Genetic aspects of hypertension and metabolic disease in the obstructive sleep apnoea–hypopnoea syndrome

The pathogenesis of OSA-related hypertension: what are the determining factors?

Sleep-disordered breathing has a relatively high prevalence, which varies from 3-7% in males and from 2-5% in females in the adult population. Studies published in the literature have shown that sleep apnea is closely related to an increased risk of developing various pathologies, among which arterial hypertension stands out. The prevalence of hypertension in patients suffering from obstructive sleep apnea (OSA) ranges from 35-80% and appears to be related to OSA severity. Approximately 40-50% of patients affected by hypertension are also affected by OSA and this association seems to be stronger in young and middle-aged adults (<50 years of age). The primary objective of this narrative review is to provide an update on what are the main contributing comorbidities to the development of a hypertensive state in patients suffering from OSA, an independent risk factor for diurnal hypertension, implicated as a risk factor for the first stroke, recurrent stroke, and post-stroke mortality. There are a lot of factors that contribute to developing a hypertensive state in OSA patients, some more decisive, others less. More evidence from longitudinal studies is needed on the impact of OSA on cardiovascular risk in females, on the causal link between OSA and arterial hypertension or metabolic diseases, like diabetes and glucose intolerance, and the effect of different kinds of OSA treatment.

Integrating the precision, sleep, and aerospace medicine fields: a systematic review of the genetic predisposition for obstructive sleep apnea in military aviation

PURPOSE

Obstructive sleep apnea (OSA) is the most common pathologic sleep disorder with an estimated prevalence in the USA of up to 25% of adult males. With military aviation being heavily comprised of adult men, the impact of OSA on flying operations is concerning as OSA is disqualifying for all flying classes in the US Air Force. In order to minimize the impact of OSA on operations, early identification of at-risk patients is critical in disease management. Individuals could be identified for whom regular polysomnography testing may reveal OSA while mild or sub-clinical, at which point treatment may be initiated in order to promote continued medical qualification for duty and career retention.

METHODS

We performed a keyword search of PubMed, EMBASE, and Google Scholar along with searches in the NHGRI/EBI GWAS Catalogue and the Atlas of GWAS Summary Statistics. We included primary research from candidate gene, GWAS, and meta-analyses. We also included other review articles in our search to confirm interpretations and implications of any genetic associations with OSA. Only studies related to OSA susceptibility or risk were included.

RESULTS

We identified 134 publications reporting or reviewing genetic associations with OSA risk. These papers reported 301 variants, of which 195 were unique and 33 were replicated in at least two papers. With respect to the strength of association, 43 variants exhibited odds ratios greater than 2. Finally, there were 84 null results reported, 51 of which were in conflict with reported associations.

CONCLUSION

There is ample evidence in the literature to confirm that genetics provide an important contribution to OSA development. The high number of strongly associated variants suggests that a polygenic risk model could be created with high predictive value for prognostic screening.

Continuous Positive Airway Pressure in Patients With Obstructive Sleep Apnea and Resistant Hypertension: A Meta-Analysis of Randomized Controlled Trials

This study aimed to analyze the effect of continuous positive airway pressure (CPAP) on blood pressure (BP) in patients with obstructive sleep apnea (OSA) and resistant hypertension. Randomized controlled trials (RCTs) that evaluated the effect of CPAP on BP in patients with OSA and resistant hypertension, indexed in MEDLINE, Embase, and the Cochrane Library from inception until March 20, 2015, were included in the meta-analysis. A total of five RCTs were identified to meet the inclusion criteria. The pooled changes after CPAP treatment for 24-hour ambulatory systolic BP and diastolic BP (DBP) were -4.78 mm Hg (95% confidence interval [CI], -7.95 to -1.61) and -2.95 mm Hg (95% CI, -5.37 to -0.53) in favor of the CPAP group. CPAP was also associated with reduction in nocturnal DBP (mean difference, -1.53 mm Hg, 95% CI, -3.07 to 0). The results indicated a favorable reduction in BP with CPAP treatment in patients with OSA and resistant hypertension.

Position paper on the management of patients with obstructive sleep apnea and hypertension: joint recommendations by the European Society of Hypertension, by the European Respiratory Society and by the members of European COST (COoperation in Scientific and Technological research) ACTION B26 on obstructive sleep apnea

This article is aimed at addressing the current state of the art in epidemiology, pathophysiology, diagnostic procedures and treatment options for appropriate management of obstructive sleep apnea (OSA) in cardiovascular (particularly hypertensive) patients, as well as for the management of cardiovascular diseases (particularly arterial hypertension) in OSA patients. The present document is the result of the work done by a panel of experts participating in the European Union COST (COoperation in Scientific and Technological research) ACTION B26 on OSA, with the endorsement of the European Respiratory Society (ERS) and the European Society of Hypertension (ESH). These recommendations are particularly aimed at reminding cardiovascular experts to consider the occurrence of sleep-related breathing disorders in patients with high blood pressure. They are at the same time aimed at reminding respiration experts to consider the occurrence of hypertension in patients with respiratory problems at night.

