Effect of continuous positive airway pressure on liver enzymes in obstructive sleep apnea: A meta‐analysis

Background Previous studies have suggested that obstructive sleep apnea (OSA) was associated with nonalcoholic fatty liver disease (NAFLD). However, the impact of OSA treatment using continuous positive airway pressure (CPAP) on liver enzymes remained controversial. This meta‐analysis was conducted to determine whether CPAP therapy could reduce liver enzyme levels. Methods Two reviewers independently searched PubMed, Cochrane library, Embase and Web of Science before December 2015. Information on characteristics of subjects, study design and pre‐ and post‐CPAP treatment of serum ALT and AST was extracted for analysis. A total of five studies with seven cohorts that included 192 patients were pooled into meta‐analysis. Results CPAP was associated with a statistically significant decrease on both ALT and AST levels in OSA patients (WMD = 8.036, 95% CI = 2.788–13.285, z = 3.00, P = .003 and WMD = 4.612, 95% CI = 0.817–8.407, z = 2.38, P = .017, respectively). Subgroup analyses indicated that CPAP therapy was more effective in OSA patients with treatment duration > 3 mo (WMD = 12.374, 95% CI = 2.727–22.020, z = 2.51, P = .012 for ALT and WMD = 7.576, 95% CI = 1.781–13.370, z =2.56, P = .010 for AST). Conclusion This meta‐analysis suggested that CPAP was associated with a statistically significant decrease on liver enzymes in OSA patients. Further large‐scale well‐designed RCTs with long‐term follow‐up are required to clarify this issue.