Recent weight gain in patients with newly diagnosed obstructive sleep apnea.

OBJECTIVE: Patients with obstructive sleep apnea are often obese. Obesity may contribute to both sleep apnea itself and to the cardiovascular risk associated with sleep apnea. Weight loss in obese patients with sleep apnea may alleviate symptoms and decrease the severity of sleep apnea. Whether patients with obstructive sleep apnea are indeed predisposed to recent weight gain, as compared with similarly obese subjects without sleep apnea, is not known. PATIENTS AND METHODS: We compared 1-year weight histories in 53 male and female patients newly diagnosed with obstructive sleep apnea, compared with 24 controls matched for gender, age, body mass index, and percent body fat. Sleep apnea patients had never been treated. Control subjects were proven to be free of sleep-disordered breathing by overnight polysomnography. RESULTS: Patients with obstructive sleep apnea (n = 53) had a significant recent weight gain of 7.4 +/- 1.5 kg compared with a weight loss of 0.5 +/- 1.7 kg (P = 0.001) in similarly obese controls (n = 24). Male patients with obstructive sleep apnea (n = 28) had a history of significant weight gain (6.8 +/- 2.3 kg) over the year preceding the study compared with male control subjects (n = 13), in whom average weight fell by 0.58 +/- 2.4 kg (P = 0.03). Female patients (n = 25) with obstructive sleep apnea had an 8.0 +/- 1.9 kg weight gain compared with female controls (n = 11) who had a history of weight loss of 0.46 +/- 2.6 kg (P = 0.02). CONCLUSION: These findings support the concept that patients with obstructive sleep apnea may be susceptible to increasing obesity in the period preceding the diagnosis of obstructive sleep apnea.     

Altered blood rheology in obstructive sleep apnea as a mediator of cardiovascular risk

BACKGROUND: Cardiovascular complications are common in patients with obstructive sleep apnea (OSA). Blood rheology is a major determent of coagulation and an established risk factor for cardiovascular events. Since nocturnal hypoxemia could influence parameters of blood rheology, we hypothesized that OSA alters blood rheology independent of other cardiovascular risk factors. METHODS: One hundred and ten consecutive patients admitted to the sleep laboratory were included. The association of plasma fibrinogen and viscosity (as parameters of blood rheology) with OSA was evaluated. RESULTS: One hundred and ten patients aged 61.4+/-10.1 years (body mass index 28.4+/-4.1 kg/m2) were included. OSA was confirmed in 63 patients (57.2%) with an apnea-hypopnea index (AHI) of 28.7+/-14.9 events/hour. Patients with OSA showed higher levels of plasma viscosity (1.36+/-0.09 vs. 1.31+/-0.08 mPas, p=0.005). Nevertheless, hypertensive apneics have even higher levels of plasma viscosity than nonapneics (1.38+/-0.091 vs. 1.32+/-0.028 mPas, p=0.018). Similar results were found in patients with coronary artery disease, where OSA was associated with elevated plasma viscosity (1.36+/-0.076 vs. 1.31+/-0.081 mPas, p=0.007). Plasma fibrinogen was correlated with nocturnal minimal oxygen saturation (r=-0275, p=0.0036) and AHI (r=0.297, p=0.001). OSA was associated with higher plasma fibrinogen (353+/-83 vs. 317+/-62 mg/dl, p=0.015). These differences persist with control for cardiovascular risk factors. CONCLUSIONS: Patients with OSA have elevated morning fibrinogen levels and a higher plasma viscosity, which correlate positively with indices of sleep apnea severity. These changes in blood rheology are independent of cardiovascular risk factors, and therefore, might be specific mechanisms of OSA. This supports the pathophysiological concept that sleep apnea is a cardiovascular risk factor.     

