All-cause mortality in males with sleep apnoea syndrome: declining mortality rates with age

Uvulopalatopharyngoplasty reduces the incidence of cardiovascular complications caused by obstructive sleep apnea: results from the national insurance service survey 2007-2014

OBJECTIVE

Untreated obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease including myocardial infarction (MI), congestive heart failure (CHF), and atrial fibrillation (AF). Continuous positive airway pressure (CPAP) is an effective treatment for OSA; however, compliance with CPAP can be challenging for some patients. The objective of this study was to investigate whether uvulopalatopharyngoplasty (UPPP) reduced the risk of cardiovascular complications for patients with OSA.

METHODS

Data from Korea National Health Insurance Corporation, a national health care database in South Korea, were analyzed. All patients with a new diagnosis of OSA from 2007 to 2014 were identified. Propensity score matching by age and sex was used to identify a control group five times larger than the OSA group for comparison. Patient demographics and comorbidities were collected. The OSA group was further divided into patients who had an UPPP and patients who did not undergo surgery. The primary endpoints were newly diagnosed MI, CHF, and AF.

RESULTS

Of 192,316 patients with a new diagnosis of OSA, 22,213 had undergone UPPP. For the control group, 961,590 individuals were selected. Patients with OSA had an increased risk of CHF and AF, compared to control patients. UPPP reduced the incidence of CHF and AF significantly. Age, gender, and hypertension were also found to be risk factors for cardiac complications for patients with OSA.

CONCLUSION

OSA increases the risk of CHF and AF. UPPP in this population can significantly reduce the risk of cardiac complications in patients with OSA.

Obstructive sleep apnoea-hypopnoea and arrhythmias: new updates

AIMS

Obstructive sleep apnoea-hypopnoea (OSAH) is a prevalent condition characterized by repetitive pharyngeal collapse during sleep, leading to hypoxemia, hypercapnia, and persistent inspiratory efforts against an occluded airway until arousal. Several studies demonstrated that OSAH exerts acute and chronic effects on the cardiovascular system. Thus, although being a respiratory problem, the most important consequences of OSAH are cardiovascular, among which there are arrhythmias. The purpose of this review is to systematically analyse what has been recently published about the relationship between OSAH and every cardiac arrhythmia separately.

METHODS

We searched Pubmed, Scopus, Web of Science and Cochrane Collaboration databases for 'OSAHS arrhythmias', 'OSAH arrhythmias' and 'OSA arrhythmias'. We analyse 1298 articles and meta-analyses, excluding already edited reviews.

RESULTS

Arrhythmias, especially of ventricular origin, are frequent in OSAH. Ventricular premature beats, couplets and ventricular tachycardia runs are even more frequent in patients suffering from heart failure. They may be due to left heart remodelling, overwork and ischaemia and can explain at least some sudden deaths occurring between midnight and 6 a.m. Sinus pauses and atrioventricular blocks are increased according to the severity of the disturbance and may be reduced by continuous positive airway pressure therapy, preventing pace-maker implantation. Finally, atrial fibrillation, resistance against antiarrhythmic drugs and recurrences after surgical procedures are strongly related to OSAH.

CONCLUSION

Arrhythmias are frequent in OSAH. Treatment of OSAH may reduce some of them. An implantable cardioverter-defibrillator and continuous positive airway pressure should be considered in some patients.

Impact of age on intermittent hypoxia in obstructive sleep apnea: a propensity-matched analysis

PURPOSE

To determine independent relationship of aging with chronic intermittent hypoxia, we compared hypoxia-related polysomnographic variables of geriatric patients (aged ≥ 65 years) with an apnea-hypopnea index (AHI)-, gender-, body mass index (BMI)-, and neck circumference-matched cohort of non-geriatric patients.

METHODS

The study was conducted using clinical and polysomnographic data of 1280 consecutive patients who underwent complete polysomnographic evaluation for suspected sleep-disordered breathing (SDB) at a single sleep disorder center. A propensity score-matched analysis was performed to obtain matched cohorts of geriatric and non-geriatric patients, which resulted in successful matching of 168 patients from each group.

RESULTS

Study groups were comparable for gender (P = 0.999), BMI (P = 0.940), neck circumference (P = 0.969), AHI (P = 0.935), and severity of SDB (P = 0.089). The oximetric variables representing the duration of chronic intermittent hypoxia such as mean (P = 0.001), the longest (P = 0.001) and total apnea durations (P = 0.003), mean (P = 0.001) and the longest hypopnea durations (P = 0.001), and total sleep time with oxygen saturation below 90% (P = 0.008) were significantly higher in the geriatric patients as compared with younger adults. Geriatric patients had significantly lower minimum (P = 0.013) and mean oxygen saturation (P = 0.001) than non-geriatric patients.

CONCLUSIONS

The study provides evidence that elderly patients exhibit more severe and deeper nocturnal intermittent hypoxia than the younger adults, independent of severity of obstructive sleep apnea, BMI, gender, and neck circumference. Hypoxia-related polysomnographic variables in geriatric patients may in fact reflect a physiological aging process rather than the severity of a SDB.

Prevalence and predictors of sleep apnea in patients with stable coronary artery disease: a cross-sectional study

BACKGROUND

Sleep apnea (SA) is increasingly recognized as being important in the prognosis of patients with coronary artery disease (CAD); however, symptoms of SA are not easily identified, and as many as 80% of sufferers remain undiagnosed.

AIM

This cross-sectional study investigated the prevalence and predictors of SA that may help to increase the awareness and diagnosis of SA in stable CAD patients.

MATERIALS AND METHODS

Polysomnography was performed in 772 medically stable CAD patients with untreated SA recruited from the Clinic of Cardiovascular Rehabilitation. Patients were predominantly male (76%), median age was 58 years (32-81). All subjects completed the Epworth sleepiness scale (ESS). The frequency of all apneas and hypopneas associated with 3% oxygen desaturation is referred to as the apnea-hypopnea index (AHI). Mild-to-severe SA was defined as AHI ≥5/h, moderate-to-severe SA as AHI ≥15/h.

RESULTS

AHI was within a range of values that was considered normal or only mildly elevated. The median AHI was 3.4 (interquartile range [IQR 1-9]), and 39% of patients had unrecognized mild-to-severe SA (moderate-to-severe in 14%), which was not higher than other known risk indicators for CAD such as hypertension and obesity (83% and 47%, respectively). These patients did not show sleepiness and the risk-related cut-off score for excessive daily sleepiness was lower than the official for ESS.

CONCLUSION

Hypertension, age, male gender, obesity, ESS ≥6, and left ventricular ejection fraction ≤45% were the best predictors of mild-to-severe SA. While, male gender, age 50-70 years and, mainly, the presence of obesity but not hypertension were clinical predictors for moderate-to-severe SA. In addition, association between mild-to-severe SA and obesity was not evident in women. SA is prevalent comorbidity in the stable CAD patients, especially in its asymptomatic mild form. We suggest that SA should be considered in the secondary prevention protocols for CAD.

