The role of obesity, different fat compartments and sleep apnea severity in circulating leptin levels: the Icelandic Sleep Apnea Cohort study

Association of Backscattered Ultrasonographic Imaging of the Tongue With Severity of Obstructive Sleep Apnea in Adults

Importance

Determining interventions to manage obstructive sleep apnea (OSA) depends on clinical examination, polysomnography (PSG) results, and imaging analysis. There remains the need of a noninvasive and cost-effective way to correlate relevant upper airway anatomy with severity of OSA to direct treatment and optimize outcome.

Objective

To determine whether backscattered ultrasonographic imaging (BUI) analysis of the tongue is associated with severity of OSA in adults.

Design, Setting, and Participants

In this prospective, single-center, diagnostic study of a consecutive series of patients (aged ≥18 years) at a sleep surgery clinic, the 89 included patients had a PSG within 3 years at the time of ultrasonography and BUI analysis between July 2020 and March 2022. Patients were excluded if body mass index had changed more than 10% since time of PSG. A standardized submental ultrasonographic scan with laser alignment was used with B-mode and BUI analysis applied to the tongue. The B-mode and BUI intensity were associated with the apnea-hypopnea index (AHI), a measure of severity of apnea from normal (no OSA) to severe OSA.

Exposures

Ultrasonography and PSG.

Main Outcomes and Measures

The main outcomes were BUI parameters and their association with AHI value.

Results

Eighty-nine patients were included between July 2020 and March 2022. A total of 70 (78.7%) male patients were included; and distribution by race and ethnicity was 46 (52%) White participants, 22 (25%) Asian participants, and 2 (2%) African American participants, and 19 (21%) others. Median (IQR) age was 37.0 (29.0-48.3) years; median (IQR) BMI was 25.3 (23.2-29.8); and median (IQR) AHI was 11.1 (5.6-23.1) events per hour. At the middle to posterior tongue region, the 4 OSA severity levels explained a significant portion of the BUI variance (η2 = 0.153-0.236), and a significant difference in BUI values was found between the subgroups with AHI values of less than 15 (no OSA and mild OSA) and greater than or equal to 15 (moderate OSA and severe OSA) events per hour. The echo intensity showed no significant differences. The BUI values showed a positive association with AHI, with a Spearman correlation coefficient of up to 0.43. Higher BUI values remained associated with higher AHI after correction for the covariates of BMI and age.

Conclusions and Relevance

In this prospective diagnostic study, standardized BUI analysis of the tongue was associated with OSA severity. With the practicality of ultrasonography, this analysis is pivotal in connecting anatomy with physiology in treatment planning for patients with OSA.

Upper airway modifications after weight loss: a systematic review

OBJECTIVE

Weight loss is one of the most often prescribed treatments to reduce the level of sleep apnea severity; however, objective assessment of airway alterations after loss of weight has only been studied in the last decades. This study aimed at evaluating alterations after weight loss reported in the literature.

METHODS

A literature review was performed in the medical databases: PubMed, Web of Science, Scopus and Embase. A total of 681 articles were found in the databases and after evaluation only 10 studies were selected for data extraction.

RESULTS

Most studies observed an increase of the area in the retropalatal region; some indicating that this increase occurred mostly in the lateral pharyngeal region. Studies with volumetric reconstruction showed a significant reduction in parapharyngeal fat deposits, lateral wall and tongue fat, and volumetric reduction in all soft tissues of the pharynx, pterygoid and genioglossus muscles. Studies evaluating craniofacial bone structures showed a reduction in the airway height by bringing the hyoid closer to the posterior nasal spine and a reduction in the distance from the hyoid to the chin.

CONCLUSION

There is a limited number of studies with a good level of scientific evidence evaluating changes in the upper airways after weight loss and how these changes impact obstructive sleep apnea. The studies included in this review indicate that weight loss increases the airways space by reducing the volume of the parapharyngeal structures, particularly at the retropalatal site, where there is an apparent gain in the lateral area of the airway and hyoid relocation.

Obstructive Sleep Apnoea and Lipid Metabolism: The Summary of Evidence and Future Perspectives in the Pathophysiology of OSA-Associated Dyslipidaemia

Obstructive sleep apnoea (OSA) is associated with cardiovascular and metabolic comorbidities, including hypertension, dyslipidaemia, insulin resistance and atherosclerosis. Strong evidence suggests that OSA is associated with an altered lipid profile including elevated levels of triglyceride-rich lipoproteins and decreased levels of high-density lipoprotein (HDL). Intermittent hypoxia; sleep fragmentation; and consequential surges in the sympathetic activity, enhanced oxidative stress and systemic inflammation are the postulated mechanisms leading to metabolic alterations in OSA. Although the exact mechanisms of OSA-associated dyslipidaemia have not been fully elucidated, three main points have been found to be impaired: activated lipolysis in the adipose tissue, decreased lipid clearance from the circulation and accelerated de novo lipid synthesis. This is further complicated by the oxidisation of atherogenic lipoproteins, adipose tissue dysfunction, hormonal changes, and the reduced function of HDL particles in OSA. In this comprehensive review, we summarise and critically evaluate the current evidence about the possible mechanisms involved in OSA-associated dyslipidaemia.

Obstructive sleep apnea: personalizing CPAP alternative therapies to individual physiology

Introduction The recent continuous positive airway pressure (CPAP) crisis has highlighted the need for alternative obstructive sleep apnea (OSA) therapies. This article serves to review OSA pathophysiology and how sleep apnea mechanisms may be utilized to individualize alternative treatment options.Areas covered: The research highlighted below focuses on 1) mechanisms of OSA pathogenesis and 2) CPAP alternative therapies based on mechanism of disease. We reviewed PubMed from inception to July 2022 for relevant articles pertaining to OSA pathogenesis, sleep apnea surgery, as well as sleep apnea alternative therapies.Expert opinion: Although the field of individualized OSA treatment is still in its infancy, much has been learned about OSA traits and how they may be targeted based on a patient's physiology and preferences. While CPAP remains the gold-standard for OSA management, several novel alternatives are emerging. CPAP is a universal treatment approach for all severities of OSA. We believe that a personalized approach to OSA treatment beyond CPAP lies ahead. Additional research is needed with respect to implementation and combination of therapies longitudinally, but we are enthusiastic about the future of OSA treatment based on the data presented here.