The impact of body mass index on later total hip arthroplasty for primary osteoarthritis: a cohort study in 1.2 million persons

OBJECTIVE: To investigate the effects of body mass index (BMI), height, and age on the risk of later total hip arthroplasty for primary osteoarthritis (OA). METHODS: We matched screening data on body height and weight from 1,152,006 persons ages 18-67 years who attended a compulsory screening for tuberculosis in 1963-1975 with data from the Norwegian Arthroplasty Register for the years 1987-2003. We identified 28,425 total hip replacements because of primary OA. RESULTS: We found dose-response associations between both height and BMI and later hip arthroplasty. The relative risk (RR) among men with a BMI > or = 32 kg/m2 versus a BMI of 20.5-21.9 kg/m2 was 3.4 (95% confidence interval [95% CI] 2.9-4.0). The corresponding RR in women was 2.3 (95% CI 2.1-2.4). There was a decreasing trend in the RR with an increasing age at screening. Among men, the RR for an increase of 5 kg/m2 in the BMI was 2.1 (95% CI 1.7-2.5) when measured at age <25 years and 1.5 (95% CI 1.3-1.7) when measured at ages 55-59 years. Among women, the corresponding RR values were 1.7 (95% CI 1.5-1.9) and 1.1 (95% CI 1.1-1.2). CONCLUSION: There was a strong dose-response association between BMI and later total arthroplasty for OA of the hip. Being overweight entailed the highest RR among young participants, and the participants who were overweight at a young age maintained an excess RR for arthroplasty throughout the followup period.     

Obstructive sleep apnea is a risk factor for death in patients with stroke: a 10-year follow-up

BACKGROUND: Sleep apnea occurs frequently among patients with stroke, but it is still unknown whether a diagnosis of sleep apnea is an independent risk factor for mortality. We aimed to investigate whether obstructive or central sleep apnea was related to reduced long-term survival among patients with stroke. METHODS: Of 151 patients admitted for in-hospital stroke rehabilitation in the catchment area of Ume? from April 1, 1995, to May 1, 1997, 132 underwent overnight sleep apnea recordings at a mean (SD) of 23 (8) days after the onset of stroke. All patients were followed up prospectively for a mean (SD) of 10.0 (0.6) years, with death as the primary outcome; no one was lost to follow-up. Obstructive sleep apnea was defined when the obstructive apnea-hypopnea index was 15 or greater, and central sleep apnea was defined when the central apnea-hypopnea index was 15 or greater. Patients with obstructive and central apnea-hypopnea indexes of less than 15 served as control subjects. RESULTS: Of 132 enrolled patients, 116 had died at follow-up. The risk of death was higher among the 23 patients with obstructive sleep apnea than controls (adjusted hazard ratio, 1.76; 95% confidence interval, 1.05-2.95; P = .03), independent of age, sex, body mass index, smoking, hypertension, diabetes mellitus, atrial fibrillation, Mini-Mental State Examination score, and Barthel index of activities of daily living. There was no difference in mortality between the 28 patients with central sleep apnea and controls (adjusted hazard ratio, 1.07; 95% confidence interval, 0.65-1.76; P = .80). CONCLUSIONS: Patients with stroke and obstructive sleep apnea have an increased risk of early death. Central sleep apnea was not related to early death among the present patients.     

Effect of continuous positive airway pressure on the risk of road accidents in sleep apnea patients

BACKGROUND: Continuous positive airway pressure (CPAP) reduces daytime somnolence in the obstructive sleep apnea syndrome (OSAS) and may contribute to a reduction in the risk of motor vehicle accidents. OBJECTIVE: To evaluate the effects of CPAP on automobile collisions in patients with OSAS. METHODS: We compared the number of motor vehicle accidents in 80 patients with OSAS and 80 healthy subjects during the 2 years before and the 2 years after study entry, at which CPAP treatment was initiated. RESULTS: Patients with OSAS had a 2.6 times higher risk of suffering an automobile collision compared to controls (rate ratio, RR=2.57; 95% confidence interval, CI=1.30-5.05). After 2 years of CPAP treatment, the rate of collisions was reduced more than half in patients with OSAS (RR=0.41; 95% CI=0.21-0.79), but this occurred also in controls (RR=0.49; 95% CI=0.17-1.40). The magnitude of this fall between groups was not different (p for interaction=0.68), even after adjusting for body mass index, alcohol intake and Epworth scale. CONCLUSIONS: Patients with OSAS have an increased risk of suffering a traffic collision. This risk was significantly reduced after their inclusion in the study. Yet, as this reduction also occurred in the control group, this effect may not be due to CPAP therapy.     