Reviewing the relationship between OSA and cognition: Where do we go from here?

Obstructive sleep apnoea (OSA) is a disorder of breathing during sleep resulting in temporary reduction in cerebral oxygenation and sleep disruption. A growing body of research reveals a relatively consistent pattern of deficits in cognition, particularly in attention, episodic memory, and executive function, which are partially remediated by treatment. This is where the consensus ends. Despite a number of competing explanations regarding how OSA affects cognition, reliable evidence is hard to find, which may relate to the many, common conditions co-morbid with OSA or to the methodological challenges in this field. This paper reviews the evidence for cognitive impairment in OSA, the proposed models of cognitive harm, the impact of co-morbidities and the many methodological and theoretical challenges of exploring the effect of OSA on cognition. To overcome some of these challenges, we end by proposing a number of future directions for the field, including suggesting some core design elements for future studies.

Cardiac Troponin Values in Patients With Acute Coronary Syndrome and Sleep Apnea: A Pilot Study

BACKGROUND

An analysis of cardiac injury markers in patients with OSA who sustain an episode of acute coronary syndrome (ACS) may contribute to a better understanding of the interactions and impact of OSA in subjects with ACS. We compared peak cardiac troponin I (cTnI) levels in patients with OSA and patients without OSA who were admitted for ACS.

METHODS

Blood samples were collected every 6 hours from the time of admission until two consecutive assays showed a downward trend in the cTnI assay. The highest value obtained defined the peak cTnI value, which provides an estimate of infarct size.

RESULTS

We included 89 patients with OSA and 38 patients without OSA with an apnea-hypopnea index of a median of 32 (interquartile range [IQR], 20.8-46.6/h and 4.8 [IQR, 1.6-9.6]/h, respectively. The peak cTnI value was significantly higher in patients without OSA than in patients with OSA (median, 10.7 ng/mL [IQR, 1.78-40.1 ng/mL] vs 3.79 ng/mL [IQR, 0.37-24.3 ng/mL]; P = .04). The multivariable linear regression analysis of the relationship between peak cTnI value and patient group, age, sex, and type of ACS showed that the presence or absence of OSA significantly contributed to the peak cTnI level, which was 54% lower in patients with OSA than in those without OSA.

CONCLUSIONS

The results of this study suggest that OSA has a protective effect in the context of myocardial infarction and that patients with OSA may experience less severe myocardial injury. The possible role of OSA in cardioprotection should be explored in future studies.

Impact of obstructive sleep apnoea and intermittent hypoxia on cardiovascular and cerebrovascular regulation

NEW FINDINGS

What is the topic of this review? This review examines the notion that obstructive sleep apnoea (OSA) and intermittent hypoxia (IH) have hormetic effects on vascular health. What advances does it highlight? Clinical (OSA patient) and experimental animal and human models report that IH is detrimental to vascular regulation. However, mild IH and, by extension, mild OSA also have physiological and clinical benefits. This review highlights clinical and experimental animal and human data linking OSA and IH to vascular disease and discusses how hormetic effects of OSA and IH relate to OSA severity, IH intensity and duration, and patient/subject age. Obstructive sleep apnoea (OSA) is associated with increased risk of cardiovascular and cerebrovascular disease, a consequence attributed in part to chronic intermittent hypoxia (IH) resulting from repetitive apnoeas during sleep. Although findings from experimental animal, and human, models have shown that IH is detrimental to vascular regulation, the severity of IH used in many of these animal studies [e.g. inspired fraction of oxygen (FI,O2) = 2-3%; oxygen desaturation index = 120 events h^-1 ] is considerably greater than that observed in the majority of patients with OSA. This may also explain disparities between animal and recently developed human models of IH, where IH severity is, by necessity, less severe (e.g. FI,O2 = 10-12%; oxygen desaturation index = 15-30 events h^-1 ). In this review, we highlight the current knowledge regarding the impact of OSA and IH on cardiovascular and cerebrovascular regulation. In addition, we critically discuss the recent notion that OSA and IH may have hormetic effects on vascular health depending on conditions such as OSA severity, IH intensity and duration, and age. In general, data support an independent causal link between OSA and vascular disease, particularly for patients with severe OSA. However, the data are equivocal for older OSA patients and patients with mild OSA, because advanced age and short-duration, low-intensity IH have been reported to provide a degree of protection against IH and ischaemic events such as myocardial infarction and stroke, respectively. Overall, additional studies are needed to investigate the beneficial/detrimental effects of mild OSA on the various vascular beds.

Association between Obstructive Sleep Apnea and Myocardial Infarction: A Systematic Review

Obstructive sleep apnea (OSA) has been associated to cardiovascular risk factors. However, the association between OSA and cardiovascular disease is still controversial. The objective of the present study was to verify the association between OSA and myocardial infarction (MI). This is a systematic review of the literature performed through electronic data sources MEDLINE/PubMed, PubMed Central, Web of Science and BVS -Biblioteca Virtual em Saúde (Virtual Health Library). The descriptors used were: 'obstructive sleep apnea' AND 'polysomnography' AND 'myocardial infarction' AND 'adults NOT 'treatment.' The present work analysed three prospective studies, selected from 142 articles. The studies followed a total sample of 5,067 OSA patients, mostly composed by male participants. All patients underwent night polysomnography, and all studies found an association between OSA and fatal and non-fatal cardiovascular outcomes. Thus, we were able to observe that 644 (12.7%) of the 5,067 patients suffered MI or stroke, or required a revascularization procedure, and 25.6% of these cardiovascular events were fatal. MI was responsible for 29.5% of all 644 analysed outcomes. There is an association between OSA and MI, in male patients, and apnea and hypopnea index (AHI) are the most reliable markers.

A 7-year follow-up study of obstructive sleep apnoea in healthy elderly: The PROOF cohort study

BACKGROUND AND OBJECTIVE

Clinical and epidemiological cohort studies have shown that obstructive sleep apnoea (OSA) is a common but largely undiagnosed disorder in senior subjects, where progressive deterioration of the pathology would be expected as a consequence of the ageing processes. Our study examines the longitudinal progression of OSA over a 7-year period in a community-based sample of healthy subjects.

METHODS

The sample consisted of 284 volunteers, aged >65 years (52% women, 48% men) accepting clinical and instrumental follow-up at 7 years. OSA was defined as an apnoea-hypopnoea index (AHI) of ≥15.

RESULTS

Between evaluations in the total sample, AHI slightly decreased from 17.8 ± 14 to 16.7 ± 11 with a decrease affecting more the hypopnoea index (P < 0.001) and associated with significant changes (P < 0.001) in all indices of hypoxaemia. While in the non-OSA group there was a slight but significant increase of AHI, a significant AHI decrease was noted in mild-moderate patients (P < 0.01) and a significant rise of nocturnal hypoxaemia in severe OSA patients (P < 0.001). The AHI decrease was not associated with clinical, weight, metabolic and blood pressure changes between the two evaluations; the baseline AHI value being the only factor correlated to the degree of AHI decline.

