title: Continuous positive airway pressure reduces postprandial lipidemia in obstructive sleep apnea: a randomized, placebo-controlled crossover trial.
abstract: BACKGROUND
  Dyslipidemia is common in Obstructive Sleep Apnea (OSA). Postprandial lipidemia (PPL) is a strong marker of cardiovascular risk. Evidence that OSA treatment improves PPL is lacking.
  
  
  OBJECTIVE
  To investigate the effect of continuous positive airway pressure (CPAP) treatment on postprandial lipidemia (PPL) in patients with obstructive sleep apnea (OSA) in the upper moderate or severe range.
  
  
  METHODS
  In this randomized, placebo-controlled crossover trial, we compared the effects of 2 months each of therapeutic and placebo CPAP on PPL.
  
  
  RESULTS
  PPL was determined from the area under the 24-hour triglyceride concentration curve (TAG-AUC(24)) using seven blood samples drawn across both the wake and sleep periods. Secondary outcomes were the difference in other 24-hour lipid profiles. Thirty-eight eligible patients were randomly assigned to a treatment order and 29 patients completed the trial. CPAP reduced PPL compared with placebo with a mean TAG-AUC(24) difference of -357 mmol/L/d (95% confidence interval [CI], -687.3 to -26.8; P = 0.035). During both the CPAP and placebo studies, TAG levels peaked during both wakefulness (2:00 p.m.) and sleep (3:00 a.m.). Both peaks were lower during CPAP than placebo: 2:00 p.m., -0.49 mmol/L (95% CI, -0.74 to -0.24; P < 0.0005) and 3:00 a.m., -0.40 mmol/L (95% CI, -0.65 to -0.15; P = 0.002). Moreover, mean 24-hour total cholesterol was -0.19 mmol/L lower on CPAP (95% CI, -0.27 to -0.11; P < 0.00001).
  
  
  CONCLUSIONS
  This randomized trial demonstrated that treatment of severe OSA with CPAP improves postprandial TAG and total cholesterol levels. These effects may reduce the risk for cardiovascular events. The results imply that the association between OSA and cardiovascular disease may, in part, be caused by direct effects on dyslipidemia. Clinical trial registered with the Australian and New Zealand Clinical Trials Registry at www.anzctr.org.au (ACTRN 12605000066684).
authors.affiliation: Sleep and Circadian Research Group, Woolcock Institute of Medical Research, Sydney, New South Wales, Australia. craig.phillips@sydney.edu.au
authors.forename: Craig L
authors.initials: CL
authors.lastname: Phillips
authors.forename: Brendon J
authors.initials: BJ
authors.lastname: Yee
authors.forename: Nathaniel S
authors.initials: NS
authors.lastname: Marshall
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Liu
authors.forename: David R
authors.initials: DR
authors.lastname: Sullivan
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Grunstein
mesh_terms: D002318:Cardiovascular Diseases / Q000209:etiology / Q000517:prevention & control*; D045422:Continuous Positive Airway Pressure; D018592:Cross-Over Studies; D050171:Dyslipidemias / Q000150:complications / Q000209:etiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D009517:New South Wales; D019518:Postprandial Period / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000628:therapy; D014280:Triglycerides / Q000097:blood*
chemical_list: D014280:Triglycerides