Obstructive sleep apnea-dependent and -independent adrenergic activation in obesity

No agreement exists as to the mechanisms responsible for the sympathetic hyperactivity characterizing human obesity, which has been ascribed recently to a chemoreflex stimulation brought about by obstructive sleep apnea rather than to an increase in body weight, per se. In 86 middle-age normotensive subjects classified according to body mass index, waist-to-hip ratio, and apnea/hypopnea index (overnight polysomnographic evaluation) as lean and obese subjects without or with obstructive sleep apnea, we assessed via microneurography muscle sympathetic nerve traffic. The 4 groups were matched for age, gender, and blood pressure values, the 2 obese groups with and without obstructive sleep apnea showing a similar increase in body mass index (32.4 versus 32.0 kg/m2, respectively) and waist-to-hip ratio (0.96 versus 0.95, respectively) compared with the 2 lean groups with or without obstructive sleep apnea (body mass index 24.3 versus 23.8 kg/m2 and waist-to-hip ratio 0.77 versus 0.76, respectively; P<0.01). Compared with the nonobstructive sleep apnea lean group, muscle sympathetic nerve activity showed a similar increase in the obstructive sleep apnea lean group and in the nonobstructive sleep apnea obese group (60.4+/-2.3 and 59.3+/-2.0 versus 40.9+/-1.8 bs/100 hb, respectively; P<0.01), a further increase being detected in obstructive sleep apnea subjects (73.1+/-2.5 bursts/100 heart beats; P<0.01). Our data demonstrate that the sympathetic activation of obesity occurs independently in obstructive sleep apnea. They also show that this condition exerts sympathostimulating effects independent of body weight, and that the obstructive sleep apnea-dependent and -independent sympathostimulation contribute to the overall adrenergic activation of the obese state.     

Obesity: A Risk Factor for Severe Acute Biliary and Alcoholic Pancreatitis

Objective: In this study we evaluate the association between obesity and complication development in patients with a first-attack acute pancreatitis (AP), and investigate the influence of comorbid factors on this association.
Methods: Medical records of 150 patients with AP were reviewed. General data, AP etiology, admission AP prognostic criteria, and occurrence of complications were recorded. Patients were classified according to body mass index (BMI) as obese (  BMI > 25  kg/m²) and nonobese (  BMI ≤ 25  kg/m²).
Results: Prevalence of obesity was 57%. Thirty-eight percent of the obese patients developed complications as compared with 21% of the nonobese (  RR = 1.74  ; 95% CI, 1–2.9). The risk for severe AP increased according to the degree of obesity. Pancreatic and peripancreatic necrosis was more common in obese patients (17.6% vs 6%), as was the incidence of infectious complications. The risk for severe AP was highest in obese patients with either alcoholic (  RR = 5.3  ; 95% CI, 1.2–23) or biliary etiology (  RR = 5.2  , 95% CI, 1–26).
Conclusion: Obesity may predispose to a complicated course of AP, especially if it is secondary to alcohol or gallstones. Further studies are needed to establish the precise prognostic value of obesity in AP, as well as the pathogenic mechanisms involved in the process.     

Sleep Apnea Syndrome in a Referral Population in Greece: Influence of Social Factors

Objective The aim of this work was to study whether social factors are risk factors for obstructive sleep apnea (OSA). A second objective was to investigate gender differences in relation to referral to a sleep laboratory for sleep-related breathing symptoms. Study Design A retrospective cross-sectional study was conducted in the referral sleep disorders laboratory in the tertiary University Hospital in Patras in southwest Greece. A sample of 362 subjects originated from this geographic region was screened for social characteristics, i.e., marital status, occupation, and education. Results The apnea hypopnea index (AHI) was approximately three times as high in men as in women (p < 0.05). Snoring was reported to be a symptom by 76.6% of males and 75% of females. Excessive daytime sleepiness (EDS) was reported by 25.5% of males and 15% of females. Arousals during sleep were reported by 5.7% of men and 10% of women. The ratio of subjects with concomitant disorders or symptoms did not differ between sexes (p > 0.05). The influence of age, body mass index (BMI), gender, smoking, and social characteristics on AHI was examined by multinomial logistic regression. The following factors remained independent risk factors for the presence of moderate to severe OSA (i.e., AHI > 15/h compared with AHI < 5): (1) Gender: the odds ratio (OR) of males to females was 6.23 (CI = 1.89–20.5). (2) Obesity: the OR of subjects with BMI >30.5 kg/m² in comparison to those with lower BMI was 3.83 (CI = 1.86–7.86). (3) Marital status: The OR of married subjects to singles was 2.30 (CI = 1.01–5.32). (4) Occupational status: The OR of subjects outside the work force was 3.85 (CI = 1.16–12.74) and that of the self-employed was 1.70 (CI = 0.70–4.10) compared to a reference group of clerks/employees. Conclusion In our study factors associated with the presence of sleep apnea include gender (men), obesity, marriage, and self-employment or being outside the work force.     

