Background The relationship between obstructive sleep apnoea (OSA) and stroke remains unclear. We conducted a systematic review to determine the incident risk of stroke among patients with OSA.

Methods and Results We searched MEDLINE and EMBASE for prospective studies that followed up patients with OSA (and controls) for over 12 months for incident stroke. Outcomes data were pooled using random effects meta–analysis and heterogeneity assessed with the I2 statistic. Regression analysis was performed to quantify the effects of OSA severity (using the apnoea–hypopnea index). For meta–analysis we identified 5 relevant studies from 1731 citations;^{1–5 4} were adjusted for other stroke risk factors.^1–4. OSA was associated with incident stroke (8435 participants), odds ratio (OR) 2.24; 95% confidence interval (CI), 1.57–3.19; I2=7%. A significant association was seen in studies predominantly on men (OR, 2.87; 95% CI, 1.91–4.31), whereas data on women were sparse. The relationship retained significance when studies with unadjusted data,⁵ elderly populations³ or outcomes including transient ischaemic attack^{2 5} were excluded. Regression analysis showed greater likelihood of stroke with increasing apnoea–hypopnea index values. A robust molecular literature is illuminating the pathogenesis of OSA–related cardiovascular events.

Conclusion As OSA appears to be independently associated with stroke (and continuous positive airway pressure (CPAP) reduces such cardiovascular outcomes in OSA6), clinicians should look out for the symptoms in stroke patients so appropriate risk mitigation strategies may be implemented. Equally, patients with OSA but no history of stroke should receive appropriate management to lower their cardiovascular risk, be it through treatment of OSA with CPAP or modification of traditional risk factors such as obesity and hypertension.