Interactions between Obstructive Sleep Apnea Syndrome Severity, Obesity, Sex Difference and Attention-Deficit/Hyperactivity Disorder on Health-Related Quality of Life: A Non-Interventional Prospective Observational Study

Obstructive sleep apnea syndrome (OSAS) severity, obesity, sex difference, and attention-deficit/hyperactivity disorder (ADHD) had a complex impact on health-related quality of life (HRQoL). However, the interactive effects among these features on HRQoL remained to be clarified. This study aimed to investigate the individual and interactive associations between the four characteristics of interest and HRQoL as determined by 36-Item Short Form Health Survey, Pittsburgh Sleep Quality Index (PSQI), and Epworth Sleepiness Scale (ESS). This non-interventional, prospective, observational study enrolled a total of 132 patients with suspected OSAS for analysis. While OSAS severity and ADHD detected by adult ADHD Self-Report Scale, termed as screened ADHD, interact with each other, all the four studied features were individually associated with HRQoL. After adjusting for potential physiological and polysomnographic confounders, screened ADHD was independently correlated with PSQI > 5 (OR = 4.126, 95% CI, 1.490−11.424), mental component score < 50 (OR = 5.873, 95% CI, 2.262−15.251) and ESS > 10 (OR = 3.648, 95% CI, 1.738−7.657). Our results show that ADHD detection is necessary and should be incorporated into clinical practice for OSAS management.

The Impact of Sleep-Disordered Breathing on Ghrelin, Obestatin, and Leptin Profiles in Patients with Obesity or Overweight

Background: The impact of concomitant obesity and sleep disorders on neuropeptides related to energy balance is poorly understood. The aim of this study was to assess the nocturnal profile of total ghrelin, obestatin, and leptin in patients with elevated BMI and to investigate the impact of breathing-related sleep disorders on these hormone levels. Methods: The study involved 58 patients with suspicion of obstructive sleep apnea (OSA). Patients underwent anthropometric and sleep examination and measurements of night ghrelin, leptin, and obestatin levels. Results: In patients with OSA (n = 46), recognized on the basis of sleep examination outcomes, the correlation of anthropometric measurements with parameters of sleep disorders and ghrelin levels was observed, contrary to the control group (n = 12). In the OSA group, levels of ghrelin were significantly lower than in the control group at 5:00 and 7:00. Levels of leptin in the OSA group were also lower than those in the control groups (not statistically significant). Profiles of obestatin in both groups were similar. Conclusions: Our results confirm the relationship between obesity and sleep-disordered breathing. Both these disorders affect ghrelin levels—parameters of obesity negatively correlate with hormone concentration, and OSA seems to lower ghrelin values in the second half of the night.

Pediatric obstructive sleep-disordered breathing is associated with arterial stiffness

The association between obstructive sleep-disordered breathing (oSDB) and arterial stiffness, an independent predictor of cardiovascular outcomes, is not well established in children. This study compared cardiovascular parameters between healthy and oSDB children and aimed to identify predictors of arterial stiffness indices in children with oSDB. Cross-sectional study realized in a tertiary hospital from June 2018 to January 2020. Forty-eight children (3 to 10 years old) with clinical diagnosis of oSDB and indication for adenotonsillectomy and 24 controls were evaluated. Cardiovascular parameters were measured non-invasively by brachial artery oscillometry with a portable device. The main arterial stiffness indices assessed were augmentation index and pulse wave velocity, both derived from the aortic pulse wave. In the oSDB group, the questionnaires Obstructive Sleep Apnea-18 (OSA-18) and Pediatric Quality of Life Inventory version 4.0 (PedsQL 4.0) were applied. The oSDB group had higher values of reflection coefficient (p = 0.044) and augmentation index (p = 0.003) than the control group. Stepwise multiple regression analysis revealed that age, female sex, reflection coefficient, and systolic volume were independent predictors of augmentation index. Higher pulse wave velocity values were associated with worse quality of life assessed by PedsQL 4.0 questionnaire. There was no association with OSA-18. The vascular and hemodynamic parameters were similar in both groups.Conclusion: Children with oSDB have increased augmentation index, an independent predictor of cardiovascular outcomes. The early identification of subclinical cardiovascular changes reinforces the importance of treating the disease, as well as changing lifestyle habits, to prevent complications in adulthood. What is Known: • The association between oSDB and cardiovascular risk in adults is well described in the literature. • Children with oSDB, regardless of their weight or sex, have higher PWV values when compared to non-snoring children. What is New: • Children with oSDB have augmented arterial stiffness, evidenced by the increase in AIx@75, measured non-invasively by brachial artery oscillometry with a portable device. • Low quality of life and therefore a high disease burden in children with oSDB may be a risk factor for arterial stiffness.

Associations of Obstructive Sleep Apnea, Obestatin, Leptin, and Ghrelin with Gastroesophageal Reflux

Gastroesophageal reflux disease (GERD) is commonly observed in patients with obstructive sleep apnea (OSA). Hormonal disorders observed in OSA may be relevant in the development of GERD. The aim of the study was to assess the correlations between ghrelin, obestatin, leptin, and the intensity of GERD in patients with OSA. The study included 58 patients hospitalized due to clinical suspicion of sleep disorders during sleep. All patients underwent a sleep study, and blood samples were collected overnight for hormonal tests. Survey data concerning symptoms of GERD, gastroscopy, and esophageal pH monitoring results were included in the study. In patients with OSA, GERD was twice as common when compared to the group without OSA. Among subjects with severe sleep apnea (AHI > 30; n = 31; 53%), we observed lower ghrelin levels, especially in the second half of the night and in the morning (p_5.00 = 0.0207; p_7.00 = 0.0344); the presence of OSA had no effect on obestatin and leptin levels. No significant differences in hormonal levels were observed between the groups depending on the diagnosis of GERD. However, correlations of ghrelin levels with the severity of esophagitis, leptin and ghrelin levels with the severity of GERD symptoms, and leptin levels with lower esophageal pH were found. GERD is more frequent among patients with OSA. In both GERD and OSA, deviations were observed in the levels of ghrelin and leptin. However, our analysis demonstrates that the relationship between OSA and GERD does not result from these disorders.

Association of Visceral Adiposity Index, Lipid Profile, and Serum Leptin with Glucose Intolerance Risks in Iraqi Obese Patients: A Cross-sectional Study

Aims:

The aim of this study was to evaluate the possibility of using visceral adiposity index (VAI), serum leptin, and lipid profile as indicators of impaired glucose tolerance in Iraqi obese patients.

Subjects and Methods:

A cross-sectional study was performed in Iraqi obese patients of both sexes. Body mass index (BMI), waist circumference, hip circumference, triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), VAI, waist-to-hip ratio (WHR), serum leptin, and 2-h glucose tolerance test (2-h GT) were determined and compared with those of healthy non-obese control group. A correlation analysis was performed to determine the strength of association between the studied markers. Data were adjusted to determine gender differences in this regard.

