Elsevier

Atherosclerosis

Volume 229, Issue 2, August 2013, Pages 489-495
Atherosclerosis

Obstructive sleep apnea and cardiovascular risk: Meta-analysis of prospective cohort studies

https://doi.org/10.1016/j.atherosclerosis.2013.04.026Get rights and content

Abstract

Background

Previous studies suggest obstructive sleep apnea (OSA) may increase cardiovascular risk, but the results are inconclusive due to various limitations. We aimed to systematically evaluate the effect of OSA on the incidence of cardiovascular events by a meta-analysis of prospective cohort studies.

Methods

We searched multiple electronic databases for studies that examined the prospective relationship between OSA and incidence of coronary heart disease (CHD), stroke, or total cardiovascular diseases (CVD) among adults. Either fixed- or random-effects models were used to calculate the pooled risk estimates. Sensitivity analysis was conducted to examine the robustness of pooled outcomes.

Results

Of 17 studies included, 9 reported results on total CVD, 7 reported on fatal or non-fatal CHD, and 10 reported on fatal or non-fatal stroke. The pooled relative risks (95% confidence interval) for individuals with moderate-severe OSA compared with the reference group were 2.48 (1.98–3.10) for total CVD, 1.37 (0.95–1.98) for CHD, and 2.02 (1.40–2.90) for stroke. These results did not materially change in the sensitivity analyses according to various inclusion criteria.

Conclusions

In conclusion, findings from this meta-analysis supported that moderate-severe OSA significantly increased cardiovascular risk, in particular stroke risk.

Introduction

Obstructive sleep apnea (OSA) is the most common form of sleep disordered breathing that repeatedly narrows the throat during sleep and either partially or completely blocks the airways. OSA is common and affects 3%–7% of the general population [1], [2]. The prevalence is undoubtedly rising given the epidemic of obesity, which is the most important risk factor for the disease [3]. OSA has become an important public health problem as it is associated with a wide range of health-related outcomes, including hypertension [4], [5], type 2 diabetes [6], and cardiovascular events [7].

In particular, the effects of OSA on cardiovascular health continue to receive widespread attention. A number of prospective cohort studies aiming to determine whether OSA is causally associated with cardiovascular risk have been published [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. However, prior studies have important limitations, including small sample size, clinic-based design, enrolling patients with history of cardiovascular diseases (CVD) at baseline, and insufficient control for potential confounding factors. A previous meta-analysis [7] reported a significant positive association between OSA and stroke (pooled odds ratio = 2.24, 95% confidence interval [CI]: 1.57–3.19) but found insufficient evidence for coronary heart disease (CHD) (pooled odds ratio = 1.56, 95% CI: 0.83–2.91). However, that meta-analysis only included studies published before 2011 and had limited number of studies for analysis (5 for stroke and 4 for CHD); also, the relationship of OSA with total CVD was not assessed. Since then, several large cohort studies [22], [23], [24] were published and could add more evidence to the OSA-CVD link.

Therefore, the purpose of this study was to systematically evaluate the effect of OSA on the incidence of cardiovascular events by a meta-analysis of prospective cohort studies.

Section snippets

Data sources

The present meta-analysis was planned, conducted and reported according to the checklist of Meta-analysis of Observational Studies in Epidemiology [25]. We searched for prospective cohort studies examining the association between OSA and cardiovascular events, using PubMed, Web of Science, and Cochrane Library databases. The first search was carried out in May 2012, and an updated one was performed in October 2012. The search terms included sleep disordered breathing, obstructive sleep apnea,

Literature search

Overall, we retrieved 2009 citations from electronic databases. After the initial screening of title and abstract, the majority of the citations were excluded, mainly because they were reviews, cross-sectional studies, retrospective studies, conducted among children, or did not examine relevant exposure or outcomes. Among the 31 articles for full-text review, 14 were further excluded, leaving 17 articles [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23]

Discussion

Data from the present meta-analysis support the notion that OSA is an important, emerging risk factor of CVD. Individuals with moderate-severe OSA had an almost 2.5-fold risk of developing cardiovascular events and had a 2.0-fold risk of developing stroke, though the association between OSA and CHD was borderline significant and somewhat weaker.

The complex mechanisms underlying the increase of consequent cardiovascular events in OSA patients are not well understood. As reviewed by Kohler and

Acknowledgements

This work is supported in part by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the National Natural Science Foundation of China [No. 81273067]. The authors have no conflicts of interest to report.

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