and low-density lipoprotein cholesterol and triglycerides), serum uric acid, alcohol intake and current smoking status on daytime or night-time SBP and/or DBP. Of these, only age (P=4.7 × 10⁻⁵), total cholesterol (P=0.002), plasma triglycerides (P=0.006) and current smoking (P=3.8 × 10⁻⁹) associated with day–night difference in SBP, and age (P=0.001), plasma triglyceride (P=2.2 × 10⁻⁵) and current smoking (3.8 × 10⁻⁴) associated with day–night difference in DBP. 24-h, daytime and night-time SBP and DBP showed substantial heritability (ranging from 18–43%). In contrast day–night difference in SBP showed a lower heritability (13%) while heritability of day–night difference in DBP was not significant. These data suggest that specific clinical, lifestyle and biochemical factors contribute to inter-individual variation in daytime, night-time and day–night differences in SBP and DBP. Variation in day–night differences in BP is largely non-genetic.

Effectiveness of continuous positive airway pressure in lowering blood pressure in patients with obstructive sleep apnea: a critical review of the literature

Obstructive sleep apnea (OSA) is an extremely common comorbid condition in patients with hypertension, with a prevalence of ~50%. There is growing evidence suggesting that OSA is a secondary cause of hypertension, associated with both poor blood pressure (BP) control and target organ damage in patients with hypertension. The application of continuous positive airway pressure (CPAP) during sleep is the gold standard treatment of moderate- to-severe OSA and very effective in abolishing obstructive respiratory events. However, several meta-analyses showed that the overall impact of CPAP on BP is modest (~2 mmHg). There are several potential reasons for this disappointing finding, including the heterogeneity of patients studied (normotensive patients, controlled, and uncontrolled patients with hypertension), non-ideal CPAP compliance, clinical presentation (there is some evidence that the positive impact of CPAP on lowering BP is more evident in sleepy patients), and the multifactorial nature of hypertension. In this review, we performed a critical analysis of the literature evaluating the impact of CPAP on BP in several subgroups of patients. We finally discussed perspectives in this important research area, including the urgent need to identify predictors of BP response to CPAP and the importance of precision medicine in this scenario.

Relationship Between OSA and Hypertension

There is a bidirectional association between OSA and systemic hypertension. The strengths of this relationship appear to be modulated by factors such as age, sex, and somnolence. The 24-h BP circadian pattern also appears to be influenced by OSA. Patients with this syndrome exhibit a high prevalence of nondipping or riser circadian patterns, which are related to clinical and subclinical organ damage in the heart and brain. However, the influence of OSA on nocturnal hypertension development has not yet been clarified. A special area of interest is the recognized relationship between OSA and resistant hypertension. The majority of patients with resistant hypertension suffer OSA. CPAP treatment significantly reduces BP in such patients and could play a clinical role in the management of BP in these patients. Several meta-analyses have demonstrated a concordant mild effect of CPAP on systemic hypertension. This effect is related to CPAP compliance, somnolence status, and baseline BP. The effects of oral appliances on BP in patients with OSA must be evaluated in randomized controlled trials. In the absence of additional data reported by clinical studies on other antihypertensive drug treatments, diuretics, particularly antialdosteronic diuretic agents, should be considered the first-line antihypertensive drug treatment in patients with OSA. By reducing parapharyngeal edema and secondary upper airway obstruction, these drugs appear to improve OSA severity and also to reduce BP.

Use of continuous positive airway pressure for sleep apnea in the treatment of hypertension

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) and hypertension are highly prevalent and treatable conditions that often coexist and both contribute to an increased cardiovascular risk. The ability of continuous positive airway pressure (CPAP) to improve blood pressure in hypertensive patients with OSA is debated. This review highlights findings from recent studies that have investigated the impact of CPAP on blood pressure in patients with OSA.

RECENT FINDINGS

Comparing the results of various studies is complicated by important methodological differences among them. In hypertensive patients with OSA, treatment with CPAP improves blood pressure to a smaller degree than that derived from antihypertensive medication. Patients with more severe OSA and with greater adherence to CPAP are likely to gain the most benefit from the therapy.

