The effect of continuous positive airway pressure on circulating malondialdehyde among obstructive sleep apnea patients: a meta-analysis

Background Obstructive sleep apnea (OSA) has been demonstrated to be associated with an increase of oxidative stress. However, whether circulating malondialdehyde (MDA), a widely used biomarker of oxidative stress, could be reduced by the treatment of OSA by continuous positive airway pressure (CPAP) is debated. The present meta-analysis was performed to determine the effect of CPAP treatment on circulating MDA among patients with OSA. Methods A systematic search of PubMed, Embase, and Web of Science was performed for literature covering the period between 1967 and August 2019. Standardized mean difference (SMD) was calculated to estimate the treatment effects of pre- and post-CPAP therapy. Results A total of 10 studies with 220 patients were included in this meta-analysis. A significant decrease in circulating MDA was observed after CPAP treatment (SMD = 1.164, 95% CI = 0.443 to 1.885, z = 3.16, p = 0.002) in OSA patients. Subgroup analyses revealed that CPAP therapy was associated with a significant decrease of circulating MDA in elder (SMD = 1.629, 95% CI = 0.265 to 2.994, z = 2.34, p = 0.019), more obese patients (SMD = 0.954, 95% CI = 0.435 to 1.473, z = 3.61, p = 0.000), more severe OSA patients (SMD = 0.879, 95% CI = 0.421 to 1.336, z = 3.76, p = 0.000), patients with therapeutic duration ≥ 3 months (SMD = 1.867, 95% CI = 0.563 to 3.172, z = 2.80, p = 0.005), and patients with good compliance (SMD = 1.004, 95% CI = 0.703 to 1.305, z = 6.54, p = 0.000). Conclusions This meta-analysis suggested that CPAP therapy exerted significant lowering effects on circulating MDA, especially in elder, more obese, and more severe OSA patients and patients with good compliance as well as longer duration of CPAP application.