Prevalence and correlates of sleep-disordered breathing in older men: osteoporotic fractures in men sleep study

OBJECTIVES: To determine the prevalence and distribution of sleep-disordered breathing and associated correlates in a large cohort of older men using several standardized definitions. DESIGN: Cross-sectional analyses. SETTING: Six U.S. communities. PARTICIPANTS: Polysomnography was performed on 2,911 participants of the Outcomes of Sleep Disorders in Older Men Sleep Study (mean age+/-standard deviation 76.38+/-5.53; body mass index 27.17+/-3.8 kg/m(2)). MEASUREMENTS: Three outcomes were assessed: sleep-disordered breathing (respiratory disturbance index > or =15), obstructive apnea (obstructive apnea index > or =5), and central apnea (central apnea index > or =5). RESULTS: The prevalence of moderate-severe sleep-disordered breathing was estimated to be 21.4% to 26.4%. Multivariable logistic regression models demonstrated that age (adjusted odds ratio (AOR) per 5-year increase =1.24, 95% confidence interval (CI)=1.15-1.34), obesity (AOR=2.54, 95% CI=2.09-3.09), Asian versus Caucasian race (AOR=2.14, 95% CI=1.33-3.45), snoring (AOR=2.01, 95% CI=1.62-2.49), sleepiness (AOR=1.41, 95% CI=1.11-1.79), hypertension (AOR=1.26, 95% CI=1.06-1.50), cardiovascular disease (AOR=1.24, 95% CI=1.19-1.29), and heart failure (AOR=1.81, 1.31-2.51) were independently associated with sleep-disordered breathing; snoring (AOR=2.10, 95% CI=1.67-2.70), age (AOR per 5-year increase=1.27, 95% CI=1.18-1.38), obesity (AOR=1.48, 95% CI=1.21-1.82), and heart failure (AOR=1.60, 95% CI=1.15-2.24) were associated with obstructive apnea; and age (AOR=1.33, 1.17-1.50) and heart failure (AOR=1.88, 95% CI=1.17-3.04) were associated with central apnea. CONCLUSION: Regardless of definition, a high prevalence of sleep disorders is observed in community-dwelling older men. Qualitatively similar associations were observed between sleep disorders and snoring, obesity, and comorbidities, as reported for middle aged populations. Asian race was associated with sleep-disordered breathing.     

Reduction of sleep-disordered breathing after physostigmine

The cholinesterase inhibitor physostigmine (PHYS) was investigated in a double-blind, placebo-controlled, randomized, crossover trial of 10 male patients with moderate to severe obstructive sleep apnea. PHYS (0.12 microg/minute/kg, 7-hour infusion) reduced mean apnea/hypopnea index (AHI) by 13.6 (95% confidence interval [CI], 2.2-25.1) corresponding to 21.4% (95% CI, -5.5 to 47.9) and increased minimum SaO2 by 8.7% (95% CI, -0.3 to 17.7) corresponding to 23.2% (95% CI, 4.8-41.3). During the last third of the night, coinciding with predicted plasma concentration steady state, non-REM sleep AHI decreased by 19.2 (95% CI, 0.1-38.3) or 14.9% (95% CI, -43.6 to 77.7) and REM AHI by 33.8 (95% CI, 13.7-54.0) or 67.5% (95% CI, 49.7-85.3). Mean total sleep time was reduced by 74 minutes (95% CI, 33.9-114.9), but patients with the least pronounced sleep shortening had the largest reduction of AHI (r = 0.73, p < 0.02). The nocturnal decline in heart rate was reduced by PHYS. Moreover, resting (early-night placebo heart rate) was positively correlated with proportional reduction of REM apnea index (r = 0.69, p < 0.02). Body mass index was negatively correlated with reduction of REM AHI (r = 0.77, p < 0.02). This, predominantly REM-related, reduction of obstructive sleep apnea after PHYS may provide a new treatment option if the effects are maintained in long-term studies.     