SUMMARY

CPAP should be used in combination with antihypertensive medications in hypertensive patients with OSA. CPAP has the additional benefits of restoring nocturnal dipping and improving arterial stiffness, thus potentially influencing cardiovascular morbidity in these high-risk patients.

Disparities and genetic risk factors in obstructive sleep apnea

Obstructive sleep apnea (OSA) is an increasingly prevalent condition. A growing body of literature supports substantial racial disparities in the prevalence, risk factors, presentation, diagnosis, and treatment of this disease. Craniofacial structure among Asians appears to confer an elevated risk of OSA despite lower rates of obesity. Among African Americans, Native Americans, and Hispanics, OSA prevalence is increased, likely due in part to obesity. The burden of symptoms, particularly excessive daytime sleepiness, is higher among African Americans, although Hispanics more often report snoring. Limited data suggest that African Americans may be more susceptible to hypertension in the setting of OSA. While differences in genetic risk factors may explain disparities in OSA burden, no definitive genetic differences have yet been identified. In addition to disparities in OSA development, disparities in OSA diagnosis and treatment have also been identified. Increased severity of disease at diagnosis among African Americans suggests a delay in diagnosis. Treatment outcomes are also suboptimal among African Americans. In children, tonsillectomy is less likely to cure OSA and more commonly associated with complications in this group. Among adults, adherence to continuous positive airway pressure (CPAP) is substantially lower in African Americans. The reasons for these disparities, particularly in outcomes, are not well understood and should be a research priority.

White coat hypertension and obstructive sleep apnea

PURPOSE

This study aimed to determine blood pressure characteristics and long-term progress in patients with white coat hypertension (WCH) and obstructive sleep apnea (OSA).

METHODS

Systolic blood pressure (SBP) and diastolic blood pressure (DBP) and sleep test results over a period of 26 months were analyzed from WCH patients with OSA (n = 28), WCH patients (n = 23), and healthy control subjects (n = 27).

RESULTS

At the end of observation, WCH patients with OSA presented significantly increased daytime and nighttime BP and lower diurnal difference of SBP (all Ps < 0.05) and the increased rate of "non-dipper" status (SBP 28.6 %, DBP 32.1 %) was significantly higher when compared with WCH and control groups (all Ps < 0.01). Sustained hypertension was observed in 42.8 % of the WCH patients with OSA, which was significantly higher than that in the WCH and control groups (Ps < 0.01) and was predicted by non-dipper status via 24-h ambulatory SBP/DBP monitoring (Ps < 0.05).

CONCLUSION

WCH may represent a prehypertension status, which could develop into sustained hypertension with OSA.

Role of the sympathetic nervous system in hypertension and hypertension-related cardiovascular disease

A number of cardiovascular disease have been shown to be characterized by a marked increase in sympathetic drive to the heart and the peripheral circulation. This is the case for essential hypertension, congestive heart failure, cardiac arrhythmias, obesity, metabolic syndrome, obstructive sleep apnea, and chronic renal disease. This review focuses on the most recent findings documenting the role of sympathetic neural factors in the development and progression of the hypertensive state as well as in the pathogenesis of hypertension-related target organ damage. It also reviews the role of sympathetic neural factors in the development of cardiovascular diseases not necessarily strictly related to the hypertensive state, such as congestive heart failure, cardiac arrhythmias, obesity, metabolic syndrome and renal failure. The paper will finally review the pharmacological and non-pharmacological interventions acting on the sympathetic drive. Emphasis will be given to the new approaches, such as renal nerves ablation and carotid baroreceptor stimulation, which have been shown to exert sympathoinhibitory effects.

Correlates of isolated nocturnal hypertension and target organ damage in a population-based cohort of African Americans: the Jackson Heart Study

BACKGROUND

African Americans have higher rates of nocturnal hypertension and less nocturnal blood pressure (BP) dipping compared with whites. Although nocturnal hypertension is associated with increased cardiovascular morbidity and mortality, its clinical significance among those with normal daytime BP is unclear. This paper reports the prevalence and correlates of isolated nocturnal hypertension (INH) in a population-based cohort of African Americans enrolled in the Jackson Heart Study (JHS).