Statistical Analysis:

Kolmogorov–Smirnov, Shapiro–Wilk analyses, Mann–Whitney U test, and unpaired t test were used for the two-group comparisons once applicable. Pearson’s and Spearman’s correlation analyses were used to measure the relationship levels between the studied variables.

Results:

A total of 144 obese patients were included; the mean age was 37.11 ± 8.2 years and 92 (63.9%) were females. Compared with non-obese subjects, the participants had significantly higher levels of BMI, WC, WHR, VAI, TG, leptin, and 2-h GTObese male subjects had significantly higher values of body weight, WC, HC, VAI, and TG compared with obese females. Elevated 2-h GT was significantly associated with VAI (r = 0.291, P = 0.0004), TG (r = 0.319, P = 0.0001), and LDL-C/HDL-C ratio (r = 0.435, P < 0.0001) in the obese patients only.

Conclusions:

The results provide evidence that VAI, TG, and LDL-C/HDL-C ratio can be suggested as potential markers for the risk assessment of impaired glucose tolerance in Iraqi obese patients.

Interactions among Obstructive Sleep Apnea Syndrome Severity, Sex, and Obesity on Circulatory Inflammatory Biomarkers in Patients with Suspected Obstructive Sleep Apnea Syndrome: A Retrospective, Cross-Sectional Study

The interaction among obstructive sleep apnea syndrome (OSAS) severity, sex, and obesity on cardiovascular risk as determined by serum levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) remains unclear. Therefore, this study aimed to analyze individual associations between these three OSAS characteristics and three cardiovascular biomarkers and to determine whether the relationship was affected by other features in patients with suspected OSAS. For all participants (n = 100), OSAS severity and sex had an interaction effect on IL-6 level (p = 0.030). Specifically, the male patients (p = 0.005) with severe OSAS had higher IL-6 levels than those with normal to moderate OSAS, but this relationship was not significant in the female patients (p = 0.438). Moreover, in patients with normal to moderate OSAS (p = 0.004), but not in those with severe OSAS (p = 0.824), the female patients had higher IL-6 levels than the male patients. Both CRP (p = 0.001) and IL-6 (p = 0.000) levels were higher in the obese group than in the non-obese group independently of OSAS severity and sex. The three features had no effects on TNF-α level individually and interactively. Our findings suggest that circulatory inflammatory markers should be comprehensively evaluated in this population and that treatment and preventive therapies should be modified accordingly.

Differences in three-dimensional upper airway anatomy between Asian and European patients with obstructive sleep apnea

STUDY OBJECTIVES

This study evaluated differences in upper airway, soft tissues and craniofacial structures between Asians from China and Europeans from Iceland with OSA using three-dimensional magnetic resonance imaging (MRI).

METHODS

Airway sizes, soft tissue volumes, and craniofacial dimensions were compared between Icelandic (N = 108) and Chinese (N = 57) patients with oxygen desaturation index (ODI) ≥ 10 events/h matched for age, gender, and ODI. Mixed effects models adjusting for height or BMI and residual differences in age and ODI were utilized.

RESULTS

In our matched sample, compared to Icelandic OSA patients, Chinese patients had smaller BMI (p < 0.0001) and neck circumference (p = 0.011). In covariate adjusted analyses, Chinese showed smaller retropalatal airway size (p ≤ 0.002), and smaller combined soft tissues, tongue, fat pads, and pterygoid (all p ≤ 0.0001), but male Chinese demonstrated a larger soft palate volume (p ≤ 0.001). For craniofacial dimensions, Chinese demonstrated bigger ANB angle (p ≤ 0.0196), differently shaped mandibles, including shorter corpus length (p < 0.0001) but longer ramus length (p < 0.0001), and a wider (p < 0.0001) and shallower (p ≤ 0.0001) maxilla.

CONCLUSIONS

Compared to Icelandic patients of similar age, gender and ODI, Chinese patients had smaller retropalatal airway and combined soft tissue, but bigger soft palate volume (in males), and differently shaped mandible and maxilla with more bony restrictions. Results support an ethnic difference in upper airway anatomy related to OSA, which may inform targeted therapies.

The Impact of Obstructive Sleep Apnea and Positive Airway Pressure Therapy on Metabolic Peptides Regulating Appetite, Food Intake, Energy Homeostasis, and Systemic Inflammation: A Literature Review

INTRODUCTION

Sleep-related breathing disorders are very common and highly associated with many comorbid diseases. They have many metabolic consequences that impact appetite, energy expenditure, and systemic inflammation. These consequences are mediated through peptides (eg, ghrelin, leptin, adiponectin, resistin, apelin, obestatin, and neuropeptide Y).

METHODS

We searched the literature (PubMed) for sleep-disordered breathing (SDB) and metabolic peptides and included 15, 22, 14, 4 and 2 articles for ghrelin, leptin, adiponectin, resistin, and apelin respectively.

RESULTS

Our review of the published literature suggests that leptin levels seem to correlate with body mass index and adiposity rather than obstructive sleep apnea. Conversely, levels of adiponectin and ghrelin are influenced by obstructive sleep apnea alone. Finally, resistin and apelin seem to be not correlated with obstructive sleep apnea. Regarding positive airway pressure (PAP) impact, it seems that PAP therapy affected the levels of these peptides (mainly ghrelin).

CONCLUSIONS

There is significant controversy in the literature regarding the impact of SDB and PAP therapy on these metabolic peptides. This could be due to the lack of randomized clinical trials and the variability of the methodology used in these studies. Further research is needed to assess the impact of SDB and PAP therapy on the levels of these peptides and whether this impact is also related to body mass index and body fat composition.

Leptin and adiponectin levels in obstructive sleep apnea phenotypes

Objective: To examine the serum levels of leptin and adiponectin in different obstructive sleep apnea (OSA) phenotypes. Methods: Obese patients who were admitted to our sleep laboratory were included. All patients underwent spirometry, daytime arterial blood gas analysis, polysomnography and transthoracic echocardiography. Serum levels of adiponectin and leptin were recorded. Results: Analysis included 146 OSA patients (81 females, 65 males, age: 49.8 ± 10.7 years, body mass index: 40.3 ± 4.9 kg/m², 47.9% severe OSA, 42.5% severe obesity). Females had higher leptin and adiponectin levels (p < 0.001; p < 0.001, respectively). Leptin levels were higher in patients with severe obesity (p < 0.001). Severe OSA patients had lower leptin and adiponectin levels (p = 0.023; p = 0.035, respectively). Conclusion: Adipokine levels were different especially in OSA patients with severe obesity, female gender and severe OSA.