CONCLUSIONS

In elderlies, the severity and prevalence of OSA decrease progressively with ageing without effect of factors commonly influencing OSA severity. This trend may support the hypothesis that in healthy elderly, OSA is a phenomenon related to ageing.

[A clinical case of hemangioma of the face and tongue concurrent with severe obstructive sleep apnea syndrome complicated by cardiac arrhythmias and conduction disturbances]

The paper describes a clinical case of a female patient with severe obstructive sleep apnea syndrome in the presence of congenital hemangioma of the face, soft palate, and tongue concurrent with paroxysmal atrial fibrillation and atrial flutter, paroxysmal supraventricular tachycardia, and sinoatrial block (maximally up to 3.9 sec). Continuous positive airway pressure therapy could reduce the number of paroxysms of atrial fibrillation and atrial flutter, supraventricular tachycardia and eliminate sinoatrial block.

Meta-analysis of all-cause and cardiovascular mortality in obstructive sleep apnea with or without continuous positive airway pressure treatment

PURPOSE

The associations between obstructive sleep apnea (OSA) and all-cause and cardiovascular mortality are well established but are not entirely consistent. To accurately evaluate these associations as well as the therapeutic effects of continuous positive airway pressure (CPAP), we conducted a comprehensive meta-analysis of all eligible cohort studies.

METHODS

Electronic literature databases (i.e., PubMed and Embase) were searched for relevant studies published before January 2016 that evaluated the associations between OSA and all-cause or cardiovascular mortality. Random-effect models were used to calculate the pooled hazard ratio (HR) and corresponding 95 % confidence intervals (CIs) for categorical risk estimates. The therapeutic effects of CPAP treatment for all-cause and cardiovascular mortality in OSA were examined through the meta-analysis.

RESULTS

The 27 cohort studies included in the meta-analysis included 3,162,083 participants. Compared to the control group, the pooled HR of all-cause mortality was 1.19 (95 % CI, 0.86-1.65) for mild OSA, 1.28 (0.96-1.69) for moderate OSA, and 2.13 (1.68-2.68) for severe OSA. The pooled HR of cardiovascular mortality was 1.24 (0.53-2.55) for mild OSA, 2.05 (0.57-5.47) for moderate OSA, and 2.73 (1.94-3.85) for severe OSA. All-cause mortality (HR 0.66; 0.59-0.73) and cardiovascular mortality (HR 0.37; 0.16-0.54) were significantly lower in CPAP-treated than in untreated patients. There were no differences in cardiovascular mortality in CPAP-treated OSA patients vs. normal control subjects (HR 0.82; 0.52-1.29).

CONCLUSIONS

Greater attention should be paid to severe OSA, as it is an independent predictor for risk for all-cause and cardiovascular mortality. CPAP is an effective treatment that reduces risk of mortality.

Management of sleep apnea: a critical look at intra-oral appliances

With so many disciplines of both medicine and dentistry involved in the treatment of obstructive sleep apnea (OSA), several forms of therapy are available. The orthodontist is rarely considered when the diagnosis of chronic obstructive sleep apnea (OSA) is delivered. However, the scope of orthodontic care today is much broader than the mere alignment of teeth. While the current gold standard for OSA care remains continuous positive air pressure (CPAP), the patient may be given a prescription for an intra-oral sleep appliance. When orthodontists work in concert with their medical colleagues to provide a sleep appliance, several considerations must be made including the evidence regarding oral appliance efficacy. For some patients, oral appliances are highly successful; however, even for responsive patients, there are risks associated with oral appliance therapy. The aim of the paper was to present a critical review of the current level of evidence for the use of oral appliances in the treatment of OSA. A substantial number of publications ranging from case reports, uncontrolled and controlled case series, prospective randomized studies, and even a small number of systematic reviews were available. The existing systematic reviews were based on either a limited number of prospective studies with limited numbers of patients or in some cases were based on subjective data only. As a result, a narrative review of the literature was performed that discusses objective clinically testable criteria and recent developments that may aid future research investigations.

Self-Reported Sleep Disordered Breathing as Risk Factor for Mortality in the Elderly

BACKGROUND

This study aimed to examine the association between self-reported sleep disordered breathing (SDB) ("awaken short of breath or with a headache") and mortality in a large and ethnically diverse group of community-dwelling elderly people.

METHODS

A total of 1288 participants, 65 years and older, were examined longitudinally. Sleep problems were estimated using the Medical Outcomes Study Sleep Scale examining sleep disturbance, snoring, awaken short of breath or with a headache, sleep adequacy, and sleep somnolence. Cox regression analysis was used to examine the association between sleep problems and mortality. Age, gender, education, ethnicity, and body mass index were included as covariates. In further analyses we included hypertension, diabetes, heart disease, and stroke as additional covariates.

RESULTS

The participants were followed for up to 6 years (mean = 2.9, standard deviation = 1.1), and 239 (18.6%) participants died during the follow-up. In unadjusted models, SDB at the initial visit was associated with mortality (hazard ratio [HR] = 1.37; 95% confidence interval [CI] 1.21-1.55; P < .0001). After adjusting for all the covariates, the relationship between SDB and mortality remained significant (HR = 1.48; 95% CI 1.29-1.70; P < .0001). Participants with Caribbean-Hispanic ancestry have higher risk for mortality.

CONCLUSIONS

Our results suggest that SDB is a risk factor for mortality in a large and ethnically diverse group of older adults, independent of demographic and clinical factors. Further research is needed to examine the underlying mechanisms of this association.

Obstructive sleep apnoea and risks of all-cause mortality: preliminary evidence from prospective cohort studies

PURPOSE

A meta-analysis of prospective cohort studies was conducted to clarify the association between obstructive sleep apnoea (OSA) and future risk of all-cause mortality.

METHODS

Eligible studies were identified by searching the PubMed and EMBASE databases up to July 2015. Pooled hazard ratios (HRs) and their corresponding 95 % confidence intervals (CIs) were calculated to estimate the association between OSA and risk of all-cause mortality. Sources of heterogeneity were identified by subgroup and meta-regression analyses.

RESULTS

Twelve prospective cohort studies involving 34,382 participants were included in this meta-analysis. The pooled HR of all-cause mortality was 1.262 (95 % CI 1.093-1.431) with significant heterogeneity. Subgroup analyses indicated that the pooled HRs of all-cause mortality in patients with mild, moderate and severe OSA were 0.945 (95 % CI 0.810-1.081), 1.178 (95 % CI 0.978-1.378) and 1.601 (95 % CI 1.298-1.902), respectively. OSA severity could be a possible sources of heterogeneity. Existing publication bias produced a minor contribution to effect size.

CONCLUSION

Severe, but not mild to moderate, OSA is significantly associated with increased risk of all-cause mortality.

