Obstructive sleep apnea and biomarkers of inflammation in ischemic stroke

Despite a confirmed association between obstructive sleep apnea (OSA) and stroke, the pathogenesis of OSA in stroke has not been hitherto clarified. The aim of this study was to evaluate the relationship between respiratory abnormalities and atherogenic pro-inflammatory markers, interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in acute ischemic stroke patients.

Nocturnal polygraphy was performed in 50 consecutive patients with acute ischemic stroke in the first week after the event. Levels of inflammatory markers (IL-6, IL-1β and TNF-α) were determined from morning blood samples and comparatively analyzed between cases with and without severe OSA and with age-matched controls.

All patients with acute ischemic stroke, 31 men, mean age (64.3 ± 7.7 years), had apnea-hypopnea index (AHI) > 5 and 35 (70%) had severe OSA (AHI ≥ 30). Hypertension was more frequent in patients with severe OSA (85.7%) when compared to controls (40.0%) (P = 0.002). Stroke outcome, assessed by the Barthel index, tended to be more severe (P = 0.06) in cases with severe OSA. Patients with mild/moderate OSA and with severe OSA showed higher levels of IL-6 when compared to controls (P = 0.01 and P = 0.000, respectively). Among cases with acute stroke and severe OSA, IL-6 levels were correlated with lower oxyhemoglobin desaturation (r=-0.30; P = 0.001) and with the desaturation index (r = 0.15; P = 0.02).

IL-6, an atherogenic marker, shows a commensurate increase in stroke patients with OSA. It is correlated with oxyhemoglobin desaturation and with desaturation index and may be a surrogate measure to evaluate continuous positive airway pressure therapy.