Obstructive sleep apnoea and risks of all-cause mortality: preliminary evidence from prospective cohort studies

Purpose A meta-analysis of prospective cohort studies was conducted to clarify the association between obstructive sleep apnoea (OSA) and future risk of all-cause mortality. Methods Eligible studies were identified by searching the PubMed and EMBASE databases up to July 2015. Pooled hazard ratios (HRs) and their corresponding 95 % confidence intervals (CIs) were calculated to estimate the association between OSA and risk of all-cause mortality. Sources of heterogeneity were identified by subgroup and meta-regression analyses. Results Twelve prospective cohort studies involving 34,382 participants were included in this meta-analysis. The pooled HR of all-cause mortality was 1.262 (95 % CI 1.093–1.431) with significant heterogeneity. Subgroup analyses indicated that the pooled HRs of all-cause mortality in patients with mild, moderate and severe OSA were 0.945 (95 % CI 0.810–1.081), 1.178 (95 % CI 0.978–1.378) and 1.601 (95 % CI 1.298–1.902), respectively. OSA severity could be a possible sources of heterogeneity. Existing publication bias produced a minor contribution to effect size. Conclusion Severe, but not mild to moderate, OSA is significantly associated with increased risk of all-cause mortality.