title: Effects of obesity on the association between long-term sleep apnea treatment and changes in interleukin-6 levels: the Icelandic Sleep Apnea Cohort.
abstract: The aim of this study was to evaluate changes in interleukin (IL)-6 and soluble IL-6 receptor levels in obstructive sleep apnea patients and assess the role of positive airway pressure treatment and obesity on these changes. A total of 309 newly diagnosed subjects with sleep apnea from the Icelandic Sleep Apnea Cohort were referred for treatment and reassessed at a 2-year follow-up. Full treatment was defined objectively as use ≥ 4 h day(-1) and ≥ 20 days month(-1). At the 2-year follow-up, there were 177 full users, 44 partial users and 88 non-users. The mean change in biomarker levels from baseline to the 2-year follow-up was assessed in a primary model that included adjustment for baseline biomarker levels, baseline body mass index and change in body mass index, as well as after adjustment for numerous relevant covariates. No significant overall difference in IL-6 level change was found among full, partial and non-users. However, in severely obese patients (body mass index ≥ 35), a significant increase in IL-6 levels during the 2-year period was found in partial and non-users, compared to no change in full users. Results were attenuated in a smaller propensity score matched subsample, although similar trends were observed. No differences were found in soluble IL-6 receptor levels between full users and non-users, after adjustment for confounders. In conclusion, among untreated obese sleep apnea patients, IL-6 levels increase substantially during 2 years, while adherence to positive airway pressure treatment may prevent further increases in this inflammatory biomarker.
authors.affiliation: Department of Respiratory Medicine and Sleep, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland; Faculty of Medicine, University of Iceland, Reykjavik, Iceland; Center for Sleep and Circadian Neurobiology, Division of Sleep Medicine/Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors.forename: Erna S
authors.initials: ES
authors.lastname: Arnardottir
authors.forename: Diane C
authors.initials: DC
authors.lastname: Lim
authors.forename: Brendan T
authors.initials: BT
authors.lastname: Keenan
authors.forename: Greg
authors.initials: G
authors.lastname: Maislin
authors.forename: Bryndis
authors.initials: B
authors.lastname: Benediktsdottir
authors.forename: Sigurdur
authors.initials: S
authors.lastname: Juliusson
authors.forename: Allan I
authors.initials: AI
authors.lastname: Pack
authors.forename: Thorarinn
authors.initials: T
authors.lastname: Gislason
mesh_terms: D015415:Biomarkers / Q000032:analysis; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007055:Iceland; D015850:Interleukin-6 / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000378:metabolism*; D010349:Patient Compliance / Q000706:statistics & numerical data; D019947:Receptors, Interleukin-6 / Q000032:analysis / Q000378:metabolism; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000378:metabolism / Q000628:therapy*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D019947:Receptors, Interleukin-6
keywords: IL-6; continuous positive airway pressure; inflammation; obesity; obstructive sleep apnea; soluble IL-6 receptor levels