The differences in plasma/serum ghrelin levels between obstructive sleep apnea-hypopnea patients and controls: A protocol for systematic review and meta-analysis

BACKGROUND: The association between obstructive sleep apnea-hypopnea syndrome (OSAHS) and plasma/serum ghrelin levels remains controversial. We performed a meta-analysis to evaluate the difference in plasma/serum ghrelin levels between OSAHS patients and controls. METHODS: Database of PubMed, SCI, and Elsevier were searched entirely. Two independents identified eligible studies of ghrelin levels in OSAHS patients. ReviewManager (version 5.3) was adopted for data synthesis. RESULTS: The meta-analysis A pooled the comparison of ghrelin concentrations in OSAHS patients and controls, which included 7 studies and involving 446 participants. The result of the meta-analysis A indicated that plasma/serum ghrelin levels were no significant differences between the OSAHS group and the control group (standard mean difference (SMD) = 0.08, 95% confidence interval (CI) = −0.12 to 0.28, P = .43). As a supplementary, meta-analysis B pooled the comparison of plasma/serum ghrelin levels in OSAHS patients before and after continuous positive airway pressure (CPAP) therapy, which included 155 participants from 4 studies, it revealed that plasma/serum ghrelin levels were no significant differences between before and after CPAP therapy (SMD = 0.12, 95%CI = −0.07 to 0.31, P = .22). CONCLUSION: The meta-analysis A demonstrated that plasma/serum ghrelin levels were no significant differences between the OSAHS group and the control group. The meta-analysis B showed plasma/serum ghrelin levels have no significant changes after CPAP therapy in OSAHS patients.