METHODS

The study sample included 425 untreated, normotensive and hypertensive JHS participants who underwent 24-hour ambulatory BP monitoring (ABPM), echocardiography, and 24-hour urine collection. Multiple logistic regression and 1-way analysis of variance models were used to test the hypothesis that those with INH have worse target organ damage reflected by greater left ventricular (LV) mass and proteinuria compared with normotensive participants.

RESULTS

Based on 24-hour ABP profiles, 19.1% of participants had INH. In age and sex-adjusted models, participants with INH had greater LV mass compared with those who were normotensive (P = 0.02), as well as about 3 times the odds of LV hypertrophy and proteinuria (Ps < 0.10). However, multivariable adjustment reduced the magnitude and statistical significance of each of these differences.

CONCLUSIONS

INH was associated with increased LV mass compared with normo tension in a population-based cohort of African Americans enrolled in the JHS. There were trends toward a greater likelihood of LV hyper trophy and proteinuria among participants with INH vs. those who were normotensive. The clinical significance of the noted target organ damage should be explored in this population.

Predictors of slow-wave sleep in a clinic-based sample

Slow-wave sleep has been associated with several physiological phenomena, including glucose metabolism, sympathetic nervous system activity, hormonal secretion and blood pressure regulation. The aim of these analyses was to determine which sociodemographic and medical factors were associated with slow-wave sleep duration in a large clinical sample. We conducted cross-sectional analysis of clinical data from 1019 consecutive adults over a 10-month period who had their first in-laboratory polysomnogram for suspicion of obstructive sleep apnea. Patients either underwent in-laboratory full-night polysomnogram followed by full-night continuous positive airway pressure titration or split-night polysomnogram. Patients also completed questionnaires to assess race, education, marital status and medical co-morbidities. A multiple linear regression model that predicted the natural log of slow-wave sleep in minutes indicated that African Americans had approximately 48% less slow-wave sleep than non-African Americans. Increasing age and male gender were also associated with less slow-wave sleep. Overweight and obese individuals had significantly less slow-wave sleep than those not overweight, even after adjustment for obstructive sleep apnea severity. Finally, those with severe obstructive sleep apnea had significantly less slow-wave sleep than those with less severe obstructive sleep apnea even after adjustment for obesity. Results remained unchanged when patients who had a split-night polysomnogram were excluded. We observed less slow-wave sleep in African Americans, a group at increased risk of diabetes and hypertension compared with Caucasians, and in those who are overweight and obese and those with severe obstructive sleep apnea. Future research needs to explore potential reasons for reduced slow-wave sleep in these individuals.

Sleep disorders and stroke

The purpose of this review is to highlight existing literature on the epidemiology, pathophysiology, and treatments of stroke sleep disorders. Stroke sleep disorders are associated with many intermediary vascular risk factors leading to stroke, but they may also influence these risk factors through direct or indirect mechanisms. Sleep disturbances may be further exacerbated by stroke or caused by stroke. Unrecognized and untreated sleep disorders may influence rehabilitation efforts and poor functional outcomes following stroke and increase risk for stroke recurrence. Increasing awareness and improving screening for sleep disorders is paramount in the primary and secondary prevention of stroke and in improving stroke outcomes. Many vital questions about the relationship of sleep disorders and stroke are still unanswered and await future well-designed studies.

The effect of zolpidem on sleep quality, stress status, and nondipping hypertension

OBJECTIVE

Poor sleep quality and stress status have previously been shown to be closely associated with higher activation of the sympathetic nervous system and to be independent predictors of nondipping hypertension. This study aimed to evaluate the effects of the non-hypotensive sedative zolpidem on sleep quality, stress status, and nondipping hypertension.

