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14-06-2012 | Psychology | Article

CPAP therapy reduces inflammation in OSA patients


Free abstract

MedWire News: Individuals with obstructive sleep apnea (OSA) successfully treated with continuous positive airway pressure (CPAP) have significant reductions in systemic inflammation, research shows.

In a meta-analysis, researchers report that CPAP was associated with a significant reduction in C-reactive protein (CRP) levels.

"Based on our results, the change in CRP levels should be considered as a potential predictor for CPAP therapy among OSA patients," suggest Yongzhong Guo (Guangzhou Medical College, China) and colleagues.

Reporting their findings in Sleep and Breathing, the researchers note that OSA is a recognized risk factor for cardiovascular diseases and death from any cause.

Despite the association with cardiovascular disease, the underlying mechanisms supporting the link with OSA are not fully known. It has been suggested that the various inflammatory processes, which are activated by the intermittent hypoxia, might contribute to endothelial dysfunction and lead to cardiovascular events.

In the present study, Guo and colleagues performed a meta-analysis of studies that examined the effect of CPAP on CRP levels in OSA patients. In all the studies, patients were treated with CPAP for a minimum of 4 weeks and used the device for more than 4 hours per night.

In total, 14 studies with 1199 OSA patients were identified. The average patient age was 51 years and the mean body mass index (BMI) was 34.7 kg/m2.

Overall, eight studies showed a significant reduction in CRP levels after CPAP therapy and six studies failed to show a benefit.

In a random-effects model that accounted for heterogeneity across the trials, treatment with CPAP therapy significantly reduced CRP when measured as the change in the standardized mean difference (SMD), at a score of 0.64.

SMD was used for analyzing the summary estimates instead of the absolute levels of CRP because CRP was measured and reported differently in various laboratories, explain the researchers. They add that an SMD score of 0.64 suggests a moderate effect of treatment.

To date, just one randomized, controlled clinical trial has been performed testing the effect of CPAP therapy in CRP, and this study failed to show a significant reduction.

Given the findings of the meta-analysis, Guo and colleagues state that further prospective multicenter studies are "needed to explore the precise impact of CPAP therapy in systemic inflammation."

By MedWire Reporters

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