title: Serum urate levels are unchanged with continuous positive airway pressure therapy for obstructive sleep apnea: a randomized controlled trial.
abstract: OBJECTIVE
  Hyperuricemia is associated with the presence and severity of obstructive sleep apnea (OSA). Previous work has shown that treatment of OSA with continuous positive airway pressure (CPAP) therapy reduces urinary uric acid excretion and serum urate, but there has been no previous randomized controlled investigation on the effects of CPAP therapy on serum urate; we aimed to assess this association.
  
  
  METHODS
  Serum urate was measured in samples from participants of a previously published randomized controlled trial. Samples were taken at baseline and after 3months from men with known type 2 diabetes mellitus (T2DM) and newly diagnosed OSA, randomized to receive either therapeutic (n=19) or placebo (n=19) CPAP for 3months.
  
  
  RESULTS
  Both groups were well matched at baseline, with no significant difference in age, body mass index (BMI), glycosylated hemoglobin (HbA1c), or oxygen desaturation index (ODI). There was no significant difference in therapeutic or placebo CPAP usage. There was no significant difference in urate levels between groups at baseline (362μmol/L [standard deviation {SD}, 96] vs 413μmol/L [SD, 91] [reference range, 110-428μmol/L]) or at 3months. Baseline urate did not correlate with ODI, BMI, or HbA1c. The mean change in urate at 3months did not significantly differ between treatment groups (-7.6μmol/L [SD, 35.9] vs -6.2μmol/L [SD, 46.2]) (P=.9; [95% confidence interval, -28.7 to +25.9]).
  
  
  CONCLUSIONS
  Our randomized controlled trial has shown no significant reduction in serum urate following 3months treatment with therapeutic or placebo CPAP.
authors.affiliation: Newcastle Regional Sleep Service, Newcastle upon Tyne Hospitals NHS Foundation Trust, UK. Electronic address: ben_prudon@doctors.org.uk.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Prudon
authors.forename: Edward
authors.initials: E
authors.lastname: Roddy
authors.forename: John R
authors.initials: JR
authors.lastname: Stradling
authors.forename: Sophie D
authors.initials: SD
authors.lastname: West
mesh_terms: D000368:Aged; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications; D006073:Gout / Q000150:complications / Q000378:metabolism; D006801:Humans; D033461:Hyperuricemia / Q000453:epidemiology* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010919:Placebos; D015995:Prevalence; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology / Q000378:metabolism / Q000628:therapy; D016896:Treatment Outcome; D014527:Uric Acid / Q000097:blood*
chemical_list: D010919:Placebos; D014527:Uric Acid
keywords: CPAP; Gout; Hyperuricemia; OSA; Type 2 diabetes mellitus; Urate