Association of Sleep Apnea Severity and Obesity with Insulin Resistance,C-Reactive Protein,and Leptin Levels in Male Patients with Obstructive Sleep Apnea

Obesity is the major confounding factor in the relationship between obstructive sleep apnea and increased risk for cardiovascular disease. The aim of the study was to investigate the association of sleep apnea severity with insulin resistance, leptin, and CRP levels in a cohort of male patients. Sixty-seven men referred to our sleep laboratory for evaluation of suspected obstructive sleep apnea syndrome (OSAS) were divided into three groups according to apnea severity: non-OSAS group (n=15), mild to moderate OSAS group (n=26), and severe OSAS (n=26). Insulin resistance was estimated by the homeostasis model assessment method. HOMA values were similar in the three groups: (3.2+/-2.2 vs. 3.3+/-1.8 vs. 3.6+/-1.5, respectively, p=0.71). Leptin levels were higher in the mild to moderate OSAS group (23.1+/-21.8 ng/ml, p<0.05) and in the severe OSAS group (20.2+/-17.5 ng/ml, p<0.05) than in the non-OSAS group (9.4+/-6.4 ng/ml). CRP levels were significantly higher in severe sleep apnea (0.35+/-0.3 vs. 0.19+/-0.1 mg/dl, p<0.05). In multiple regression analyses, waist-to-hip ratio (WHR) was the most significant determinant of HOMA estimation for insulin resistance. WHR and the percentage of total sleep time spent with hypoxemia (%TST with SaO2 <90%) were significant predictors for leptin levels, while body mass index (BMI) and the %TST with SaO2 <90% were the best predicting parameters for CRP levels. Insulin resistance estimated by the HOMA method in male patients with OSAS was not associated with sleep apnea severity independent of obesity. The severity of nocturnal hypoxemia was associated with leptin and CRP levels independent of obesity.     

Relationship between plasma lipids and all-cause mortality in nondemented elderly

OBJECTIVES: To investigate the relationship between plasma lipids and risk of death from all causes in nondemented elderly. DESIGN: Prospective cohort study. SETTING: Community-based sample of Medicare recipients, aged 65 years and older, residing in northern Manhattan. PARTICIPANTS: Two thousand two hundred seventy-seven nondemented elderly, aged 65 to 98; 672 (29.5%) white/non-Hispanic, 699 (30.7%) black/non-Hispanic, 876 (38.5%) Hispanic, and 30 (1.3%) other. MEASUREMENTS: Anthropometric measures: fasting plasma total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and non-HDL-C, body mass index, and apolipoprotein E (APOE) genotype. clinical measures: neuropsychological, neurological, medical, and functional assessments; medical history of diabetes mellitus, heart disease, hypertension, stroke, and treatment with lipid-lowering drugs. Vital status measure: National Death Index date of death. Survival methods were used to examine the relationship between plasma lipids and subsequent mortality in younger and older nondemented elderly, adjusting for potential confounders. RESULTS: Nondemented elderly with levels of total cholesterol, non-HDL-C, and LDL-C in the lowest quartile were approximately twice as likely to die as those in the highest quartile (rate ratio (RR)=1.8, 95% confidence interval (CI)=1.3-2.4). These results did not vary when analyses were adjusted for body mass index, APOE genotype, diabetes mellitus, heart disease, hypertension, stroke, diagnosis of cancer, current smoking status, or demographic variables. The association between lipid levels and risk of death was attenuated when subjects with less than 1 year of follow-up were excluded (RR=1.4, 95% CI=1.0-2.1). The relationship between total cholesterol, non-HDL-C, HDL-C, and triglycerides and risk of death did not differ for older (>or=75) and younger participants (>75), whereas the relationship between LDL-C and risk of death was stronger in younger than older participants (RR=2.4, 95% CI=1.2-4.9 vs RR=1.6, 95% CI=1.02-2.6, respectively). Overall, women had higher mean lipid levels than men and lower mortality risk, but the risk of death was comparable for men and women with comparable low lipid levels. CONCLUSION: Low cholesterol level is a robust predictor of mortality in the nondemented elderly and may be a surrogate of frailty or subclinical disease. More research is needed to understand these associations.     

The effects of continuous positive airway pressure on prehypertension and masked hypertension in men with severe obstructive sleep apnea

Obstructive sleep apnea and hypertension are common conditions that frequently coexist. Continuous positive airway pressure (CPAP) reduces blood pressure in patients with obstructive sleep apnea and sustained hypertension. However, the impact of CPAP on patients with obstructive sleep apnea and prehypertension and masked hypertension, conditions associated with increased cardiovascular risk, is unknown. Thirty-six male patients (age, 43 ± 7 years; body mass index, 28.8 ± 3.0 kg/m(2)) with untreated severe obstructive sleep apnea (apnea-hypopnea index, 56 ± 22 events/hr on polysomnography) with diagnostic criteria for prehypertension and/or masked hypertension, based on office and 24-hour ambulatory blood pressure monitoring, respectively, were studied. The patients randomized to no treatment (control; n=18) or CPAP (n=18) for 3 months had similar frequency of prehypertension and masked hypertension at study entry. There were no significant changes in blood pressure in patients randomized to the control group. In contrast, patients randomized to CPAP presented significant reduction in office systolic (from 126 ± 5 to 121 ± 7 mm Hg; P=0.001) and a trend for diastolic blood pressure (from 75 ±7 to 73 ± 8 mm Hg; P=0.08) as well as a significant decrease in daytime and nighttime systolic and diastolic blood pressure (P<0.05 for each comparison). There was a significant reduction in the frequency of prehypertension (from 94% to 55%; P=0.02) and masked hypertension (from 39% to 5%; P=0.04) only in the CPAP group. In conclusion, effective CPAP therapy promotes significant reduction in the frequency of prehypertension and masked hypertension by promoting significant blood pressure reductions in patients with severe obstructive sleep apnea.     

持续气道正压通气对老年阻塞性睡眠呼吸暂停患者心脑血管事件的影响

目的 探讨持续气道正压通气(CPAP)治疗对老年阻塞性睡眠呼吸暂停综合征(OSAS)患者心脑血管事件的远期作用.方法 采用前瞻性队列研究对2000至2006年间诊断为中重度OSAS的老年患者进行随访,共纳入106例患者,其中男91例(85.8%),女 15 例(14.2%),年龄60～86岁,平均(73±6)岁,其中坚持进行CPAP治疗者34例,对照组72例,比较CPAP治疗与未治疗2组的心脑血管事件发生率.结果 全部受访的老年中重度OSAS患者接受随访平均观察时间3.5年,到随访结束,CPAP治疗组心脑血管事件的发生率为12%(4/34),对照组为47%(34/72),差别有统计学意义(P<0.001).经Kaplan-Meier生存分析结果显示,随访时间越长,对照组发生心脑血管事件的风险明显高于治疗组(χ2=17.0,P<0.01),是否接受CPAP治疗与心脑血管事件发生呈正相关.结论 合并中重度OSAS的老年心血管疾病患者在接受基础疾病治疗的同时,采用CPAP治疗睡眠呼吸暂停,可以减少心脑血管事件发生的风险,从而利于改善预后.     

Family aggregation of upper airway soft tissue structures in normal subjects and patients with sleep apnea

RATIONALE: Sleep apnea is believed to be a genetic disorder. Thus, we hypothesized that anatomic risk factors for sleep apnea would demonstrate family aggregation. OBJECTIVES: We used volumetric magnetic resonance imaging in a sib pair "quad" design to study the family aggregation of the size of upper airway soft tissue structures that are associated with increased risk for obstructive sleep apnea. METHODS: We examined 55 sleep apnea probands (apnea-hypopnea index [AHI]: 43.2 +/- 26.3 events/h), 55 proband siblings (AHI: 11.8 +/- 16.6 events/h), 55 control subjects (AHI: 2.1 +/- 1.7 events/h), and 55 control siblings (AHI: 4.2 +/- 4.0 events/h). The study design used exact matching on ethnicity and sex, frequency matching on age, and statistical control for visceral neck fat and craniofacial dimensions. MEASUREMENTS AND MAIN RESULTS: The data support our a priori hypothesis that the volume of the important upper airway soft tissue structures is heritable. The volume of the lateral pharyngeal walls (h(2) = 36.8%; p = 0.001), tongue (h(2) = 36.5%; p = 0.0001), and total soft tissue (h(2) = 37.5%; p = 0.0001) demonstrated significant levels of heritability after adjusting for sex, ethnicity, age, visceral neck fat, and craniofacial dimensions. In addition, our data indicate that heritability of the upper airway soft tissue structures is found in normal subjects and patients with apnea. Thus, it is not simply a consequence of the prevalence of apnea. CONCLUSIONS: This is the first time family aggregation of size of the upper airway soft tissue structures has been demonstrated.     

