Early evidence of increased risk for metabolic syndrome in young men with latent obstructive sleep apnea

The association between obstructive sleep apnea and metabolic syndrome: a systematic review and meta-analysis

Background

Obstructive sleep apnea (OSA) is characterized by repeated episodes of obstruction of the upper airway. Numerous studies have indicated a relationship between OSA and metabolic syndrome (MS), but the results remain debatable. We aimed to perform a systematic review and meta-analysis to evaluate the association between OSA and MS.

Methods

We searched electronic databases (PubMed, EMBASE, and ISO Web of Knowledge) up to September 2014 with English-language restriction. Cross-sectional, case–control, and cohort studies in which the presence of OSA was assessed by objective measurements, the exposure of interest was OSA, and the outcome of interest was the presence (or incidence) of MS were included. The adjusted odds ratios (ORs) (or relative risk) and 95 % confidence intervals (CIs) were extracted and pooled. Sensitivity analyses were conducted, and heterogeneity and publication bias were assessed.

Results

Overall, 15 cross-sectional (2456 patients with OSA and 1705 subjects without OSA), five case–control (1156 OSA patients and 404 controls), and no cohort studies were included. The pooled ORs of MS in individuals with OSA for cross-sectional and case–control studies were 2.87 (95 % CI: 2.41–3.42) and 2.56 (95 % CI: 1.98–3.31), respectively. There was clinically unimportant (I² = 20 %) and moderate (I² = 35 %) between-study heterogeneity of the analysis. The pooled crude ORs of MS in individuals with mild and moderate-to-severe OSA was 2.39 (95 % CI: 1.65–3.46) and 3.45 (95 % CI: 2.33–5.12), respectively, and there was substantial heterogeneity in the meta-analyses (I² = 53 % and I² = 63 %, respectively). However, no evidence of publication bias was detected.

Conclusions

OSA is shown to be associated with MS, although causality between these two factors has not been demonstrated yet. Future cohort and randomized controlled studies are needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0102-3) contains supplementary material, which is available to authorized users.

Effect of obstructive sleep apnea hypopnea syndrome on lipid profile: a meta-regression analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with obesity, metabolic syndrome, and dyslipidemia, which may be related to decrease androgen levels found in OSA patients. Dyslipidemia may contribute to atherosclerosis leading to increasing risk of heart disease.

METHODS

Systematic review was conducted using PubMed and Cochrane library by utilizing different combinations of key words; sleep apnea, obstructive sleep apnea, serum lipids, dyslipidemia, cholesterol, total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), and triglyceride (TG). Inclusion criteria were: English articles, and studies with adult population in 2 groups of patients (patients with OSA and without OSA). A total 96 studies were reviewed for inclusion, with 25 studies pooled for analysis.

RESULTS

Sixty-four studies were pooled for analysis; since some studies have more than one dataset, there were 107 datasets with 18,116 patients pooled for meta-analysis. All studies measured serum lipids. Total cholesterol pooled standardized difference in means was 0.267 (p = 0.001). LDL cholesterol pooled standardized difference in means was 0.296 (p = 0.001). HDL cholesterol pooled standardized difference in means was -0.433 (p = 0.001). Triglyceride pooled standardized difference in means was 0.603 (p = 0.001). Meta-regression for age, BMI, and AHI showed that age has significant effect for TC, LDL, and HDL. BMI had significant effect for LDL and HDL, while AHI had significant effect for LDL and TG.

CONCLUSION

Patients with OSA appear to have increased dyslipidemia (high total cholesterol, LDL, TG, and low HDL).

Exercise training improves sleep pattern and metabolic profile in elderly people in a time-dependent manner

Aging and physical inactivity are two factors that favors the development of cardiovascular disease, metabolic syndrome, obesity, diabetes, and sleep dysfunction. In contrast, the adoption a habitual of moderate exercise may present a non-pharmacological treatment alternative for sleep and metabolic disorders. We aimed to assess the effects of moderate exercise training on sleep quality and on the metabolic profile of elderly people with a sedentary lifestyle. Fourteen male sedentary, healthy, elderly volunteers performed moderate training for 60 minutes/day, 3 days/week for 24 wk at a work rate equivalent to the ventilatory aerobic threshold. The environment was kept at a temperature of 23 ± 2°C, with an air humidity 60 ± 5%. Blood and polysomnographs analysis were collected 3 times: at baseline (1 week before training began), 3 and 6 months (after 3 and 6 months of training). Training promoted increasing aerobic capacity (relative VO₂, time and velocity to VO_2max; p < 0.05), and reduced serum NEFA, and insulin concentrations as well as improved HOMA index (p < 0.05), and increased adiponectin levels (p < 0.05), after 3 months of training when compared with baseline data. The sleep parameters, awake time and REM sleep latency were decreased after 6 months exercise training (p < 0.05) in relation baseline values. Our results demonstrate that the moderate exercise training protocol improves the sleep profile in older people, but the metabolism adaptation does not persist. Suggesting that this population requires training strategy modifications as to ensure consistent alterations regarding metabolism.

Increased central adiposity in morbidly obese patients with obstructive sleep apnoea

BACKGROUND

With the growing epidemic of obesity, few data are available regarding adipose distribution and the severity of sleep apnoea. Our aim was to measure precisely adipose distribution with dual-energy X-ray absorptiometry (DXA) in a morbidly obese population with and without obstructive sleep apnoea (OSA).

METHODS

Morbidly obese female subjects without a history of OSA underwent overnight polysomnography and DXA analysis. Subject demographics, DXA variables, serum laboratory markers and physical exam characteristics were compared between individuals with and without OSA.

RESULTS

For the study population (n= 26), mean body mass index (BMI) was 45.9 ± 7.8 kg/m(2); mean age was 47.5 ± 10.2 years and all were female. The central adiposity ratio (CAR) was higher in individuals with OSA (apnoea-hypopnoea index > 5) than those without OSA (1.1 ± 0.05 vs 1.0 ± 0.04; P = 0.004). No difference was observed in Epworth Sleepiness Scale scores, body mass index (BMI) or neck circumference between groups.

CONCLUSIONS

OSA is associated with increased central adipose deposition in patients with a BMI of >40 kg/m(2). These data may be helpful in designing future studies regarding the pathophysiology of OSA, and potential treatment options.