METHODS

A total of 103 nondippers were defined as poor or good sleepers by the Pittsburgh Sleep Quality Index. They were randomized to receive zolpidem or placebo treatment for 30 days. Stress status was assessed by the Perceived Stress Scale, and levels of epinephrine and norepinephrine were examined to investigate the underlying mechanisms.

RESULTS

Poor sleepers treated with zolpidem for 30 days showed significant improvements in sleep quality and stress levels (P<0.01). More nondippers were converted to dippers in the group of poor sleepers treated with zolpidem (11 of 22 patients, 50.0%) than in the placebo (2 of 23, 8.7%) (P<0.01). Epinephrine and norepinephrine levels were significantly reduced in poor sleepers treated with zolpidem (P<0.05).

CONCLUSION

The results of this study suggest that zolpidem can improve sleep quality and stress status, and can convert nondippers with poor sleep quality into dippers. It may be an option for treating nondipping hypertensive patients with poor sleep quality.

Snoring and insomnia are not associated with subclinical atherosclerosis in the Northern Manhattan Study

BACKGROUND

Sleep-disordered breathing is a risk factor for stroke, but its association with subclinical atherosclerosis remains controversial. Snoring and insomnia are frequently comorbid with sleep-disordered breathing and may contribute to stroke. Data on the relationship between snoring and insomnia with atherosclerotic disease are sparse. We investigated the relationship between markers of subclinical atherosclerosis, insomnia, snoring, and carotid intima-media thickness, in the Northern Manhattan Study.

METHODS

A group of 1605 participants (mean age 65 +/- 8 years; 40% men; 61% Hispanic, 19% black, 20% white) who had carotid intima-media thickness measurements performed was assessed for self-reported sleep habits. Habitual snoring was defined as self-reported snoring greater than four times per week. Presence of insomnia was based on three items extracted from the Hamilton Rating Scale for Depression. Carotid intima-media thickness was expressed as a mean composite measure of intima-media thickness in the carotid bifurcation, common, and internal carotid artery. Multivariate linear regression models were used to identify associations between snoring, insomnia, and carotid intima-media thickness.

RESULTS

Habitual snoring was present in 29% of the subjects and insomnia in 26%. There was a higher prevalence of self-reported snoring (84%) and insomnia (66%) among Hispanics than non-Hispanics. The mean total carotid intima-media thickness was 0.95 +/- 0.09 mm; among those with self-reported snoring was 0.94 +/- 0.09 mm; and among those with insomnia was 0.95 +/- 0.08 mm. After controlling for age, gender, race-ethnicity, body mass index and cardiovascular risk factors, snoring (P=0.986) and insomnia (P=0.829) were not significantly associated with increased carotid intima-media thickness.

CONCLUSION

Snoring and insomnia were not significantly associated with subclinical atherosclerosis in this population-based community cohort.

Perspective on sleep and aging

There is a strong body of data directly interrelating sleep problems with mood disorders. There is a growing data base directly associating sleep disorders with attention and memory problems. Motor disorders, especially involving the dopaminergic system, may produce sleep problems, including a possible association between disordered sleep and nocturnal falls. Sleep disorders may be causal conditions for metabolic diseases and increased risk for morbidity and mortality. Sleep and health are directly interrelated. To further probe these issues, especially as related to the aging process, investigators need to utilize tools and concepts from genomics and epigenetics, proteomics, metabolomics, any future …omics, molecular neuroimaging, and cognitive neuroscience.

Cardiovascular consequences of sleep apnea

Cardiovascular disease has been the leading cause of death since 1900. Strategies for cardiovascular disease and prevention have helped to reduce the burden of disease, but it remains an important public health challenge. Therefore, understanding the underlying pathophysiology and developing novel therapeutic approaches for cardiovascular disease is of crucial importance. Recognizing the link between sleep and cardiovascular disease may represent one such novel approach. Obstructive sleep apnea (OSA), a common form of sleep-disordered breathing, has a high and rising prevalence in the general adult population, attributable in part to the emerging epidemic of obesity and enhanced awareness. OSA has been independently linked to specific cardiovascular outcomes such as hypertension, stroke, myocardial ischemia, arrhythmias, fatal and nonfatal cardiovascular events, and all-cause mortality. Treatment of OSA may represent a novel target to reduce cardiovascular health outcomes.

