Associations between cardiometabolic phenotypes and levels of TNF-α, CRP, and interleukins in obstructive sleep apnea

Obstructive sleep apnea (OSA) shows a chronic inflammatory state which is often accompanied by cardiometabolic phenotypes. The aim of this study was to investigate whether or not there were differences of inflammatory proteins levels in patients with OSA with and without a certain phenotype so as to explore the associations between inflammation and additional OSA phenotypes.

The literature was systematically screened and available data were collected on levels of tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), and several interleukins (ILs) in patients with OSA with and without a certain phenotype. Overall effect size of standard mean difference (SMD) was used to compare the expression of differences between the two groups. Data analysis was conducted by Review Manager 5.3, and the threshold of p value was set as < 0.05.

A total of 31 articles were included, covering five traits of obesity, hypertension (HBP), metabolic syndrome (MS), heart disease, and sex. There were elevated levels of TNF-α (SMD = 0.63, p = 0.03), CRP (SMD = 0.64, p = 0.0001), and IL-6 (SMD = 0.83, p = 0.008) levels in OSA with obesity. Also, OSA with HBP showed significant increases of TNF-α (SMD = 0.36, p = 0.02), CRP (SMD = 0.98, p = 0.01), and IL-6 (SMD = 0.76, p < 0.0001) levels. A higher CRP level was also observed in OSA with MS (SMD = 0.31, p = 0.004) and female sex (SMD = 0.21, p = 0.002). There were no statistical differences for IL-1β (p = 0.22) and CRP (p = 0.14) levels of OSA with obesity and heart disease respectively compared with OSA without corresponding phenotype. TNF-α (p = 0.66) and IL-6 (p = 0.49) levels also lacked statistically significant differences between female and male patients with OSA.

Our results revealed that inflammatory proteins TNF-α, CRP, and IL-6 levels were higher in obese and hypertensive patients with OSA and CRP levels were higher in OSA with metabolic syndrome, highlighting a link between inflammation and cardiometabolic complications in patients with OSA.