Circulating fibrinogen levels are elevated in patients with obstructive sleep apnea: a systemic review and meta-analysis

Objective: Fibrinogen is believed to play a role in the pathophysiology of obstructive sleep apnea (OSA) and many studies have assessed circulating fibrinogen concentrations in OSA patients. However, the results from these studies were not consistent. To assess the association of circulating fibrinogen levels and OSA, a meta-analysis was performed. Methods: PubMed, Embase and Web of Science databases were searched for eligible studies. Data were extracted, and then weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated. Results: A total of 25 studies involving 1480 cases and 2312 controls were included in this meta-analysis. Combined data indicated that the circulating fibrinogen levels were higher in OSA patients than in controls (WMD: 0.38 g/L, 95% CI [0.29-0.47 g/L], p < 0.001; I-2 = 80.3%, p < 0.001). In the subgroup analyses by disease severity, there were similar results in mild-moderate OSA patients (WMD: 0.27 g/L, 95% CI [0.14-0.41 g/L], p < 0.001; I-2 = 29.3%, p = 0.185) and severe OSA patients (WMD: 0.54 g/L, 95% CI [0.28-0.79 g/L], p < 0.001; I-2 = 65.9%, p = 0.012). Furthermore, in another subgroup analysis, the circulating fibrinogen levels were higher in OSA patients than those in controls who were matched for important potential confounders (WMD: 0.41 g/L, 95% CI [0.21-0.60 g/L], p < 0.001; I-2 = 62.0%, p = 0.003). Conclusions: This systematic review and meta-analysis reveals that circulating fibrinogen levels are elevated in patients with OSA. (C) 2019 Elsevier B.V. All rights reserved.