Influence of obstructive sleep apnea on mortality in patients with heart failure.

OBJECTIVES: This study sought to determine, in patients with heart failure (HF), whether untreated moderate to severe obstructive sleep apnea (OSA) is associated with a higher mortality rate than in patients with mild to no sleep apnea (M-NSA). BACKGROUND: Obstructive sleep apnea is common in patients with HF and exposes the heart and circulation to adverse mechanical and autonomic effects. However, its effect on mortality rates of patients with HF has not been reported. METHODS: In a prospective study involving 164 HF patients with left ventricular ejection fractions (LVEFs) < or =45%, we performed polysomnography and compared death rates between those with M-NSA (apnea-hypopnea index [AHI] <15/h of sleep) and those with untreated OSA (AHI > or =15/h of sleep). RESULTS: During a mean (+/- SD) of 2.9 +/- 2.2 and a maximum of 7.3 years of follow-up, the death rate was significantly greater in the 37 untreated OSA patients than in the 113 M-NSA patients after controlling for confounding factors (8.7 vs. 4.2 deaths per 100 patient-years, p = 0.029). Although there were no deaths among the 14 patients whose OSA was treated by continuous positive airway pressure (CPAP), the mortality rate was not significantly different from the untreated OSA patients (p = 0.070). CONCLUSIONS: In patients with HF, untreated OSA is associated with an increased risk of death independently of confounding factors.     

Effects of Surgical Weight Loss on Measures of Obstructive Sleep Apnea: A Meta-Analysis

Objective

Limited evidence suggests bariatric surgery can result in high cure rates for obstructive sleep apnea (OSA) in the morbidly obese. We performed a systematic review and meta-analysis to identify the effects of surgical weight loss on the apnea-hypopnea index.

Methods

Relevant studies were identified by computerized searches of MEDLINE and EMBASE (from inception to March 17, 2008), and review of bibliographies of selected articles. Included studies reported results of polysomnographies performed before and at least 3 months after bariatric surgery. Data abstracted from each article included patient characteristics, sample size who underwent both preoperative and postoperative polysomnograms, types of bariatric surgery performed, results of preoperative and postoperative measures of OSA and body mass index, publication year, country of origin, trial perspective (prospective vs retrospective), and study quality.

Results

Twelve studies representing 342 patients were identified. The pooled mean body mass index was reduced by 17.9 kg/m² (95% confidence interval [CI], 16.5-19.3) from 55.3 kg/m² (95% CI, 53.5-57.1) to 37.7 kg/m² (95% CI, 36.6-38.9). The random-effects pooled baseline apnea hypopnea index of 54.7 events/hour (95% CI, 49.0-60.3) was reduced by 38.2 events/hour (95% CI, 31.9-44.4) to a final value of 15.8 events/hour (95% CI, 12.6-19.0).

Conclusion

Bariatric surgery significantly reduces the apnea hypopnea index. However, the mean apnea hypopnea index after surgical weight loss was consistent with moderately severe OSA. Our data suggest that patients undergoing bariatric surgery should not expect a cure of OSA after surgical weight loss. These patients will likely need continued treatment for OSA to minimize its complications.     

Continuous positive airway pressure treatment rapidly improves insulin sensitivity in patients with obstructive sleep apnea syndrome

The obstructive sleep apnea syndrome is typically associated with conditions known to increase insulin resistance as hypertension, obesity, and diabetes. We investigated whether obstructive sleep apnea itself is an independent risk factor for increased insulin resistance and whether continuous positive airway pressure (CPAP) treatment improves insulin sensitivity. Forty patients (apnea-hypopnea index > 20) were treated with CPAP. Before, 2 days after, and after 3 months of effective CPAP treatment, hyperinsulinemic euglycemic clamp studies were performed. Insulin sensitivity significantly increased after 2 days (5.75 +/- 4.20 baseline versus 6.79 +/- 4.91 micromol/kg.min; p = 0.003) and remained stable after 3 months of treatment. The improvement in insulin sensitivity after 2 days was much greater in patients with a body mass index less than 30 kg/m2 than in more obese patients. The improved insulin sensitivity after 2 nights of treatment may reflect a decreasing sympathetic activity, indicating that sleep apnea is an independent risk factor for increased insulin resistance. The effect of CPAP on insulin sensitivity is smaller in obese patients than in nonobese patients, suggesting that in obese individuals insulin sensitivity is mainly determined by obesity and, to a smaller extent, by sleep apnea.     