Role of Obesity in Otorhinolaryngologic Diseases

PURPOSE OF REVIEW

Obesity is a major public health problem associated with various diseases. Improving obesity control and achieving greater patient satisfaction are critical unmet needs. Various otorhinolaryngologic diseases can have negative effects on quality of life or actual health status depending on their type. Over the past decade, the relationship between obesity and otorhinolaryngologic conditions has been investigated. The purpose of this review was to discuss the relationship between obesity and otorhinolaryngological diseases.

RECENT FINDINGS

This is a narrative review on the current state of incidence, effects, and associated mechanisms between obesity and otorhinolaryngologic diseases. In various otologic diseases, otitis media (OM) and hearing loss (HL) are associated with obesity. In rhinologic parts, chronic rhinosinusitis (CRS) and obstructive sleep apnea (OSA) were significantly associated with obesity. Most of these diseases are reported to have higher susceptibility and severity as body mass index (BMI) increases. However, the incidence of head and neck cancer (HNC) was inversely associated with obesity, especially central adiposity. The relevance of obesity in laryngopharyngeal reflux disease (LPR) and allergic rhinitis (AR) has yet to be clarified, and this remains controversial. This review provides a comprehensive overview of the current state of incidence, effects, and associated mechanisms between obesity and otorhinolaryngologic diseases. Various otorhinolaryngological diseases are related to obesity. As obesity can be a negative risk factor in these otorhinolaryngologic diseases, early diagnosis and treatment of these diseases in obese patients will be critical.

Changing Faces of Obstructive Sleep Apnea: Treatment Effects by Cluster Designation in the Icelandic Sleep Apnea Cohort

Study Objectives

Distinct clinical phenotypes of obstructive sleep apnea (OSA) have been identified: Disturbed Sleep, Minimally Symptomatic, and Sleepy. Determining whether these phenotypes respond differently to standard treatment helps us to create a foundation for personalized therapies. We compared responses to positive airway pressure (PAP) therapy in these clinical OSA phenotypes.

Methods

The study sample included 706 patients from the Icelandic Sleep Apnea Cohort with moderate-to-severe OSA who were prescribed PAP. Linear and logistic mixed models were used to compare 2-year changes in demographics, comorbid diseases, and sleep-related health issues within and across OSA clinical phenotypes. Relationships between changes in symptoms and PAP adherence were also examined.

Results

Overall, effect sizes were moderate to large when comparing sleepiness, insomnia-related, and apneic symptom changes in the Sleepy group with changes in other two groups, especially those in the Minimally Symptomatic group. Within the Disturbed Sleep group, PAP users and nonusers demonstrated similar changes in insomnia-related symptoms. The Minimally Symptomatic group remained relatively asymptomatic, but reported significant decreases in daytime sleepiness and physical fatigue; PAP users generally had larger improvements. The Sleepy group had reductions in nearly all measured symptoms, including large reductions in drowsy driving; almost all of these improvements were greater among PAP users than nonusers.

Conclusions

OSA treatment response patterns differed by initial clinical phenotype and PAP adherence. Individuals with insomnia-related symptoms may require additional targeted therapy for these complaints. These findings underscore the need for a personalized approach to management that recognizes patients with a range of OSA presentations.

Prediction of Circulating Adipokine Levels Based on Body Fat Compartments and Adipose Tissue Gene Expression

BACKGROUND

Adipokines are hormones secreted from adipose tissue (AT), and a number of them have been established as risk factors for chronic diseases. However, it is not clear whether and to what extent adiposity, gene expression, and other factors determine their circulating levels.

OBJECTIVES

To assess to what extent adiposity, as measured by the amount of subcutaneous AT (SAT) and visceral AT (VAT) using magnetic resonance imaging, and gene expression levels in SAT determine plasma concentrations of the adipokines adiponectin, leptin, soluble leptin receptor, resistin, interleukin 6, and fatty acid-binding protein 4 (FABP4).

METHODS

We performed a cross-sectional analysis of 156 participants from the EPIC Potsdam cohort study and analyzed multiple regression models and partial correlation coefficients.

RESULTS

For leptin and FABP4 concentrations, 81 and 45% variance were explained by SAT mass, VAT mass, and gene expression in SAT in multivariable regression models. For the remaining adipokines, AT mass and gene expression explained <16% variance of plasma concentrations. Gene expression in SAT was a less important predictor compared to AT mass. SAT mass was a better predictor than VAT mass for leptin (partial correlation r = 0.81, 95% confidence interval 0.75-0.86, vs. r = 0.58, 95% confidence interval 0.46-0.67), while differences between AT compartments were small for the other adipokines.

CONCLUSIONS

While plasma levels of leptin and FABP4 can be explained in a large and medium part by the amount of AT and SAT gene expression, surprisingly, these predictors explained only little variance for all other investigated adipokines.

PAP treatment in patients with OSA does not induce long-term nasal obstruction

We hypothesized that positive airway pressure treatment would induce nasal obstruction and decrease nasal cavity due to mucosal swelling. We further hypothesized that subjective and objective nasal obstruction at baseline would negatively affect positive airway pressure adherence. A total of 728 patients with sleep apnea were investigated in the Icelandic Sleep Apnea Cohort at baseline and 2 years after starting positive airway pressure. Patients underwent home sleep apnea testing at baseline. Questionnaires were answered and acoustic rhinometry was completed at baseline and follow‐up. The proportion of patients reporting subjective nocturnal nasal obstruction was reduced (baseline: 35% versus follow‐up: 24%; p < 0.001). Small interior nasal dimensions increased (p < 0.001) independent of adherence to treatment. Small nasal volume at baseline was a determinant for becoming a non‐user of positive airway pressure treatment (odds ratio 2.22, confidence interval 95% 1.35–3.67, p = 0.002). Subjective nasal obstruction decreased 2 years after initiating positive airway treatment in sleep apnea, and objectively small nasal dimensions increased. Small nasal volume at baseline was a negative predictor for positive airway pressure treatment adherence. Maybe most importantly, positive airway pressure treatment did not cause long‐term objective or subjective nasal obstruction.

Role of Leptin in Obstructive Sleep Apnea

Leptin is a peptide hormone produced mainly in white adipose tissue. It is known to regulate energy homeostasis, inflammation, metabolism, and sympathetic nerve activity. Increasing evidence suggests it has a role in ventilatory function and upper airway obstruction. Leptin levels correlate positively with measurements of adiposity and can potentially provide important insights into the pathophysiology of diseases associated with obesity. Obesity is a strong risk factor for obstructive sleep apnea, a disease characterized by periodic upper airway occlusion during sleep. The neuromuscular activity that maintains upper airway patency during sleep and the anatomy of upper airway are key factors involved in its pathogenesis. Experimental studies using animal models of a low leptin state such as leptin deficiency have shown that leptin regulates sleep architecture, upper airway patency, ventilatory function, and hypercapnic ventilatory response. However, findings from human studies do not consistently support the data from the animal models. The effect of leptin on the pathophysiology of obstructive sleep apnea is being investigated, but the results of studies have been confounded by leptin's diurnal variation and the short-term effects of feeding, adiposity, age, and sex. Improved study design and methods of assessing functional leptin levels, specifically their central versus peripheral effects, will improve understanding of the role of leptin in sleep apnea.

Relationship of serum leptin with some biochemical, anthropometric parameters and abdominal fat volumes as measured by magnetic resonance imaging

AIMS

To measure the level of leptin in volunteers and correlate it with several anthropometric, biochemical variables and abdominal fat volumes.

METHODS

The level of leptin was investigated in 167 disease-free volunteers. Serum levels of IL-6, adiponectin, and resistin, blood lipid profile (cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride (TG) were determined. Waist circumference (WC) was measured using tape and magnetic resonance imaging (MRI) images.

RESULTS

All measured anthropometric (BMI, WC measured by tape and MRI) and biochemical variables (adiponectin, resistin, cholesterol, HDL, LDL and TG); and abdominal fats showed a significant (p<0.05) difference between participants with abnormal serum leptin levels and those with normal leptin levels. A higher percentage of participants with abnormal serum leptin were obese males while participants with normal leptin levels were either overweight or normal weight females. A significant (p <0.05) positive correlation was detected between serum leptin concentration and WC, BMI, subcutaneous fat, visceral fat, total abdominal fat, and resistin. A moderate association was found between serum leptin concentration and the inflammatory cytokine IL-6.

CONCLUSION

Abnormal serum leptin, was detected in obese male individuals which may be considered as an important indicator for the development of cardiovascular diseases and type 2 diabetes.

Leptin and Leptin Resistance in the Pathogenesis of Obstructive Sleep Apnea: A Possible Link to Oxidative Stress and Cardiovascular Complications

Obesity-related sleep breathing disorders such as obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS) cause intermittent hypoxia (IH) during sleep, a powerful trigger of oxidative stress. Obesity also leads to dramatic increases in circulating levels of leptin, a hormone produced in adipose tissue. Leptin acts in the hypothalamus to suppress food intake and increase metabolic rate. However, obese individuals are resistant to metabolic effects of leptin. Leptin also activates the sympathetic nervous system without any evidence of resistance, possibly because these effects occur peripherally without a need to penetrate the blood-brain barrier. IH is a potent stimulator of leptin expression and release from adipose tissue. Hyperleptinemia and leptin resistance may upregulate generation of reactive oxygen species, increasing oxidative stress and promoting inflammation. The current review summarizes recent data on a possible link between leptin and oxidative stress in the pathogenesis of sleep breathing disorders.

Association between the circulating leptin levels and the biomarkers of oxidative stress and inflammation among Iranian overweight and obese adults

Background: Oxidative stress in obese people is an important pathogenic mechanism of an obesity-associated metabolic syndrome. We evaluated the association between circulating leptin levels with biomarkers of oxidative stress in overweight and obese participants.

Methods: This study was performed on 189 overweight and obese people aged 18-60 years old. Serum leptin, superoxide dismutase (SOD), high-sensitivity C-reactive protein (hs-CRP), homocysteine (Hcy), thiobarbituric acid reactive substances (TBARS) and amyloid A (SAA) concentrations were measured. Pearson correlation and multiple linear regressions were used to assess the relationships.

Results: We found that among the biomarkers of oxidative stress and inflammation in participants, serum hs-CRP and SAA were positively correlated with BMI (β=0.003, P<0.001 and β=7.83, P<0.001, respectively). This relationship remained significant even after controlling other oxidative stress and inflammatory indicators (β=0.003, p<0.001 for hs-CRP), but this association disappeared for SAA. In addition, serum hs-CRP was positively correlated with leptin (β=0.001, p=0.003). Regression analysis showed that there was no association between serum Hcy, SAA, TBARS and SOD with serum leptin concentrations

Conclusion: Overall, the current study demonstrated that serum hs-CRP and SAA levels were independently correlated with BMI. Furthermore, serum hs-CRP was positively correlated with leptin. Focusing on such strategies may lead to promises for alleviating obesity and its co-morbidities.

Depressive symptoms in patients with obstructive sleep apnea: biological mechanistic pathways

This study examined the association between depressive symptoms, as well as depressive symptom dimensions, and three candidate biological pathways linking them to Obstructive sleep apnea (OSA): (1) inflammation; (2) circulating leptin; and (3) intermittent hypoxemia. Participants included 181 obese adults with moderate-to-severe OSA enrolled in the Cardiovascular Consequences of Sleep Apnea (COSA) trial. Depressive symptoms were measured using the Beck Depression Inventory-II (BDI-II). We assessed inflammation using C-reactive protein levels (CRP), circulating leptin by radioimmunoassay using a double antibody/PEG assay, and intermittent hypoxemia by the percentage of sleep time each patient had below 90% oxyhemoglobin saturation. We found no significant associations between BDI-II total or cognitive scores and CRP, leptin, or percentage of sleep time below 90% oxyhemoglobin saturation after controlling for relevant confounding factors. Somatic symptoms, however, were positively associated with percentage of sleep time below 90% saturation (β = 0.202, P = 0.032), but not with CRP or circulating leptin in adjusted models. Another significant predictor of depressive symptoms included sleep efficiency (β_{BDI Total} = -0.230, P = 0.003; β_cognitive = -0.173, P = 0.030 (β_somatic = -0.255, P = 0.001). In patients with moderate-to-severe OSA, intermittent hypoxia may play a role in somatic rather than cognitive or total depressive symptoms.

The serum leptin level in non-obese patients with obstructive sleep apnea

OBJECTIVE

This study aimed to determine the association between the severity of obstructive sleep apnea (OSA) and the serum leptin level in non-obese OSA patients.

METHODS

This prospective case-control study included non-obese OSA patients that presented with sleep-related disturbances and underwent polysomnography (PSG) between April 2015 and June 2016. The serum leptin level was measured and its relationship to PSG parameters was investigated.