Sleep health in U.S. Hispanic population

The importance of sleep on health has only been recently recognized, and the general public and the medical community are not yet fully knowledgeable about this issue. The great majority of sleep research has been performed in whites of European descent and to a lesser extent in African Americans, making generalization of the findings to other ethnic and racial groups difficult. Very little sleep research has been done in U.S. Hispanics. However, based on the available literature and the high prevalence of risk factors in Hispanics, such as obesity, diabetes, living in the inner city, and use of alcohol, the prevalence of such important sleep disorders such as obstructive sleep apnea and sleep habits such as poor sleep hygiene are suspected to be high. There is also some evidence that acculturation to the U.S. life style may lead to worse sleep habits in Hispanics, including fewer hours of sleep. Two current large NIH sponsored studies of sleep in U.S. Hispanics promise to significantly add to the literature on various sleep disorders such as sleep disordered breathing, insomnia, restless legs syndrome, periodic limb movement disorder, and sleep habits such as short sleep duration and sleep hygiene.

The price of obstructive sleep apnea-hypopnea: hypertension and other ill effects

This review addresses the cardiovascular, cerebrovascular, and metabolic consequences that accompany obstructive sleep apnea-hypopnea (OSAH) in conjunction with the mechanistic pathways implicated in mediating these effects. Particular emphasis is placed on the association with hypertension (HTN). Varying levels of evidence support a role of OSAH in perpetuating sustained HTN, nocturnal HTN, and difficult to control HTN as well as in contributing to the occurrences of nondipping of blood pressure (BP) and increased BP variability. In this context, the emergence of matched designs, adjusted analyses, meta-analyses as well as longitudinal and interventional studies strengthens causal inferences drawn from older observational studies, which suffered from such limitations as confounding.

Sleep-disordered breathing and 24-hour blood pressure pattern among older adults

BACKGROUND

To examine the association between sleep-disordered breathing (SDB) and 24-hour blood pressure (BP) pattern among community-dwelling older adults.

METHODS

A convenience sample of 70 community-dwelling older adults, recruited from senior housing, community centers, and learning centers, were admitted to General Clinical Research Center, Emory University Hospital, Atlanta, Ga. Information regarding demographic and clinical history was obtained using questionnaires. Twenty-four-hour BP monitoring in supine position was performed using Spacelabs model 20207. Breathing during sleep was monitored with the use of a modified sleep recording system (Embletta, PDS), which monitors nasal and oral airflow, chest and abdominal movements, and pulse oximetry. Night time-daytime (night-day) BP ratio (average night-time BP divided by daytime BP) was calculated both for systolic and diastolic BPs.

RESULTS

Sixty-nine participants, mean age 74.9 +/- 6.4 years (41 [57%] women), completed the study. The mean apnea-hypopnea index (AHI) was 13 +/- 13 per hour of sleep, and 20 participants (29%) had AHI > or =15 per hour of sleep, indicating moderate to severe SDB. Moderate to severe SDB (AHI > or =15 per hour of sleep) was significantly associated with nocturnal hypertension, whereas there was no statistically significant difference in wake-time BP between those with and without moderate to severe SDB. Stepwise multiple regressions showed that AHI independently predicted increased night-day systolic and night-day diastolic BP ratio, even after controlling for nocturia frequency.

CONCLUSIONS

The results indicate increased BP load associated with increased AHI in this group of older adults. This increased BP load may contribute to increased hypertension-related morbidity and disease burden.

Longitudinal association of sleep-disordered breathing and nondipping of nocturnal blood pressure in the Wisconsin Sleep Cohort Study

STUDY OBJECTIVES

The association of sleep-disordered breathing (SDB) and blunting of normal nocturnal lowering of blood pressure (BP) (nondipping) has only been examined cross-sectionally. The purpose of this study is to investigate whether SDB is prospectively associated with nondipping.