Obstructive sleep apnea and the metabolic syndrome

Obstructive sleep apnea (OSA) and the metabolic syndrome have a strong association with each other owing to their common feature of obesity, but an association independent of obesity has been demonstrated in several studies. There is also evidence, of varying strengths, from epidemiologic and clinical studies, for the independent association between OSA and individual core components of the metabolic syndrome, including hypertension, insulin resistance and dyslipidemia. To date, the data are strongest for hypertension, while data for adverse glucose or lipid metabolism are more controversial. Obesity and other factors, such as alcohol drinking and smoking, obviously pose major confounding hurdles to the clarification of the causal or aggravational role of OSA on cardiometabolic risks. Recurrent episodes of obstructed breathing notably result in intermittent hypoxemia and sleep fragmentation, and these may in turn lead to many adverse body responses, including sympathetic activation, neurohumeral changes and inflammation, which are the seeds for cardiometabolic dysfunctions, such as atherosclerosis and diabetes mellitus. Evidence from translational studies or animal/cell work are forthcoming in the delineation of these pathogenetic mechanisms.

Clinical assessment of the obstructive sleep apnoea/hypopnoea syndrome

This review focuses on the clinical presentation of the obstructive sleep apnoea/hypopnoea syndrome in adults. Features consistent with the diagnosis are described. A brief discussion of the objective measurement of sleep-disordered breathing, largely in the form of overnight monitoring, is undertaken.

Obstructive sleep apnea and cardiovascular disease: a perspective and future directions

Data from animal and human studies provide a biological plausibility to the notion that obstructive sleep apnea activates pathways that lead to insulin resistance, atherosclerosis and hypertension. Sleep apnea thus activates the same pathways as does obesity. That obstructive sleep apnea is a risk factor for cardiovascular disease is supported by epidemiological association studies. Longitudinal cohort studies also provide evidence that patients with untreated severe sleep apnea have an increased rate of cardiovascular events. But these studies, while highly suggestive, do not provide the evidence needed to convince the skeptic. This would only be obtained by randomized treatment trials with hard cardiovascular endpoints such as cardiac events and deaths. While such studies are in the planning stages, they will be challenging. There are issues about randomizing individuals with severe sleep apnea and excessive sleepiness into no therapy, since they are at known increased risk for car crashes. Thus, lack of therapy puts others on the road at risk as well as the subject with sleep apnea. There is, moreover, the concern that treating obstructive sleep apnea in very obese individuals will have little impact, since any effect of therapy for OSA will be overwhelmed by the effects of obesity itself. Data from randomized treatment trials for cardiovascular endpoints will likely not be available for many years. In the interim, physicians need to consider how to treat such patients. It is proposed that given that CPAP treatment for obstructive sleep apnea is highly effective and essentially totally safe, and that the evidence is suggestive that sleep apnea is a risk factor for cardiovascular disease, then we propose all patients with severe sleep apnea should be treated to reduce cardiovascular risk.

Sleep-wake schedules in preschool children who snore

PURPOSE

The aim of the study was to compare sleep-wake schedules between snoring and nonsnoring preschool age children.

MATERIAL AND METHODS

Daytime and nighttime sleep duration, daytime and nighttime symptoms were assessed in 34 children at preschool age who snore (5.38+/-1.21 years) and in 66 age- and sex-matched nonsnorers (5.67+/-1.12 years). The snoring group consisted of children with obstructive sleep apnea (OSA) scores <+3.5 and >-1, the nonsnoring group with OSA score <-1.

RESULTS

Children who snore differ from the nonsnorers in daytime sleep duration (51.62+/-28.9 minutes vs. 10.70+/-20.2 minutes; p<0.001), but not in nighttime sleep (10.97+/-0.52 hours vs. 9.83+/-1.34 hours; p>0.05). The percentage of children with daytime napping was higher in the snoring group than in the nonsnorers (47.1% vs. 9.1%; p<0.00004), and parents-reported behavioral problems were more frequent in children who snore (41.2% vs. 19.7%; p<0.02). Multivariate odds ratios, including variables for nighttime (sleep apnea) and daytime symptoms (daytime napping and oral breathing), showed that regular sleep during the day was the most predictive of snoring (OR=6.1; 95%CI 1.76-21.04; p<0.005).

CONCLUSION

In preschool age children, when the daytime nap begins to disappear, snoring may have an effect on daytime schedule through an increased need for daytime sleep.