Progression of obstructive sleep apnoea syndrome in Japanese patients

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Obstructive sleep apnoea in the general population: highly prevalent but minimal symptoms

The aim was to assess the prevalence of obstructive sleep apnoea (OSA) as defined by an apnoea-hypopnea index (AHI) ≥15 in the middle-aged general population, and the interrelationship between OSA, sleep-related symptoms, sleepiness and vigilance.A general population sample of 40-65-year-old Icelanders was invited to participate in a study protocol that included a type 3 sleep study, questionnaire and a psychomotor vigilance test (PVT).Among the 415 subjects included in the study, 56.9% had no OSA (AHI <5), 24.1% had mild OSA (AHI 5-14.9), 12.5% had moderate OSA (AHI 15-29.9), 2.9% had severe OSA (AHI ≥30) and 3.6% were already diagnosed and receiving OSA treatment. However, no significant relationship was found between AHI and subjective sleepiness or clinical symptoms. A relationship with objective vigilance assessed by PVT was only found for those with AHI ≥30. Subjects already on OSA treatment and those accepting OSA treatment after participating in the study were more symptomatic and sleepier than others with similar OSA severity, as assessed by the AHI.In a middle-aged general population, approximately one in five subjects had moderate-to-severe OSA, but the majority of them were neither symptomatic nor sleepy and did not have impaired vigilance.

Cardiovascular comorbidities in obstructive sleep apnoea according to age: a sleep clinic population study

PURPOSE

To describe the features of obstructive sleep apnoea (OSA) and its association with arterial hypertension (HT), coronary artery disease (CAD), and arrhythmias in elderly (≥65 years) versus younger patients.

METHODS

All adult patients referred to our Sleep Research Unit for suspected OSA were included and underwent a thorough medical examination and an in-laboratory polysomnography. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) as mild [5-15/h), moderate [15-30/h), and severe (≥30/h).

RESULTS

Elderly patients (n = 136) and really old patients (>75 years) had higher prevalence of OSA (89 %) and severe OSA (36.8 %) as compared to younger patients (n = 439; 79.5 and 27.6 %, respectively, p < 0.05). In patients with OSA, the elderly group had a poorer sleep quality and more severe nocturnal oxygen desaturation than the younger group. Elderly patients presented higher percentages of HT (47.8 %), CAD (19.8 %), and arrhythmias (16.2 %) as compared to younger patients (p < 0.01). The odds ratio (OR) for HT increased with OSA severity from 1.0 to 1.65 (95 % confidence interval 0.83-3.27), 1.0 to 2.5 (95 % CI 1.25-5.00), and 1.0 to 3.77 (1.95-7.29) in younger patients, but not in elderly ones where the OR increased from 1.0 to 0.6 (0.17-2.04), 1.0 to 1.14 (0.34-3.82), and 1.0 to 1.46 (0.46-4.63), respectively.

CONCLUSION

Stronger relation of HT and OSA severity in younger patients should encourage us to screen OSA in these patients at very young age. Increased OSA severity without obesity in very old patients needs to be confirmed and further studied.

Obstructive sleep apnoea syndrome

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

All-cause mortality from obstructive sleep apnea in male and female patients with and without continuous positive airway pressure treatment: a registry study with 10 years of follow-up

BACKGROUND

More information is needed about the effect on mortality of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA), especially in women.

METHODS

We employed a historical cohort study design, using data from 25,389 patients with a diagnosis of OSA selected from the Danish National Patient Registry for the period 1999-2009. We used Cox proportional hazard function to evaluate the all-cause mortality from OSA in middle-aged and elderly males and females who were treated, or not, with CPAP.

RESULTS

Female OSA patients had a lower mortality than males, irrespective of whether they received CPAP treatment. CPAP treatment improved survival, as illustrated by the hazard ratio of 0.62 (P<0.001). This effect was dependent on gender: CPAP had no significant effect on 20- to 39-year-old males and females, but the overall mortality in this age group was small. Survival was increased by CPAP in 40- to 59-year-old and ≥60-year-old males, but no such effect was observed in females. Positive predictors of survival were young age, female gender, higher educational level, and low 3-year prior comorbidity as estimated by the Charlson Comorbidity Index. Negative predictors for survival were male gender, age ≥60 years, no CPAP treatment, prior comorbidity, and low educational level.

CONCLUSION

CPAP therapy is associated with reduced all-cause mortality in middle-aged and elderly males, but no significant effect was found in females.

Adequate continuous positive airway pressure therapy reduces mortality in Chinese patients with obstructive sleep apnea

BACKGROUND

Severe obstructive sleep apnea (OSA) is a risk factor for mortality. The ability of continuous positive airway pressure (CPAP) therapy to mitigate this increased risk of death has not been studied in Chinese adults. The objective of our study was to compare mortality in Chinese patients with simple snoring, untreated OSA, and OSA treated with CPAP.

METHODS

We recruited adults with OSA or simple snoring from our sleep medicine clinic. OSA was diagnosed using standard polysomnography. Subjects were followed at least annually for a mean of 8.9 years (SD 1.9). CPAP compliance was checked with the built-in meter. We then assessed all-cause mortality.

RESULTS

Five hundred fifty simple snorers, 257 with untreated mild OSA, 316 with untreated moderate OSA, 457 with untreated severe OSA, and 235 with mild to severe OSA treated with CPAP were included. Simple snorers had a much lower mortality rate (2.98 per 1000 person-years [95% CI, 2.93 to 3.02]) than the untreated severe OSA group (11.07 per 1000 person-years [95%CI, 10.86 to 11.29]; P < 0.0001). Compared with simple snorers, fully adjusted mortality was highest in the untreated, severe OSA group (hazard ratio [HR], 3.51 [95%CI, 1.93 to 6.39]). Treatment of severe OSA patients with CPAP eliminated this increase in mortality (HR, 0.81[95%CI, 0.36-1.86]).

CONCLUSIONS

Severe OSA significantly markedly increases the risk of death in Chinese patients and CPAP treatment with adequate compliance reduces this risk.

The effects of continuous positive airways pressure therapy on cardiovascular end points in patients with sleep-disordered breathing and heart failure: a meta-analysis of randomized controlled trials

In patients with sleep-disordered breathing and heart failure, continuous positive airway pressure has been found to be associated with an improvement in cardiovascular end points. We conducted a systematic review of the current literature and a meta-analysis to pool data from 15 published randomized controlled trials. End points analyzed were left ventricular ejection fraction, diastolic blood pressure, systolic blood pressure, heart rate, and mortality. A fixed effects model was used for end points demonstrating homogeneity among included studies, whereas a random effects model was used for end points demonstrating heterogeneity among included studies. A significant improvement in left ventricular ejection fraction was noted with continuous positive airway pressure (mean difference, 5.05%; 95% confidence interval [CI]: 3.72 to 6.38), diastolic blood pressure (mean difference, −1.67; 95% CI: −3.09 to −0.25), and heart rate (mean difference, −5.92; 95% CI: −10.12 to−1.72). No significant changes in mortality (odds ratio, 0.63; 95% CI: 0.40 to 1.00) and systolic blood pressure were noted (mean difference, −6.35; 95% CI: −16.11 to 2.41). The analysis also revealed the need for additional studies to clarify the associations noted and the presence of publication bias with small studies with a paucity of small studies with negative results. In this meta-analysis, treatment with continuous positive airways pressure was associated with improvements in ejection fraction, diastolic blood pressure, and heart rate in patients with sleep-disordered breathing and congestive heart failure.

OSA is common and independently associated with hypertension and increased arterial stiffness in consecutive perimenopausal women

BACKGROUND

Perimenopause is associated with increased cardiovascular risk. OSA is an emerging risk factor for cardiovascular disease, particularly among men, but the independent contribution of OSA to cardiovascular risk in climacteric women is not clear.

METHODS

We evaluated 277 consecutive women (age, 56 [52-61] years; BMI, 28 [25-32] kg/m2) without manifest cardiovascular disease (heart failure, coronary disease, or stroke). All women underwent 24-h ambulatory BP monitoring, arterial stiffness evaluation (pulse wave velocity), and portable sleep study.

RESULTS

OSA (apnea-hypopnea index ≥ 5 events/h) and moderate to severe OSA (apnea-hypopnea index ≥ 15 events/h) were diagnosed in 111 (40.1%) and 31 (11.1%) women, respectively. None of the participants had received a previous diagnosis of OSA. Women with moderate to severe OSA vs those without OSA had a higher prevalence of hypertension, were prescribed more medications for hypertension, had higher awake BP (systolic, 133 [125-142] vs 126 [119-134] mm Hg [P < .01]; diastolic, 82 [78-88] vs 79 [74-85] mm Hg [P = .07]), higher nocturnal BP (systolic, 125 [118-135] vs 115 [109-124] mm Hg [P < .01]; diastolic, 73 [69-79] vs 69 [62-75] mm Hg [P < .01]), and more arterial stiffness (pulse wave velocity, 11.5 [10.1-12.3] m/s vs 9.5 [8.6-10.8] m/s, P < .001). Oxygen desaturation index during the night was independently associated with 24-h arterial BP and arterial stiffness (per five-unit increase in oxygen desaturation index, β = 1.30 [95% CI, 0.02-2.54; P = .04] vs 0.22 [95% CI, 0.03-0.40; P = .02] in women with vs without OSA, respectively).

CONCLUSIONS

OSA is common, underdiagnosed, and independently associated with high BP and increased arterial stiffness in perimenopausal women.

Obstructive sleep apnea and incident diabetes. A historical cohort study

RATIONALE

Despite emerging evidence that obstructive sleep apnea (OSA) may cause metabolic disturbances independently of other known risk factors, it remains unclear whether OSA is associated with incident diabetes.

OBJECTIVES

To evaluate whether risk of incident diabetes was related to the severity and physiologic consequences of OSA.

METHODS

A historical cohort study was conducted using clinical and provincial health administrative data. All adults without previous diabetes referred with suspected OSA who underwent a diagnostic sleep study at St. Michael's Hospital (Toronto, Canada) between 1994 and 2010 were followed through health administrative data until May 2011 to examine the occurrence of diabetes. All OSA-related variables collected from the sleep study were examined as predictors in Cox regression models, controlling for sex, age, body mass index, smoking status, comorbidities, and income.

MEASUREMENTS AND MAIN RESULTS

Over a median follow-up of 67 months, 1,017 (11.7%) of 8,678 patients developed diabetes, giving a cumulative incidence at 5 years of 9.1% (95% confidence interval, 8.4-9.8%). In fully adjusted models, patients with apnea-hypopnea index (AHI) greater than 30 had a 30% higher hazard of developing diabetes than those with AHI less than 5. Among other OSA-related variables, AHI in rapid eye movement sleep and time spent with oxygen saturation less than 90% were associated with incident diabetes, as were heart rate, neck circumference, and sleep time.

CONCLUSIONS

Among people with OSA, and controlling for multiple confounders, initial OSA severity and its physiologic consequences predicted subsequent risk for incident diabetes.

Role of sleep apnea and continuous positive airway pressure therapy in the incidence of stroke or coronary heart disease in women

RATIONALE

It is unknown whether obstructive sleep apnea (OSA) may be a risk factor for incident cardiovascular events in women.

OBJECTIVES

We sought to investigate whether OSA increases the incidence of a composite of stroke or coronary heart disease (CHD) in women, and the role of continuous positive airway pressure (CPAP) treatment on this association.

METHODS

This was a prospective, observational study conducted in two Spanish teaching hospitals between 1998 and 2007. Consecutive women referred for suspected OSA and free of previous stroke and CHD were analyzed. Women with an apnea-hypopnea index (AHI) less than 10 comprised the control group, and those with an AHI greater than or equal to 10 were diagnosed with OSA and classified as CPAP-treated (adherence ≥ 4 h/d) or untreated (adherence < 4 h/d or not prescribed). The follow-up ended in December 2010.

MEASUREMENTS AND MAIN RESULTS

A total of 967 women were studied (median follow-up, 6.8 yr; interquartile range, 5.2-8.2). The untreated OSA group showed a greater incidence rate of the composite outcome than the control group (2.19 vs. 0.54 per 100 person-years; P < 0.0005). Compared with the control group, the fully adjusted hazard ratios for the composite outcome incidence were 2.76 (95% confidence interval [CI], 1.35-5.62) for the untreated OSA group, and 0.91 (95% CI, 0.43-1.95) for the CPAP-treated group. When the type of cardiovascular event was separately assessed, untreated OSA showed a stronger association with incident stroke (adjusted hazard ratio, 6.44; 95% CI, 1.46-28.3) than with CHD (adjusted hazard ratio, 1.77; 95% CI, 0.76-4.09).

CONCLUSIONS

In women, untreated OSA is associated with increased incidence of serious cardiovascular outcomes, particularly incident stroke. Adequate CPAP treatment seems to reduce this risk.

Obstructive sleep apnea and the prevalence and incidence of cancer

BACKGROUND

A link between obstructive sleep apnea and cancer development or progression has been suggested, possibly through chronic hypoxemia, but supporting evidence is limited. We examined the association between the severity of obstructive sleep apnea and prevalent and incident cancer, controlling for known risk factors for cancer development.

METHODS

We included all adults referred with possible obstructive sleep apnea who underwent a first diagnostic sleep study at a single large academic hospital between 1994 and 2010. We linked patient data with data from Ontario health administrative databases from 1991 to 2013. Cancer diagnosis was derived from the Ontario Cancer Registry. We assessed the cross-sectional association between obstructive sleep apnea and prevalent cancer at the time of the sleep study (baseline) using logistic regression analysis. Cox regression models were used to investigate the association between obstructive sleep apnea and incident cancer among patients free of cancer at baseline.

RESULTS

Of 10 149 patients who underwent a sleep study, 520 (5.1%) had a cancer diagnosis at baseline. Over a median follow-up of 7.8 years, 627 (6.5%) of the 9629 patients who were free of cancer at baseline had incident cancer. In multivariable regression models, the severity of sleep apnea was not significantly associated with either prevalent or incident cancer after adjustment for age, sex, body mass index and smoking status at baseline (apnea-hypopnea index > 30 v. < 5: adjusted odds ratio [OR] 0.96, 95% confidence interval [CI] 0.71-1.30, for prevalent cancer, and adjusted hazard ratio [HR] 1.02, 95% CI 0.80-1.31, for incident cancer; sleep time spent with oxygen saturation < 90%, per 10-minute increase: adjusted OR 1.01, 95% CI 1.00-1.03, for prevalent cancer, and adjusted HR 1.00, 95% CI 0.99-1.02, for incident cancer).

INTERPRETATION

In a large cohort, the severity of obstructive sleep apnea was not independently associated with either prevalent or incident cancer. Additional studies are needed to elucidate whether there is an independent association with specific types of cancer.

Attenuated macrophage cholesterol efflux function in patients with obstructive sleep apnea-hypopnea syndrome

BACKGROUND

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is associated with premature atherosclerosis. However, the associated mechanism remains unknown. This study investigates the expression of adenosine triphosphate (ATP)-binding cassette transporter protein A1 (ABCA1) and cellular cholesterol efflux in cultured macrophages from OSAHS patients.

METHODS

Of the 18 subjects enrolled in this study, six subjects with apnea-hypopnea index (AHI) <5 were placed into the control group, and 12 subjects with AHI ≥5 were placed into the OSAHS group. Peripheral blood mononuclear cells (PBMCs) from each subject were isolated, purified, cultured, and differentiated into macrophages in vitro. ABCA1 mRNA and protein expression were evaluated by reverse transcription PCR and Western Blot, respectively. Both ABCA1-mediated and autologous serum induced cholesterol efflux were measured by isotopic cholesterol efflux assays.

RESULTS

The levels of AHI and high sensitivity C-reactive protein (hsCRP) were significantly higher in the OSAHS group than in the control group. ABCA1 mRNA and protein expressions in PBMCs-derived macrophages were significantly reduced in patients with OSAHS compared to that in controls (p < 0.05). Both ABCA1-mediated and autologous serum-induced cholesterol efflux were significantly lower in the OSAHS group than that in the control group (p = 0.033 and p = 0.01, respectively). Pearson's correlation analysis revealed a negative correlation between AHI and the mRNA (r = -0.7726, p = 0.0007) and protein (r = -0.8112, p = 0.0044) expression of ABCA1, a positive correlation between ABCA1-mediated cholesterol efflux and the minimum oxygen saturation (r = 0.7954, p < 0.0001), and a negative correlation between AHI and autologous serum induced cholesterol efflux (r = -0.7756, p = 0.0002).

CONCLUSION

ABCA1 expression and cellular cholesterol efflux in macrophages were significantly decreased in OSAHS patients, which closely correlated with the severity of disease. Our findings provide meaningful insights into the mechanism of atherogenesis in OSAHS patients.

Comparative effectiveness research in obstructive sleep apnea: bridging gaps between efficacy studies and clinical practice

Comparative effectiveness research encompasses research that compares two interventions to each other, and takes place in real-world settings without strict inclusion and exclusion criteria, according to the established standard of care. There is a need for comparative evaluations of the treatments for obstructive sleep apnea, a disease associated with increased cardiovascular risk, stroke and metabolic derangement. This article reviews the recent, representative literature that addresses obstructive sleep apnea intervention and treatment, paradigms for diagnosis and randomized control trials addressing the efficacy of interventions, in an effort to demonstrate examples of both traditional observational and randomized control trials, as well as to illustrate the considerable overlap between some traditional studies and comparative effectiveness research. Despite methodological challenges, the potentially large clinical and public health impact of obstructive sleep apnea, accompanied by considerable cost, mandates that randomized controlled trials and comparative effectiveness research be systematically applied to identify both the efficacy and effectiveness of alternative diagnosis and treatment strategies.

Dichotomous effects of chronic intermittent hypoxia on focal cerebral ischemic injury

BACKGROUND AND PURPOSE

Obstructive sleep apnea, a condition associated with chronic intermittent hypoxia (CIH), carries an increased risk of stroke. However, CIH has been reported to either increase or decrease brain injury in models of focal cerebral ischemia. The factors determining the differential effects of CIH on ischemic injury and their mechanisms remain unclear. Here, we tested the hypothesis that the intensity of the hypoxic challenge determines the protective or destructive nature of CIH by modulating mitochondrial resistance to injury.

METHODS

Male C57Bl/6J mice were exposed to CIH with 10% or 6% O2 for ≤35 days and subjected to transient middle cerebral artery occlusion. Motor deficits and infarct volume were assessed 3 days later. Intraischemic cerebral blood flow was measured by laser-Doppler flowmetry and resting cerebral blood flow by arterial spin labeling MRI. Ca2+-induced mitochondrial depolarization and reactive oxygen species production were evaluated in isolated brain mitochondria.

RESULTS

We found that 10% CIH is neuroprotective, whereas 6% CIH exacerbates tissue damage. No differences in resting or intraischemic cerebral blood flow were observed between 6% and 10% CIH. However, 10% CIH reduced, whereas 6% CIH increased, mitochondrial reactive oxygen species production and susceptibility to Ca2+-induced depolarizations.

CONCLUSIONS

The influence of CIH on the ischemic brain is dichotomous and can be attributed, in part, to changes in the mitochondrial susceptibility to injury. The findings highlight a previously unappreciated complexity in the effect of CIH on the brain, which needs to be considered in evaluating the neurological effect of conditions associated with cyclic hypoxia.

Hypertension and sleep: overview of a tight relationship

Autonomic cardiovascular control changes across sleep stages. Thus, blood pressure (BP), heart rate and peripheral vascular resistance progressively decrease in non-rapid eye movement sleep. Any deterioration in sleep quality or quantity may be associated with an increase in nocturnal BP which could participate in the development or poor control of hypertension. In the present report, sleep problems/disorders, which impact either the quality or quantity of sleep, are reviewed for their interaction with BP regulation and their potential association with prevalent or incident hypertension. Obstructive sleep apnea syndrome, sleep duration/deprivation, insomnia, restless legs syndrome and narcolepsy are successively reviewed. Obstructive sleep apnea is clearly associated with the development of hypertension that is only slightly reduced by continuous positive airway pressure treatment. Shorter and longer sleep durations are associated with prevalent or incident hypertension but age, gender, environmental exposures and ethnic differences are clear confounders. Insomnia with objective short sleep duration, restless legs syndrome and narcolepsy may impact BP control, needing additional studies to establish their impact in the development of permanent hypertension. Addressing sleep disorders or sleep habits seems a relevant issue when considering the risk of developing hypertension or the control of pre-existent hypertension. Combined sleep problems may have potential synergistic deleterious effects.

