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]).

Conclusion: Our randomized controlled trial has shown no significant reduction in serum urate following 3months treatment with therapeutic or placebo CPAP.

Keywords: CPAP; Gout; Hyperuricemia; OSA; Type 2 diabetes mellitus; Urate.