title: Cardiometabolic changes after continuous positive airway pressure for obstructive sleep apnoea: a randomised sham-controlled study.
abstract: OBJECTIVE
  Impaired insulin sensitivity (ISx), increased visceral abdominal fat (VAF) and liver fat are all central components of the metabolic syndrome and characteristics of men with obstructive sleep apnoea (OSA). The reversibility of these observed changes with continuous positive airway pressure (CPAP) treatment in men with OSA has not been systematically studied in a randomised sham-controlled fashion.
  
  
  METHODS
  65 men without diabetes who were CPAP naïve and had moderate to severe OSA (age=49±12 years, apnoea hypopnoea index (AHI)=39.9±17.7 events/h, body mass index=31.3±5.2 kg/m(2)) were randomised to receive either real (n=34) or sham (n=31) CPAP for 12 weeks. At 12 weeks, all subjects received real CPAP for an additional 12 weeks.
  
  
  RESULTS
  Main outcomes were the change at week 12 from baseline in VAF, ISx and liver fat. Other metabolic outcomes were changes in the disposition index, total fat, and blood leptin and adiponectin concentrations. The AHI was lower on CPAP compared with sham by 33 events/h (95% CI-43.9 to -22.2, p<0.0001) after 12 weeks. There were no between-group differences at 12 weeks in VAF (-13.0 cm(3), -42.4 to 16.2, p=0.37), ISx (-0.13 (min(-1))(μU/ml))(-1), -0.40 to 0.14, p=0.33), liver fat (-0.5 cm(3), -3.8 to 2.7, p=0.74) or any other cardiometabolic parameter. At 24 weeks, ISx (3.2×10(4) (min(-1))(μU/ml))(-1), 0.9×10(4) to 6.0×10(4), p=0.009), but not VAF (-1.4 cm(3), -19.2 to 16.4, p=0.87) or liver fat (-0.2 Hounsfield units, -2.4 to 2.0, p=0.83) were improved compared with baseline in the whole study group.
  
  
  CONCLUSIONS
  Reducing visceral adiposity in men with OSA cannot be achieved with CPAP alone and is likely to require weight-loss interventions. Longer-term effects of CPAP on other cardiometabolic markers such as ISx require further investigation to fully examine time dependencies.
  
  
  BACKGROUND
  ACTRN12608000301369.
authors.affiliation: Endocrine and Cardiometabolic Research Group, Woolcock Institute of Medical Research, University of Sydney, Glebe, Australia.
authors.forename: Camilla M
authors.initials: CM
authors.lastname: Hoyos
authors.forename: Roo
authors.initials: R
authors.lastname: Killick
authors.forename: Brendon J
authors.initials: BJ
authors.lastname: Yee
authors.forename: Craig L
authors.initials: CL
authors.lastname: Phillips
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Grunstein
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Liu
mesh_terms: D050153:Abdominal Fat / Q000378:metabolism; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure; D004311:Double-Blind Method; D005234:Fatty Liver / Q000150:complications* / Q000517:prevention & control; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications* / Q000517:prevention & control; D008875:Middle Aged; D017286:Polysomnography; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome