Obstructive sleep apnea syndrome and cardiovascular disease: The influence of C-reactive protein

Table 1 Previous studies on the relationship between obstructive sleep apnea syndrome, C-reactive protein and other inflammatory markers

Ref.	Study population	Inflammatory markers	Findings
Chami et al[78]	355 OSAS patients 545 controls	CRP, fibrinogen, IL-6, TNF-α, TNF-R2, CD40-ligand, P-selectin, ICAM1 MCP-1 after PSG	AHI was associated with CRP, IL-6, fibrinogen, ICAM, and P-selectin but not with TNF-α, TNF-R2, CD40-ligand, or MCP-1 levels The associations were substantially attenuated, and remained statistically significant only for IL-6, after adjustment for BMI
Kurt et al[79]	78 OSAS patients 20 controls	CRP, hemoglobin, RDW, MPV, PDW, and white blood cell	The severity of OSAS was not correlated with CRP, MPV, and RDW
Svensson et al[80]	136 OSAS patients 262 controls	CRP, TNF-α, IL-6, myeloperoxidase and lysozyme	The levels of CRP, IL-6 and lysozyme were significantly higher in subjects with AHI > 15 compared with subjects with lower AHI In multiple linear regressions adjusting for age, waist circumference and smoking, independent correlations between ODI and inflammation were found for IL-6 and TNF-α
Lin et al[38]	109 OSAS patients 35 Controls	Serum glucose, and lipid profile comprising total cholesterol, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol and triglycerides hs-CRP	CRP and metabolic score significantly increased with the aggravation of OSA severity OSA was independently associated with sum of metabolic components and CRP
Guven et al[48]	47 OSAS patients 29 controls	CRP	The serum CRP levels were significantly higher in the OSA group than in the control group In multiple regression analysis, elevated hs-CRP levels were associated with AHI which was independent of obesity
Kokturk et al[20]	94 OSAS patients 57 controls	CRP and conventional cardiovascular risk factors such as total cholesterol, low-density lipoprotein, high-density lipoprotein, very low density lipoprotein, and triglycerides	CRP levels were significantly elevated in the OSAS group compared to the non-OSAS group CRP levels were independently associated with AHI
Shamsuzzaman et al[19]	22 OSAS patients 20 controls	CRP	CRP levels were independently associated with OSA severity
Punjabi et al[21]	69 OSAS patients	CRP	A strong association was found between degree of SDB and serum levels of CRP, with or without adjustment for age and several measures of adiposity. Moreover, an independent association between serum CRP levels and nocturnal hypoxia was also observed, whereas no association was noted with parameters of sleep architecture
Yokoe et al[22]	30 OSAS patients 14 controls	CRP and IL-6	CRP and IL-6 and production of IL-6 were significantly higher in patients with OSAS than in obese control subjects. The severity of OSAS and BMI were independently related to levels of CRP, whereas BMI and apnea-related nocturnal hypoxia were independently related to levels of IL-6 in patients with OSAS
Hayashi et al[23]	60 OSAS patients 30 controls	Hsp-70, TF, MCP-1, hs-CRP, hepatocyte growth factor and plasma vascular endothelial growth factor	Serum CRP, TF, MCP-1 and Hsp-70 levels were significantly higher in OSAS compared with control subjects However, the best correlation with serum CRP levels was BMI and it was the most significant determinant for CRP
Schiza et al[65]	528 OSAS patients	CRP	CRP levels were independently associated with OSAS severity

AHI: Apnea hypopnea index; BMI: Body mass index; ODI: Oxygen desaturation index; OSAS: Obstructive sleep apnea syndrome; CRP: C-reactive protein; hs-CRP: Highly sensitive C-reactive protein; IL-6: Interleukin-6; Hsp-70: Heat shock protein-70; TF: Tissue factor; MCP-1: Monocyte chemotactic protein-1.