METHODS

The longitudinal association between SDB and incident nondipping was examined in a subsample of 328 adults enrolled in the Wisconsin Sleep Cohort Study who completed 2 or more 24-hour ambulatory BP studies over an average of 7.2 years of follow-up. SDB identified by baseline in-laboratory polysomnography was defined by apnea-hypopnea index (AHI) categories. Systolic and diastolic nondipping was defined by systolic and diastolic sleep-wake BP ratios > 0.9. All models were adjusted for age, sex, body mass index at baseline and follow-up, smoking, alcohol consumption, hypertension, sleep time, length of follow-up time, and antihypertensive medication use.

RESULTS

There was a dose-response increased odds of developing systolic nondipping in participants with SDB. The adjusted odds ratios (95% confidence interval) of incident systolic nondipping for baseline AHI 5 to < 15 and AHI > or = 15, versus AHI < 5, were 3.1 (1.3-7.7) and 4.4 (1.2-16.3), respectively (P trend = 0.006). The adjusted odds ratios (95% confidence interval) of incident diastolic nondipping for corresponding SDB categories were not statistically significant: 2.0 (0.8-5.6) and 1.3 (0.2-7.1).

CONCLUSIONS

Our longitudinal findings of a dose-response increase in development of systolic nondipping of BP with severity of SDB at baseline in a population-based sample provide evidence consistent with a causal link. Nocturnal systolic nondipping may be a mechanism by which SDB contributes to increased cardiovascular disease.

Sleep-disordered breathing and cardiovascular disease in the Bay Area Sleep Cohort

STUDY OBJECTIVES

To examine the relationship between sleep-disordered breathing (SDB) and cardiovascular disease among community-dwelling older adults. Previous studies have suggested relatively stronger associations between SDB and such morbidity in middle-aged, relative to elderly, populations.

DESIGN

Cross-sectional analysis of an elderly ambulatory, non-clinic-based cohort (Bay Area Sleep Cohort, BASC) SETTING: Community population studied in a sleep laboratory

PARTICIPANTS

One hundred twenty-nine older adults (mean [+/- SD] age = 72.6 [8.3]) (78 women; 51 men).

INTERVENTIONS

NA.

MEASUREMENTS

Complete clinical history including list of current medications, physical examination, selected blood chemistries, multiple blood pressure measurements, 12-lead electrocardiogram, and 2 consecutive nights of polysomnography.

RESULTS

Fifty-one individuals (40%) were taking 1 or more cardiovascular medications and 24 (19%) had an apnea-hypopnea index (AHI) of 10 or more per hour of sleep. Cardiovascular medication use was related to cardiac events or procedures, history of angina, higher systolic or diastolic blood pressure, and abnormal electrocardiogram. Logistic regression showed statistically significant association between cardiovascular medication use and AHI of 10 or greater per hour, independent of age, sex, and body mass index. Supplementary analyses indicated that rapid eye movement AHI of 10 or greater per hour was significantly associated with elevated diastolic blood pressure.

CONCLUSIONS

The results suggest that sleep-disordered breathing may contribute to increased cardiovascular morbidity in older adults.

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.

Obesity, ethnicity, and sleep-disordered breathing: medical and health policy implications

The obesity epidemic in the United States is a major health problem, which poses im-mediate and long-term health risks with potential for significant reduction in life expectancy if not curtailed. Despite affecting all segments of the population, minorities carry a relatively larger burden of the obesity threat. Obesity is a major risk factor for develop-ing obstructive sleep apnea and the metabolic syndrome, which are associated with increased cardiovascular and cerebrovascular morbidity and mortality. This article discusses the implications of the obesity trend on the prevalence of obstructive sleep ap-nea and health, highlights ethnic differences, reviews the resultant economic implications, and suggests public health and health policy initiatives that may be beneficial in stemming the obesity scourge.

