Effect of continuous positive airway pressure on C-reactive protein levels in sleep apnea: a meta-analysis

Evaluate the effects of continuous positive airway pressure (CPAP) on C-reactive protein (CRP) levels, reported either as a primary or secondary end point among patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) based on a meta-analysis of published studies.English-language searches of PubMed, Ovid, and the Cochrane databases were completed. Reference sections of identified studies were also examined for additional relevant articles to review.Studies of adult patients with OSAHS who reported pre- and post-CPAP treatment CRP were reviewed and analyzed. Two independent reviewers extracted data from 10 peer-reviewed studies, which were combined using a random effects meta-analysis model.The CPAP treatment was found to lead to a significant reduction in CRP levels (17.8%, P = .002). This corresponds to an effect size of -0.485 (-0.731, -0.240). Sensitivity analysis was done to determine the impact of study design. Both case-control studies and case-series studies yielded a significant effect. Sensitivity analysis also yielded a significant effect for studies with average body mass index30, studies where CPAP was employed over automatic positive airway pressure, and studies treating patients ≤ 3 months. Analysis of publication bias, however, revealed a likelihood of "missing" studies.Although there is a significant lack of high-quality studies addressing this question, this analysis suggests that treatment with CPAP leads to a statistically significant reduction in CRP levels. However, the mean pre- and posttreatment CRP levels observed are considered "high risk" for cardiovascular morbidity. The clinical significance of this finding as it relates to cardiovascular risk reduction and the relationship between CRP and OSAHS requires further study.