The relationship between obstructive sleep apnea hypopnea syndrome (OSAHS) and a variety of disease from obesity, type 2 diabetes mellitus and cardiovascular disease has been investigated previously. Reduced adiponectin levels are also associated with increased risk of these disease. However, whether serum/plasma adiponectin levels in OSAHS patients are lower than their counterparts remain controversial. Therefore, this study evaluated the association between serum/plasma adiponectin levels and OSAHS. We performed a comprehensive literature search to locate eligible articles published on electronic databases including PubMed, EMBASE, Cochrane Library, WANFANG (Chinese database), VIP (Chinese Database) and Chinese National Knowledge Infrastructure (CNKI). The methodological quality of included studies was evaluated using the Newcastle-Ottawa scale (NOS). Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated as effect size. Heterogeneity test was performed by Cochrane Q test and I2 test. Subgroup analysis and meta-regression analysis were employed to detect the sources of the heterogeneity. RevMan 5.3 and Stata 12.0 software were used in this meta-analysis for data synthesis. A total of 20 eligible studies with 28 databases involving 1356 participants were included in this meta-analysis. Results revealed that serum/plasma adiponectin levels in OSAHS patients were significantly lower than that in controls [SMD = − 0.71, 95% CI = − 0.92 to − 0.49, p < 0.001]. Subgroup analysis indicated that the heterogeneity would decreased when subgroup analysis was stratified by race. In addition, meta-regression analysis also suggested that the adiponectin levels were only significantly correlated with race. The removal of any independent study did not affect the pooled SMD in the sensitivity analysis. The serum/plasma adiponectin levels were significantly lower in OSAHS patients than that in control subjects, suggesting a possible role of adiponectin in OSAHS pathogenesis, deserves further studies as a potential marker of OSAHS.

(1) Aim: We aim to evaluate the association between arousals during sleep and subclinical coronary atherosclerosis detected by coronary computed tomography angiography (CTA) in patients with obstructive sleep apnea (OSA). (2) Methods: This was a cross-sectional study. Consecutive newly diagnosed OSA patients, who underwent coronary CTA examinations within 3 months of the sleep study, were eligible. We used the arousal index (ArI) derived from polysomnography to assess arousals during sleep and a semi-automated plaque quantification software to characterize and quantify the subclinical coronary atherosclerosis. Multiple regression models were used to evaluate the associations of the ArI with the coronary atherosclerotic plaque presence, volume, and composition. (3) Results: A total of 99 patients with OSA were included in the study. In the multivariable models, patients with a high ArI (ArI > 32.2 events/h) were more likely to have coronary plaques compared to those with a low ArI (ArI ≤ 32.2 events/h) (OR: 3.29 [95% CI: 1.284 to 8.427], p = 0.013). Furthermore, the ArI exhibited significant associations with total (β = 0.015), noncalcified (β = 0.015), and low-attenuation (β = 0.012) coronary plaque volume after accounting for established risk factors (p = 0.008, 0.004, and 0.002, respectively). However, no association between the ArI and calcified plaque volume was found. (4) Conclusion: Repetitive arousals during sleep are associated with an increased coronary plaque burden in patients with OSA, which remained robust after adjusting for multiple established cardiovascular risk factors.