The sleep of African Americans: a comparative review

Researchers have not thoroughly assessed the sleep of African Americans (AAs) despite the recent increased attention to ethnic research. This article reviews the sleep and epidemiological literatures to assess AA sleep. Although the limited data were sometimes inconsistent, they suggest that AAs sleep worse than Caucasian Americans. AAs take longer to fall asleep, report poorer sleep quality, have more light and less deep sleep, and nap more often and longer. AAs have a higher prevalence of sleep-disordered breathing and exhibit more risk factors for poor sleep. These differences are concentrated in young- and middle-age adults. There are no sleep disorders treatment data for AAs. These data support further research into ethnic differences in both normal and disturbed sleep.

Nondipping blood pressure patterns among individuals with essential hypertension: a review of the literature

BACKGROUND

Researchers have discovered that blood pressure (BP) varies in a diurnal manner throughout a 24-hour period, being higher during the day and lower at night. Most people have a dipping BP pattern characterized by a nighttime BP that is 10-20% lower than their daytime BP. Individuals who experience a less than 10% reduction in nighttime BP are described as having a nondipping BP pattern. Although controversial, there is a growing body of evidence suggesting that a nondipping BP pattern is associated with a greater risk of target organ damage among individuals with essential hypertension.

AIM

To review the literature on the most common factors associated with nondipping BP patterns among individuals with essential hypertension.

METHODS

CINAHL (1982-March 2006), PubMed (1950-March 2006) and Cochrane Library (1966-March 2006) databases were searched using the keywords: dipper, dipping, nondipper, nondipping, ambulatory blood pressure monitoring, ABPM, hypertension, essential hypertension, high blood pressure, blood pressure, nocturnal blood pressure, nighttime blood pressure, diurnal blood pressure, and blood pressure patterns. Published studies, abstracts, dissertations as well as the reference lists of retrieved articles were reviewed. Studies were included if they involved subjects with only treated or untreated essential hypertension or those with samples of both nomotensive and treated or untreated essential hypertensive individuals. Additionally, studies needed to evaluate 24-hour, daytime and nighttime BP patterns.

RESULTS

There is some evidence to suggest advanced age, African-American ethnicity, female sex, postmenopausal status, sodium sensitivity, sleep apnea, sleep quality, anger, hostility, depression, stress, social support, and socioeconomic status have an association with nondipping BP patterns.

CONCLUSION

Knowledge of the potential factors associated with an altered nighttime BP pattern is of importance because it can help identify persons at risk for nondipping BP patterns and potential target organ damage. Furthermore, knowledge of these factors associated with a nondipping BP profile will lay the foundation for interventions to prevent/treat alterations in nighttime BP patterns.

Sleep-Disordered Breathing in Patients With Difficult-to-Control Hypertension

OBJECTIVE

To analyze the relationship between sleep-disordered breathing and difficult-to-control arterial hyper-tension.

PATIENTS AND METHODS

Patients were considered to have difficult-to-control hypertension when mean systolic blood pressure was 125 mm Hg or higher and/or mean diastolic blood pressure was more than or equal to 80 mm Hg (as recorded during 2 24-hour ambulatory monitoring studies) despite the use of 3 or more antihypertensive drugs. Respiratory polygraphy using the AutoSet device (ResMed Corp, Sydney, Australia) was then performed to study sleep-disordered breathing in all patients.

RESULTS

Forty-nine patients with a mean (SD) age of 68.1 (9.1) years, mean systolic and diastolic pressures of 152.5 (13)/89.2 (8.5) mm Hg, and an average of 3.5 prescribed drugs were included in the study. The mean apnea-hypopnea index (AHI) was 26.2 (19.5) and events were predominantly obstructive. Patients with severe sleep apnea-hypopnea syndrome (SAHS) (AHI > or = 30; 40.8%) showed more uncontrolled daytime (P = .017) and nighttime (P = .033) systolic pressure than the rest, as well as higher daytime diastolic pressure (P = .035) and a greater consumption of drugs than those without severe SAHS (AHI < 10; 28.6%) (P = .041). The study population as a whole showed a significant correlation between blood pressure and obesity. There was a significant correlation (adjusted for age and sex) with AHI only in patients with SAHS. AHI was found to be the independent predictor with the greatest effect on blood pressure in these patients.

