Diagnostic Role of Circulating Endocan Levels in Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis.

Endocan, as an endothelial cell damage marker, plays role in several cardiovascular and non-cardiovascular diseases. This systematic review and meta-analysis evaluates the role of endocan as a potential diagnostic or prognostic biomarker for obstructive sleep apnea (OSA). International databases including PubMed, Embase, Web of Science, and Scopus were searched for relevant studies assessing endocan levels in OSA patients compared with healthy controls or within different severities or comorbidities of OSA. Random-effect meta-analysis was performed in order to calculate the standardized mean difference (SMD) and 95% confidence interval (CI) of serum/plasma endocan in all comparisons. A total of 10 studies were included in our systematic review, among which seven were used in meta-analysis. Meta-analysis showed that endocan levels were significantly higher in patients with OSA compared with healthy controls (SMD 1.29, 95% CI 0.64-1.93, P < .001) and this was not different between serum and plasma subgroups. However, there was no statistical difference between severe and non-severe OSA patients (SMD .64, 95% CI -.22 to 1.50, P = .147). Considerably, higher endocan levels in patients with OSA in comparison with non-OSA individuals might have clinical implications. This association warrants further research due to its potential use as a diagnostic and prognostic biomarker.