RESULTS

The study included 73 OSA patients (20 female and 53 male) with a mean age of 41.1±11.5 years and mean body-mass index (BMI) of 26.4±2.7kgm^-2. The serum leptin level in 44 patients with moderate/severe OSA (AHI ≥15) was 3.4±2.6ngmL^-1, versus 4.5±3.8ngmL^-1 in 29 patients with snoring/mild OSA (AHI <15) (P=0.20). There were not any correlations between any of the PSG parameters and the serum leptin level, but there was a significant correlation between the leptin level and BMI (r=0.345, P<0.01).

CONCLUSION

The serum leptin level does not differ significantly between non-obese OSA patients with moderate/severe and snoring/mild OSA. Obesity is the primary factor associated with the serum leptin level.

Serum apelin levels and metabolic risk markers in obese women

Background

Adipose tissue hormones, Adipokines, play an important role in obesity-associated complications. Apelin has recently been added to the family of adipokines. The aim of this study was to evaluate the relationship between serum apelin levels and metabolic abnormal parameters in Egyptian obese women.

Materials and methods

The study included 400 unrelated women; they were 200 obese women and 200 non- obese matched healthy women. All participants underwent clinical, anthropometric and biochemical examinations. Insulin resistance (IR) was determined by the homeostasis model assessment of insulin resistance (HOMA-IR). Serum apelin levels and obesity biomarkers were measured using enzyme-linked immunoassay (ELISA) kits. Fat mass was measured by Tanita Body Composition Analyzer.

Results

Obese women showed significant higher levels of serum apelin, leptin, triglycerides, LDL-C, total cholesterol, fasting insulin HOMA-IR and blood pressure levels than controls. Significant positive correlations between apelin and leptin levels with abnormal metabolic markers were noted in obese women.

Conclusion

The present study suggests the significant role that might be mediated by apelin for developing abnormal metabolic parameters among Egyptian obese women.

Possitive correlation between adipocyte fatty acid-binding protein and epicardial fat in patients with a family history of cardiovascular disesase

BACKGROUND

Adipocyte fatty acid-binding protein (A-FABP) is a promising link between metabolic syndrome and atherosclerosis. Epicardial fat (EPI) is an independent risk factor for cardiovascular disease (CVD).

OBJECTIVE

The aim of this pilot study was to evaluate the correlation between EPI and A-FABP in asymptomatic patients with a family history of CVD.

METHODS

59 subjects (39 males) (median = 54 years old) were enrolled in the study and their EPI thickness and A-FABP levels were assessed.

RESULTS

EPI was found in 46 patients (77.9%). There were positive correlations between EPI and A-FABP (r=0.336; P=0.010), age (r=0.526; P<0.001), fibrinogen (r=0.304; P=0.023) and systolic blood pressure (r=0.279; P=0.034). A positive correlation was found between EPI and A-FABP in a subgroup of overweight and obese patients (0.389; P=0.041, 0.407; P=0.004) and in the subgroup of patients with excluded CVD (r=0.368; P=0.006).

CONCLUSIONS

We found a positive correlation between EPI and A-FABP in a group of patients with a family history of CVD and in subgroups of overweight and obese patients.

The relationship between sleep apnea, metabolic dysfunction and inflammation: The gender influence

Obstructive sleep apnea (OSA) has been associated with increased risk of cardiovascular morbidity and mortality. Although inflammatory markers may mediate this association, it is unknown the influence of gender in this mechanism. Thus, we aimed to evaluate the interaction effects between OSA and gender on metabolic and inflammatory profile in a population sample. This study is part of EPISONO cohort, in which 1042 participants underwent polysomnography, answered questionnaires, and had their blood collected for analysis of fasting glucose, total cholesterol and fractions, leptin, ghrelin, liver transaminases, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and C-reactive protein. The results showed that men with OSA had higher leptin levels, shorter sleep latency and lower N3 sleep stage compared to men control (CTRL). They also presented higher apnea index and number of central apneas compared to both CTRL men and OSA women. In women, OSA was related to longer REM sleep latency, higher apnea-hypopnea index (AHI) during REM sleep and increased TNF-α levels compared to CTRL women. A multivariate model showed that male gender, ghrelin and total cholesterol were negatively associated with TNF-α, while IL-6, triglycerides and hypopnea index were positively associated (R²=0.21). Additionally, gender (men), body mass index, ghrelin, apnea index and smoking were positive predictors of leptin levels (R²=0.55). Of note, postmenopause was associated with changes observed in both TNF-α and AHI during REM sleep in women with OSA. Taken together, our study suggests that OSA consequences may differ between genders and this could indicate a need for different OSA management in women according to their reproductive life's stage.

Insomnia complaints in lean patients with obstructive sleep apnea negatively affect positive airway pressure treatment adherence

The objective of this study was to evaluate the determinants of long-term adherence to positive airway pressure treatment among patients with obstructive sleep apnea, with special emphasis on patients who stop positive airway pressure treatment within 1 year. This is a prospective long-term follow-up of subjects in the Icelandic Sleep Apnea Cohort who were diagnosed with obstructive sleep apnea between 2005 and 2009, and started on positive airway pressure treatment. In October 2014, positive airway pressure adherence was obtained by systematically evaluating available clinical files (n = 796; 644 males, 152 females) with moderate to severe obstructive sleep apnea (apnea-hypopnea index ≥15 events per h). The mean follow-up time was 6.7 ± 1.2 years. In total, 123 subjects (15.5%) returned their positive airway pressure device within the first year, 170 (21.4%) returned it later and 503 (63.2%) were still using positive airway pressure. The quitters within the first year had lower body mass index, milder obstructive sleep apnea, less sleepiness, and more often had symptoms of initial and late insomnia compared with long-term positive airway pressure users at baseline. Both initial and late insomnia were after adjustment still significantly associated with being an early quitter among subjects with body mass index <30 kg m^-2 , but not among those with body mass index ≥30 kg m^-2 . The prevalence of early quitters decreased significantly during the study period (2005-2009). Almost two-thirds of patients with moderate to severe obstructive sleep apnea are positive airway pressure users after 7 years. Obesity level, obstructive sleep apnea severity and daytime sleepiness are important determinants of long-term adherence. Symptoms of initial and late insomnia are associated with early quitting on positive airway pressure among non-obese subjects.

Obesity as a risk factor for malignant melanoma and non-melanoma skin cancer

The dramatic increases in incidence of both obesity and many cancers including skin cancer emphasize the need to better understand the pathophysiology of both conditions and their connections. Melanoma is considered the fastest growing cancer and rates of non-melanoma skin cancer have also increased over the last decade. The molecular mechanisms underlying the association between obesity and skin cancer are not clearly understood but emerging evidence points to changes in the tumor microenvironment including aberrant cell signaling and genomic instability in the chronic inflammatory state many obese individuals experience. This article reviews the literature linking obesity to melanoma and non-melanoma skin cancer.