Untreated obstructive sleep apnea and the risk for serious long-term adverse outcomes: a systematic review

BACKGROUND

Reports on the association between obstructive sleep apnea (OSA) and risk of death, cardiovascular (CV) events, diabetes and depression have been inconsistent.

METHODS

We conducted a systematic review of the prognostic value of clinical and polysomnographic (PSG) characteristics of OSA for adverse long-term outcomes of untreated OSA in adult patients. A comprehensive search strategy for prognosis studies, OSA, CV events, mortality, depression and diabetes was developed in collaboration with a medical information specialist. All English language studies, from Jan 1999 to Dec 2011, with longitudinal design in adults with OSA diagnosed by PSG recording, found through Medline, Embase and bibliographies of identified articles, were considered eligible. Quality was assessed using published guidelines.

RESULTS

Among 26 articles, ten evaluated the association of OSA with mortality, 9 with a composite CV outcome, 4 with stroke, 2 with diabetes and 1 with depression. Significant relationships between the apnea-hypopnea index (AHI) and outcomes of interest were reported in 18 studies: seven for all-cause mortality, six for composite CV events, three for stroke, one for diabetes and one for depression. The effect of AHI was attenuated by female gender, older age, absence of daytime sleepiness and higher body mass index. Due to clinical heterogeneity between studies, meta-analyses were not performed.

CONCLUSION

Evidence exists in men for a relationship between OSA and all-cause mortality and a composite CV outcome. Associations between OSA and other outcomes remain uncertain. Among OSA-specific markers, only AHI was a consistent predictor. Other consistent predictors were traditional CV risk factors. Research is required to identify effect modifiers and the predictive ability of various AHI threshold values and hypopnea definitions. An enhanced set of OSA-specific predictors will allow better risk stratification to guide OSA treatment.

Impact of obstructive sleep apnoea on diabetes and cardiovascular disease

Obstructive sleep apnoea (OSA) is a potential cause of systemic hypertension in young and middle-aged people, and treatment helps reduce blood pressure in some patients. Severe OSA (apnoea-hypopnoea index [AHI] > 30/h) is strongly associated with increased mortality, stroke and cardiovascular disease in middle-aged populations. The cardiovascular risk from moderate OSA (AHI, 15-30/h) is uncertain, particularly if the oxygen desaturation index is low, although the data suggest an increased risk for stroke (particularly in men). There is no evidence of increased cardiovascular risk from mild OSA (AHI < 15/h). In the elderly, the cardiovascular risks of OSA are uncertain, although there is a likelihood of increased risk of stroke. Current, ongoing randomised controlled trials will inform whether OSA is a reversible cardiovascular risk factor within the next 5 years. Patients with cardiovascular disease, stroke, diabetes, obesity or poorly controlled hypertension are at high risk of OSA and should be questioned for symptoms of OSA, which, if present, may warrant further investigation and treatment. Weight loss has an unpredictable effect on OSA severity, but is independently beneficial for symptoms and metabolic health in OSA patients and is recommended for all overweight and obese OSA patients.

Continuous positive airway pressure treatment improves cardiovascular outcomes in elderly patients with cardiovascular disease and obstructive sleep apnea

Obstructive sleep apnea (OSA) is associated with the progression of cardiovascular disease (CVD), particularly in the middle-aged population. However, the clinical importance of OSA as a risk for CVD in the elderly population remains controversial. Moreover, evidence for the effectiveness of continuous positive airway pressure (CPAP) treatment for the secondary prevention of CVD in elderly patients is lacking. We assessed whether CPAP treatment improves cardiovascular outcomes in elderly patients with OSA and CVD. In this retrospective cohort study, we enrolled 130 elderly patients aged 65-86 years with moderate to severe OSA (apnea-hypopnea index ≥15/h) and a history of hospitalization due to CVD, who underwent polysomnography between November 2004 and July 2011. Patients were divided into the CPAP group (n = 64) or untreated OSA group (n = 66). The main outcome measures were cardiovascular death and hospitalization due to CVD. During the mean follow-up period of 32.9 ± 23.8 (standard deviation) months, 28 (21.5 %) patients either died or were hospitalized. The Kaplan-Meier curves indicated that event-free survival was significantly lower in the untreated OSA group than in the CPAP group (P < 0.005). A multivariate analysis showed that the risk was significantly increased in the untreated OSA group (hazard ratio 5.13; 95 % confidence interval 1.01-42.0; P < 0.05). Moderate to severe OSA not treated with CPAP was an independent risk factor for relapse of a CVD event, and adequate CPAP treatment improved cardiovascular outcomes in elderly patients.

Mortality of patients with obstructive sleep apnea in Korea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with diverse health risks, including death. However, the role of OSA as a risk factor for death has never been studied in Asians. This study is aimed at evaluating the influence of OSA on the mortality in Korean sleep clinic population.

METHODS

A total of 2,240 patients who underwent in-laboratory full-night polysomnography due to snoring or sleep apnea were included. The patients were categorized based on apnea-hypopnea index (AHI)/hour. Death records were provided from the Statistics Korea. A Cox-proportional hazard regression model and Kaplan-Meier survival curve were used for analysis and demonstration of the all-cause mortality and cardiovascular mortality.

RESULTS

The all-cause mortality risk adjusted for age, sex, body mass index, diabetes, hypertension, cardiovascular diseases, and previous history of stroke was significantly associated with the increased severity of OSA. The adjusted hazard ratio (HR) for all-cause mortality in the severe OSA group (AHI ≥ 30) vs. reference group (5 < AHI) was 2.47 (95% confidence interval [CI], 1.09-5.57) and the adjusted HR for cardiovascular mortality was 4.66 (CI 1.03-21.08). After adjusting for whether the patients were treated or untreated, the HR for all-cause and cardiovascular mortality in the severe OSA group vs. reference group were 2.14 (p = 0.079) and 4.19 (p = 0.076), respectively.

CONCLUSIONS

The present study showed that the increased mortality was also associated with the increased severity of OSA in Koreans as shown in the studies performed in the Western countries.

Is obstructive sleep apnea associated with cardiovascular and all-cause mortality?

Background

Studies have reported inconsistent findings regarding the association between obstructive sleep apnea (OSA) and future risks of cardiovascular and all-cause mortality. We conducted a meta-analysis to investigate whether OSA is an independent predictor for future cardiovascular and all-cause mortality using prospective observational studies.

Methods

Electronic literature databases (Medline and Embase) were searched for prospective observational studies published prior to December 2012. Only observational studies that assessed baseline OSA and future risk of cardiovascular and all-cause mortality were selected. Pooled hazard risk (HR) and corresponding 95% confidence intervals (CI) were calculated for categorical risk estimates. Subgroup analyses were based on the severity of OSA.