Body mass index and the risk of mortality in type II diabetic patients from Verona

OBJECTIVE: The relation between body weight and mortality in type II diabetic patients has not been fully elucidated. The aim of the present study was to evaluate the impact of body weight on mortality in a well-characterized type II diabetic cohort. RESEARCH DESIGN AND METHODS: We examined a cohort of 3398 type II diabetic patients, alive on December 1986 and followed up for 10 years, to assess mortality and its causes and to investigate the relationship between body mass index (BMI) and mortality from all and specific causes. For this purpose, survival in the different quartiles of BMI was evaluated by a Cox model, controlling for sex, age, treatment, smoking, duration of diabetes, hypertension, and fasting plasma glucose. The Cox model was applied either excluding (model 1) or including (model 2) the last three variables. RESULTS: During the 10 ys of follow-up, 1212 deaths (639 women, 573 men) occurred in the cohort under study. Since the interaction between BMI and age was statistically significant (P = 0.002), survival was studied separately in people aged <65 and > or =65 y (median age of the cohort = 65.9 y). Under 65 y, a significantly higher all-cause mortality was observed in obese patients, that is, in the IV quartile (BMI> or =30.9 kg/m(2); RR = 1.74; CI 95% = 1.26-2.40), in model 1. The inclusion of hypertension, duration of diabetes, and fasting plasma glucose in the model (model 2) slightly decreased the relative risk (RR = 1.52; CI 95% = 1.10-2.11). After 65 y, higher body weight was associated with a better outcome, especially in patients belonging to the IV quartile of BMI (RR = 0.74; CI 95% = 0.62-0.90). CONCLUSIONS: In older type II diabetic patients, a moderate excess weight predicts a better survival, while obesity is a negative prognostic factor in patients younger than 65 y. In the latter patients, the effect of obesity on mortality seems to be partly mediated by hypertension, duration of diabetes, and fasting plasma glucose.     

Metabolic syndrome in Japanese patients with obstructive sleep apnea syndrome.

We investigated the prevalence of metabolic syndrome in patients with obstructive sleep apnea syndrome (OSAS) referred to a tertiary university-based medical center. A cross-sectional study of patients with a definite diagnosis of OSAS was performed using new diagnostic criteria for metabolic syndrome that were designed for the Japanese population. Clinical features and comorbidities related to metabolic syndrome were compared between 819 patients with OSAS (719 men and 100 women) and 89 control subjects without OSAS. Metabolic syndrome was significantly more common in the patients with OSAS than in the controls (49.5% vs. 22.0% for men, p < 0.01; 32.0% vs. 6.7% for women, p < 0.01). Men with OSAS (apnea-hypopnea index [AHI] > or =5/h) had a higher risk of metabolic syndrome compared with controls (odds ratio [OR]: 3.47; 95% confidence interval [CI]: 1.84-6.53). There was a significantly increased risk of metabolic syndrome in men with moderate OSAS (AHI: 15-29.9/h) (OR: 2.83; 95% CI: 1.42-5.66) and men with severe OSAS (AHI > or =30/h) (OR: 5.09; 95% CI: 2.67-9.71). Women with OSAS (AHI> or =5/h) also had an increased risk of metabolic syndrome (OR: 6.59; 95% CI: 1.47-29.38), and the risk was significantly higher in women with severe OSAS (AHI > or =30/h) (OR 14.00; 95% CI: 2.93-66.82). Risk factors for metabolic syndrome differed by gender: in men, age, body mass index (BMI), and OSAS (AHI > or =15/h) were significantly associated with metabolic syndrome, whereas, in women, BMI was the only risk factor for metabolic syndrome. The increase of metabolic syndrome in Japanese OSAS patients suggests that this patient population is burdened with multiple risk factors for cardiovascular disease.