Relationship between leptin concentration and body fat with peripheral blood mononuclear cells cytokines among obese and overweight adults

BACKGROUND

Overweight and obesity has been suggested to be well correlated with altered levels of pro-inflammatory cytokines.

AIM

The purpose of this study is to assess the relationship of body fat mass (BFM), body fat percentage (BFP) and leptin levels with peripheral blood mononuclear cells (PBMCs) cytokines among obese and overweight adults.

METHODS

Eighty-two overweight and obese individuals were divided into two BMI-category groups (BMI <30 and BMI ≥30 kg/m²) in this study. Balanced blocked randomization was used based on their sex and BMI ranges. Fasting blood samples, PBMCs cytokines, leptin and anthropometric indices were measured and PBMCs were cultured.

RESULTS

Mean of leptin concentrations were 23.14 ± 4.07 and 28.25 ± 4.35 pg/ml among individuals with BMI <30 and BMI ≥30 kg/m², respectively. The mean values of anthropometric measurements (all P < 0.001), the concentrations of TNF-α (P = 0.028) and IFN-γ (P = 0.029) were significantly higher among obese individuals. BFP had a significant positive correlation with leptin (P < 0.001, r = 0.445) and TGF-β (P = 0.03, r = 0.243). BFM has significant positive correlation with leptin (P < 0.001, r = 0.521). Leptin had a positive significant correlation with IFN-γ (p = 0.03, r = 0.251).

CONCLUSIONS

Regarding these results, we proved that BFP, BFM and leptin levels have significant correlations with some PBMC cytokines. Focusing on such strategies may lead to promises for alleviating obesity and its co-morbidities.

Leptin level correlates with obesity and health related quality of life in obstructive sleep apnea syndrome patients

BACKGROUND

Leptin takes part in regulation of energy balance, neuronal functions, pain and mood. It may act as intermediary marker for various components of HRQOL in patients of obstructive sleep apnea syndrome.

AIMS

To document the correlation among leptin levels, obesity and HRQoL in OSAS patients.

METHODS

A tertiary care hospital based cross-sectional study was done in 224 subjects aged 18-65 years, after taking informed consent. Subjects with previous history of smoking, Liver disease, COPD, CHD, T2 DM, asthma, cancer, end stage renal disease, heart failure, any endocrine disorder including Cushing syndrome, thyroid, on systemic steroid or any continuous medication for last 6 months, on dieting or suffering from any disability condition (other than obesity and OSAS) affecting their HRQoL were excluded from the study. All subjects underwent Polysomnography. Leptin assay was done by ELISA method. Hindi version of HRQoL tool SF-36 was used to evaluate HRQoL.

RESULTS

SPSS 20 was used to analyse data. Three groups (AHI <5, 5 to 15 and >15) were compared. Significant differences were observed in BMI, NC, WC, WHR and ESS. Differences were not significant in sleep architecture and Leptin level. SF-36 HRQoL, scores were observed decreased with increase in severity of disease. Leptin level was found significantly correlated with "Role limitations due to physical health problems", "Social functioning", Hypopnea and obesity indices.

CONCLUSIONS

In these subjects Obesity indices are the most important correlates of Leptin level. Oxygen desaturation indices with exception of Hypopnea and HRQoL may not be exclusively correlated to leptin levels.

Obstructive sleep apnoea, insulin resistance and adipocytokines

Obstructive sleep apnoea (OSA) is associated with multiple cardiometabolic abnormalities. Obesity is considered a major risk factor for the development of OSA, and it is also an established risk factor for insulin resistance and other cardiometabolic disorders. The enigma remains whether OSA has any causal role in the adverse metabolic profile, independent of or beyond that due to obesity. Sleep apnoeas and hypopnoeas result directly in intermittent hypoxaemia and cerebral arousals, both of which may evoke a cascade of downstream biologic responses in various body tissues and cells. Adipose tissue is a major source of adipocytokines many of which play important roles in the regulation of various metabolic functions. It is hypothesized that OSA may, through its unique pathophysiology, affect metabolic function through modulation of production or action of adipocytokines. This review focuses on insulin resistance, glucose metabolism and relevant adipocytokines in the context of OSA.

Intermittent hypoxia and diet-induced obesity: effects on oxidative status, sympathetic tone, plasma glucose and insulin levels, and arterial pressure

Obstructive sleep apnea (OSA) consists of sleep-related repetitive obstructions of upper airways that generate episodes of recurrent or intermittent hypoxia (IH). OSA commonly generates cardiovascular and metabolic pathologies defining the obstructive sleep apnea syndrome (OSAS). Literature usually links OSA-associated pathologies to IH episodes that would cause an oxidative status and a carotid body-mediated sympathetic hyperactivity. Because cardiovascular and metabolic pathologies in obese patients and those with OSAS are analogous, we used models (24-wk-old Wistar rats) of IH (applied from weeks 22 to 24) and diet-induced obesity (O; animals fed a high-fat diet from weeks 12 to 24) to define the effect of each individual maneuver and their combination on the oxidative status and sympathetic tone of animals, and to quantify cardiovascular and metabolic parameters and their deviation from normality. We found that IH and O cause an oxidative status (increased lipid peroxides and diminished activities of superoxide dismutases), an inflammatory status (augmented C-reactive protein and nuclear factor kappa-B activation), and sympathetic hyperactivity (augmented plasma and renal artery catecholamine levels and synthesis rate); combined treatments worsened those alterations. IH and O augmented liver lipid content and plasma cholesterol, triglycerides, leptin, glycemia, insulin levels, and HOMA index, and caused hypertension; most of these parameters were aggravated when IH and O were combined. IH diminished ventilatory response to hypoxia, and hypercapnia and O created a restrictive ventilatory pattern; a combination of treatments led to restrictive hypoventilation. Data demonstrate that IH and O cause comparable metabolic and cardiovascular pathologies via misregulation of the redox status and sympathetic hyperactivity.

The different clinical faces of obstructive sleep apnoea: a cluster analysis

Although commonly observed in clinical practice, the heterogeneity of obstructive sleep apnoea (OSA) clinical presentation has not been formally characterised. This study was the first to apply cluster analysis to identify subtypes of patients with OSA who experience distinct combinations of symptoms and comorbidities. An analysis of baseline data from the Icelandic Sleep Apnoea Cohort (822 patients with newly diagnosed moderate-to-severe OSA) was performed. Three distinct clusters were identified. They were classified as the "disturbed sleep group" (cluster 1), "minimally symptomatic group" (cluster 2) and "excessive daytime sleepiness group" (cluster 3), consisting of 32.7%, 24.7% and 42.6% of the entire cohort, respectively. The probabilities of having comorbid hypertension and cardiovascular disease were highest in cluster 2 but lowest in cluster 3. The clusters did not differ significantly in terms of sex, body mass index or apnoea-hypopnoea index. Patients with OSA have different patterns of clinical presentation, which need to be communicated to both the lay public and the professional community with the goal of facilitating care-seeking and early identification of OSA. Identifying distinct clinical profiles of OSA creates a foundation for offering more personalised therapies in the future.

Obstructive sleep apnoea treatment and fasting lipids: a comparative effectiveness study

Obstructive sleep apnoea (OSA) is associated with cardiovascular disease. Dyslipidaemia has been implicated as a mechanism linking OSA with atherosclerosis, but no consistent associations with lipids exist for OSA or positive airway pressure treatment. We assessed the relationships between fasting lipid levels and obesity and OSA severity, and explored the impact of positive airway pressure treatment on 2-year fasting lipid level changes. Analyses included moderate-to-severe OSA patients from the Icelandic Sleep Apnoea Cohort. Fasting morning lipids were analysed in 613 untreated participants not on lipid-lowering medications at baseline. Patients were then initiated on positive airway pressure and followed for 2 years. Sub-classification using propensity score quintiles, which aimed to replicate covariate balance associated with randomised trials and, therefore, minimise selection bias and allow causal inference, was used to design the treatment group comparisons. 199 positive airway pressure adherent patients and 118 non-users were identified. At baseline, obesity was positively correlated with triglycerides and negatively correlated with total cholesterol, and low-density and high-density lipoprotein cholesterol. A small correlation was observed between the apnoea/hypopnoea index and high-density lipoprotein cholesterol. No effect of positive airway pressure adherence on 2-year fasting lipid changes was observed. Results do not support the concept of changes in fasting lipids as a primary mechanism for the increased risk of atherosclerotic cardiovascular disease in OSA.

The influence of obesity on different genders in patients with obstructive sleep apnea

Obesity is considered to be a major contributing factor to obstructive sleep apnea (OSA); however, there is limited evidence with regard to gender predominance. We analyzed 2345 patients (339 females) in correlation with body mass index (BMI) and OSA severity. Male AHIs were significantly higher than female AHIs in each BMI group. As the BMI increased, the AHI increased in both males and females, and this trend was more obvious in males. For BMI-matched male and female patients with OSA, the severity of OSA was higher in males. As BMI increased, the severity of OSA increased more obviously in males. Our findings suggest that increased body fat contributes to the pathogenesis of OSA more in males than in females and that obesity plays a more significant role in contributing to OSA in male patients.

Facial phenotyping by quantitative photography reflects craniofacial morphology measured on magnetic resonance imaging in Icelandic sleep apnea patients

STUDY OBJECTIVES

(1) To determine whether facial phenotype, measured by quantitative photography, relates to underlying craniofacial obstructive sleep apnea (OSA) risk factors, measured with magnetic resonance imaging (MRI); (2) To assess whether these associations are independent of body size and obesity.

DESIGN

Cross-sectional cohort.

SETTING

Landspitali, The National University Hospital, Iceland.

PARTICIPANTS

One hundred forty patients (87.1% male) from the Icelandic Sleep Apnea Cohort who had both calibrated frontal and profile craniofacial photographs and upper airway MRI. Mean ± standard deviation age 56.1 ± 10.4 y, body mass index 33.5 ± 5.05 kg/m(2), with on-average severe OSA (apnea-hypopnea index 45.4 ± 19.7 h(-1)).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Relationships between surface facial dimensions (photos) and facial bony dimensions and upper airway soft-tissue volumes (MRI) was assessed using canonical correlation analysis. Photo and MRI craniofacial datasets related in four significant canonical correlations, primarily driven by measurements of (1) maxillary-mandibular relationship (r = 0.8, P < 0.0001), (2) lower face height (r = 0.76, P < 0.0001), (3) mandibular length (r = 0.67, P < 0.0001), and (4) tongue volume (r = 0.52, P = 0.01). Correlations 1, 2, and 3 were unchanged when controlled for weight and neck and waist circumference. However, tongue volume was no longer significant, suggesting facial dimensions relate to tongue volume as a result of obesity.

CONCLUSIONS

Significant associations were found between craniofacial variable sets from facial photography and MRI. This study confirms that facial photographic phenotype reflects underlying aspects of craniofacial skeletal abnormalities associated with OSA. Therefore, facial photographic phenotyping may be a useful tool to assess intermediate phenotypes for OSA, particularly in large-scale studies.

Nocturnal sweating--a common symptom of obstructive sleep apnoea: the Icelandic sleep apnoea cohort

OBJECTIVES

To estimate the prevalence and characteristics of frequent nocturnal sweating in obstructive sleep apnoea (OSA) patients compared with the general population and evaluate the possible changes with positive airway pressure (PAP) treatment. Nocturnal sweating can be very bothersome to the patient and bed partner.

DESIGN

Case-control and longitudinal cohort study.

SETTING

Landspitali-The National University Hospital, Iceland.

PARTICIPANTS

The Icelandic Sleep Apnea Cohort consisted of 822 untreated patients with OSA, referred for treatment with PAP. Of these, 700 patients were also assessed at a 2-year follow-up. The control group consisted of 703 randomly selected subjects from the general population.

INTERVENTION

PAP therapy in the OSA cohort.

MAIN OUTCOME MEASURES

Subjective reporting of nocturnal sweating on a frequency scale of 1-5: (1) never or very seldom, (2) less than once a week, (3) once to twice a week, (4) 3-5 times a week and (5) every night or almost every night. Full PAP treatment was defined objectively as the use for ≥4 h/day and ≥5 days/week.

RESULTS

Frequent nocturnal sweating (≥3× a week) was reported by 30.6% of male and 33.3% of female OSA patients compared with 9.3% of men and 12.4% of women in the general population (p<0.001). This difference remained significant after adjustment for demographic factors. Nocturnal sweating was related to younger age, cardiovascular disease, hypertension, sleepiness and insomnia symptoms. The prevalence of frequent nocturnal sweating decreased with full PAP treatment (from 33.2% to 11.5%, p<0.003 compared with the change in non-users).

CONCLUSIONS

The prevalence of frequent nocturnal sweating was threefold higher in untreated OSA patients than in the general population and decreased to general population levels with successful PAP therapy. Practitioners should consider the possibility of OSA in their patients who complain of nocturnal sweating.