Results

Six studies with 11932 patients were identified and analyzed, with 239 reporting cardiovascular mortality, and 1397 all-cause mortality. Pooled HR of all-cause mortality was 1.19 (95% CI, 1.00 to 1.41) for moderate OSA and 1.90 (95% CI, 1.29 to 2.81) for severe OSA. Pooled HR of cardiovascular mortality was 1.40 (95% CI, 0.77 to 2.53) for moderate OSA and 2.65 (95% CI, 1.82 to 3.85) for severe OSA. There were no differences in cardiovascular mortality in continuous positive airway pressure (CPAP) treatment compared with healthy subjects (HR 0.82; 95% CI, 0.50 to 1.33).

Conclusions

Severe OSA is a strong independent predictor for future cardiovascular and all-cause mortality. CPAP treatment was associated with decrease cardiovascular mortality.

Wireless Wearable Multisensory Suite and Real-Time Prediction of Obstructive Sleep Apnea Episodes

Obstructive sleep apnea (OSA) is a common sleep disorder found in 24% of adult men and 9% of adult women. Although continuous positive airway pressure (CPAP) has emerged as a standard therapy for OSA, a majority of patients are not tolerant to this treatment, largely because of the uncomfortable nasal air delivery during their sleep. Recent advances in wireless communication and advanced ("bigdata") preditive analytics technologies offer radically new point-of-care treatment approaches for OSA episodes with unprecedented comfort and afforadability. We introduce a Dirichlet process-based mixture Gaussian process (DPMG) model to predict the onset of sleep apnea episodes based on analyzing complex cardiorespiratory signals gathered from a custom-designed wireless wearable multisensory suite. Extensive testing with signals from the multisensory suite as well as PhysioNet's OSA database suggests that the accuracy of offline OSA classification is 88%, and accuracy for predicting an OSA episode 1-min ahead is 83% and 3-min ahead is 77%. Such accurate prediction of an impending OSA episode can be used to adaptively adjust CPAP airflow (toward improving the patient's adherence) or the torso posture (e.g., minor chin adjustments to maintain steady levels of the airflow).

Atrial arrhythmias in obstructive sleep apnea: underlying mechanisms and implications in the clinical setting

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive interruption of ventilation during sleep caused by recurrent upper airway collapse, which leads to intermittent hypoxia. The disorder is commonly undiagnosed despite its relationship with substantial cardiovascular morbidity and mortality. Moreover, the effects of the disorder appear to be particularly dangerous in young subjects. In the last decade, substantial clinical evidence has identified OSA as independent risk factor for both bradyarrhythmias and tachyarrhythmias. To date the mechanisms leading to such arrhythmias have not been completely understood. However, recent data from animal models and new molecular analyses have increased our knowledge of the field, which might lead to future improvement in current therapeutic strategies mainly based on continuous positive airway pressure. This paper aims at providing readers a brief and specific revision of current knowledge about the mechanisms underlying atrial arrhythmias in OSA and their clinical and therapeutic implications.

The Relationship between Obstructive Sleep Apnea and Atrial Fibrillation: A Complex Interplay

In recent years, growing evidence suggests an association between obstructive sleep apnea (OSA), a common sleep breathing disorder which is increasing in prevalence as the obesity epidemic surges, and atrial fibrillation (AF), the most common cardiac arrhythmia. AF is a costly public health problem increasing a patient's risk of stroke, heart failure, and all-cause mortality. It remains unclear whether the association is based on mutual risk factors, such as obesity and hypertension, or whether OSA is an independent risk factor and causative in nature. This paper explores the pathophysiology of OSA which may predispose to AF, clinical implications of stroke risk in this cohort who display overlapping disease processes, and targeted treatment strategies such as continuous positive airway pressure and AF ablation.

Mortality in middle-aged men with obstructive sleep apnea in Finland

INTRODUCTION

Obstructive sleep apnea (OSA) has been associated with an elevated rate of cardiovascular mortality. However, this issue has not been investigated in patients with elevated proneness to cardiovascular diseases. Our hypothesis was that OSA would have an especially adverse effect on the risk of cardiovascular mortality in Finnish individuals exhibiting elevated proneness for coronary heart diseases.

METHODS

Ambulatory polygraphic recordings from 405 men having suspected OSA were retrospectively analyzed. The patients were categorized regarding sleep disordered breathing into a normal group (apnea hypopnea index (AHI) < 5, n = 104), mild OSA group (5 ≤ AHI < 15, n = 100), and moderate to severe OSA group (AHI ≥ 15, n = 201). In addition, basic anthropometric and health data were collected. In patients who died during the follow-up period (at least 12 years and 10 months), the primary and secondary causes of death were recorded.

RESULTS

After adjustment for age, BMI, and smoking, the patients with moderate to severe OSA suffered significantly (p < 0.05) higher mortality (hazard ratio 3.13) than their counterparts with normal recordings. The overall mortality in the moderate to severe OSA group was 26.4 %, while in the normal group it was 9.7 %. Hazard ratio for cardiovascular mortality was 4.04 in the moderate to severe OSA and 1.87 in the mild OSA group.

CONCLUSIONS

OSA seems to have an especially adverse effect on the cardiovascular mortality of patients with an elevated genetic susceptibility to coronary heart diseases. When considering that all our patients had possibility of continuous positive airway pressure treatment and our reference group consisted of patients suffering from daytime somnolence, the hazard ratio of 4.04 for cardiovascular mortality in patients with moderate to severe disease is disturbingly high.

Comorbidities and survival in obstructive sleep apnoea beyond the age of 50

BACKGROUND

Although mortality risk associated with obstructive sleep apnoea (OSA) tends to disappear from the age of 50, it has been suggested that OSA treatment by continuous positive airway pressure (CPAP) improves survival even in older subjects. Life expectancy of subjects with several diseases is worse if OSA coexists. The objectives of this study were to evaluate the relevance of comorbidities in the relationship between OSA and mortality, and in the effect of CPAP on survival, in subjects ≥ 50 years old.

METHODS

Data from 810 patients studied by polysomnography for suspected OSA between 1991 and 2000 were retrospectively evaluated. In 2009, state of survival and use of CPAP were enquired. Three hundred and thirteen subjects were < 50 and 497 were ≥ 50 years at diagnosis.

RESULTS

Age and comorbidities, but not apnoea/hypopnoea index (AHI) or lowest nocturnal arterial oxygen saturation (Nadir SaO(2)), predicted mortality in the whole sample. Nadir SaO(2) was related to mortality among the younger subjects without comorbidities (P = 0·01), but not among the older subjects. In the older patients with an AHI > 30 CPAP treatment was associated with a better survival only if comorbidities coexisted.

CONCLUSIONS

Unlike in younger subjects, in subjects ≥ 50 years old, comorbidities do not mask an effect of OSA on mortality. Among OSA subjects ≥ 50 years old, comorbidities could separate those who may expect an improvement in survival with CPAP treatment from those who may not. Possibly, after the age of 50, OSA per se does not affect survival, but worsens prognosis of subjects with coexisting diseases.