CONCLUSIONS

Prevalence of SAHS was very high in patients with difficult-to-control hypertension. In patients with SAHS, AHI was found to be the independent predictor with the greatest affect on arterial blood pressure.

The association between interleukin-6, sleep, and demographic characteristics

We examined the relationship between the pro-inflammatory cytokine IL-6 and sleep architecture in 70 healthy men and women. Blood was drawn in the early morning for assessment of IL-6 followed by nocturnal sleep monitoring with polysomnography. Sleep records were scored for sleep stages using standard criteria. Morning IL-6 levels were positively correlated with REM latency after sleep onset [rho = .31, p = .01], percent (%) stage 1 sleep [rho = .23, p = .053], % wake after sleep onset (WASO) [rho = .29, p<.05]. IL-6 levels were negatively correlated with sleep efficiency [rho = -.36, p<.01] and slow wave sleep (SWS) [rho = -.26, p<.05]. After controlling for demographic variables including race, gender, age, and BMI, multiple hierarchical regression analyses revealed that morning IL-6 levels accounted for a significant portion of the variance of REM latency (p<.01), sleep efficiency (p<.01), and % WASO (p = .01). IL-6 was no longer associated with % stage 1 sleep, SWS, and total sleep time after controlling for the demographic characteristics. These findings suggest that the inflammatory marker IL-6 is associated with sleep quality and that certain individual characteristics such as race, gender, and age modify that relationship. Higher IL-6 levels were associated with lower quality of sleep among healthy asymptomatic men and women.

Socioeconomic status is associated with nocturnal blood pressure dipping

OBJECTIVE

With the advent of ambulatory blood pressure monitoring has come the awareness that blood pressure (BP) normally drops, or "dips," at night by roughly 10%. A number of pathological conditions have been associated with the nondipping of nocturnal BP. In general, researchers have looked at dipping in neurological and cardiovascular disorders. We examined the extent to which nocturnal nondipping might be influenced by relatively gross measures of social environment.

METHODS

This study examined 78 healthy adults and adults with mild hypertension who were not currently receiving medication, aged 25 to 52 years (mean age = 38.2). Forty-two participants self-identified as black and 36 identified as white.

RESULTS

Age, body mass index, apnea-hypopnea index, screening BP, ethnicity, and socioeconomic status (SES) were significantly associated with nocturnal BP dipping, accounting for 41% of the variance in dipping (F[6,51] = 5.473, p <.001). When SES was entered on the last step of a hierarchical regression analysis, it independently accounted for 8% of the variance in dipping, even after accounting for ethnicity, such that the lower the SES, the more the nondipping.

CONCLUSION

It remains to be seen what aspect of the social environment may be driving this association between nondipping and lower social class. However, investigators might consider including social class in their models in future studies.

Efficacy of positive airway pressure and oral appliance in mild to moderate obstructive sleep apnea

The efficacy of currently recommended treatments is uncertain in patients with mild to moderate obstructive sleep apnea (apnea-hypopnea index [AHI], 5-30). A group of 114 sleep clinic patients with an AHI of 5-30 have participated in a randomized controlled crossover trial of 3 months of treatment with each of nasal continuous positive airway pressure (CPAP), a mandibular advancement splint, and a placebo tablet. Outcomes were sleep fragmentation and hypoxemia, daytime sleepiness, quality of life, neurobehavioral function, and blood pressure. Both active treatments improved sleep outcomes, but positive airway pressure had a greater effect. The quality of life, symptoms, and subjective but not objective sleepiness improved to a similar degree with both treatments; however, many of the improvements seen in neuropsychologic function and mood were not better than the placebo effect. Some aspects of nocturnal blood pressure were improved with the splint but not with CPAP. This study has shown that although both CPAP and mandibular advancement splint effectively treated sleep-disordered breathing and sleepiness, the expected response in neurobehavioral function was incomplete. This may be due to the splint having a lesser therapeutic effect and CPAP being poorly tolerated and therefore used less in this patient group.