title: Sleep Related Breathing Disorders and Inflammation - The Missing Link? A Cohort Study Evaluating the Interaction of Inflammation and Sleep Related Breathing Disorders and Effects of Treatment.
abstract: BACKGROUND
  Sleep related breathing disorders (SRBD) are associated with both obesity and systemic inflammation. While the relationship between obesity and SRBD is established, the causality between inflammation and SRBD remains unclear. In this study we investigated the relation between SRBD and C-reactive protein (CRP) as a parameter of inflammation and the influence of SRBD treatment on CRP with additional regard to changes in metabolic and cardiovascular parameters.
  
  
  METHODS
  Polysomnography (PSG) and laboratory data of patients diagnosed with SRBD over a period of 5 years were prospectively collected in a database and retrospectively analysed regarding the association of SRBD (according to apnoea-hypopnoea- index (AHI), duration of events and extent of desaturation) to CRP, blood pressure, cholesterol, fasting plasma glucose, HbA1c, quality of life measured via a visual analogue scale (VAS 0-100%), and the effects of SRBD therapy on these parameters.
  
  
  RESULTS
  716 patients were included in the study, 171 with mild SRBD (AHI ≥5 to <15/h), 209 with moderate SRBD (AHI 15 to <30/h), 336 with severe SRBD (AHI ≥30/h). Results according to severity of SRBD. Severe SRBD was significantly associated with elevated levels of CRP (3.7 [1.8-7.0] mg/l, vs. moderate (p = 0.001), and mild SRBD (p<0.001), and higher prevalence of hypertension as compared to moderate and mild SRBD (p<0.001, respectively). Results in highly successful treatment. If SRBD treatment was highly successful (AHI <5/h), CRP and quality of life improved significantly (p = 0.001 and p = 0.002), as did blood pressure (p<0.001 for systolic and diastolic values), although BMI increased (p<0.001). Results in partially successful treatment. If success was defined as reduction of AHI of ≥50%, CRP also decreased (p<0.001), as did blood pressure (p<0.001). Again, BMI increased (p<0.001).
  
  
  CONCLUSIONS
  This is the first study to show an association of SRBD and CRP independently of BMI in a large cohort. The SRBD therapy-induced CRP decrease was not associated with BMI changes or metabolic changes but rather with the magnitude of AHI improvement.
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Medical University, Graz, Austria.
authors.forename: Natascha
authors.initials: N
authors.lastname: Troester
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Medical University, Graz, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Palfner
authors.affiliation: Institute for Medical Informatics, Statistics and Documentation, Medical University, Graz, Austria.
authors.forename: Erich
authors.initials: E
authors.lastname: Schmidberger
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Medical University, Graz, Austria; Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.
authors.forename: Horst
authors.initials: H
authors.lastname: Olschewski
authors.affiliation: Institute for Medical Informatics, Statistics and Documentation, Medical University, Graz, Austria; Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Avian
mesh_terms: D000368:Aged; D015415:Biomarkers; D001794:Blood Pressure; D015992:Body Mass Index; D002097:C-Reactive Protein; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications; D007249:Inflammation / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D011788:Quality of Life; D012720:Severity of Illness Index; D012737:Sex Factors; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000175:diagnosis / Q000378:metabolism* / Q000628:therapy; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein