title: Hypoxia and inflammation indicate significant differences in the severity of obstructive sleep apnea within similar apnea-hypopnea index groups.
abstract: OBJECTIVE
  We determined whether hypoxia parameters are associated with C-reactive protein (CRP), mean platelet volume (MPV), white matter hyperintensity (WMH), and the severity of obstructive sleep apnea (OSA), and also evaluated whether hypoxia parameters, CRP, MPV, and WMH differ in patients with similar apnea-hypopnea index (AHI) scores.
  
  
  METHODS
  A total of 297 patients, who were evaluated using polysomnography, were assessed retrospectively. The measured hypoxia parameters included total sleep time with oxygen saturation <90% (ST90), percentage of cumulative time with oxygen saturation <90% (CT90), and lowest oxygen saturation (min SaO2). The patients were divided into subgroups according to their CT90values, and patients with different AHI severities were divided into subgroups according to their ST90and min SaO2levels.
  
  
  RESULTS
  Hypoxia parameters are associated with CRP, MPV, WMH, and the severity of OSA (P < 0.05). The hypoxia parameters differed in all subgroup analyses of similar AHI groups (P < 0.001), and CRP differed only in severe OSA (P < 0.008, P < 0.001). In subgroup analyses of similar AHI groups, MPV and WMH were not significantly different (P > 0.05). Above the hypoxia threshold (CT90≥ 10%) of CRP, MPV increased significantly and the presence of WMH increased twofold.
  
  
  CONCLUSIONS
  These data suggest that increased hypoxia severity may mediate increased inflammation and activation of platelets and contribute to the pathogenesis of WMH in patients with OSA. In addition, patients with severe OSA may show significant variability in inflammation and vascular risk. Further prospective data are needed.
authors.affiliation: Department of Neurology, Baskent University, Ankara, Turkey. aynuryilmazavci@gmail.com.
authors.forename: Aynur
authors.initials: A
authors.lastname: Yilmaz Avci
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, Baskent University, Ankara, Turkey.
authors.forename: Suat
authors.initials: S
authors.lastname: Avci
authors.affiliation: Department of Chest Disease, Baskent University, Ankara, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Lakadamyali
authors.affiliation: Department of Neurology, Baskent University, Ankara, Turkey.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Can
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000378:metabolism* / Q000503:physiopathology*; D013997:Time Factors
keywords: C-reactive protein; Hypoxia; Inflammation; Platelets; Sleep disordered breathing; White matter hyperintensity