Uric Acid Levels May Influence Mortality in OSA

TOPLINE:

High levels of serum uric acid (SUA) were significantly associated with a higher risk for all-cause mortality, but low levels were linked to a higher risk for both all-cause mortality and cardiovascular disease (CVD) mortality in adults with obstructive sleep apnea (OSA).

METHODOLOGY:

• The researchers used data from four cycles of the National Health and Nutrition Examination Survey — 2005-2006, 2007-2008, 2015-2016, and 2017-2018; the study population included 5584 individuals with OSA.

• The primary outcomes were all-cause mortality and CVD mortality, and the researchers used a restricted cubic splines (RCS) model to assess the relationships between SUA and mortality.

• Measures of SUA were divided into quintiles: Q1 (<4.4 mg/dL), Q2 (4.4-5.2 mg/dL), Q3 (5.2-5.899 mg/dL), Q4 (5.9-6.79 mg/dL), and Q5 (≥6.8 mg/dL); Q4 served as the reference.

TAKEAWAY:

• A total of 537 deaths occurred in the study population; 108 of these were attributed to CVD.

• The adjusted hazard ratios for SUA quintiles Q1, Q2, Q3, Q4, and Q5 for all-cause mortality were 1.33, 1.53, 1.18, 1.00 (reference), and 1.51, respectively (P = .03 for trend) and for CVD mortality were 1.12, 2.40, 1.45, 1.00 (reference), and 1.77, respectively (P = .98 for trend).

• Using the RCS model, the researchers found a U-shaped association between SUA and all-cause mortality overall; the inflection point was 5.83 mg/dL, and the association was consistent across subgroups.

• Among patients with OSA aged 60 years and older, the RCS model showed a J-shaped association between SUA levels and mortality, with an inflection point of 6.324 mg/dL; when uric acid levels were below 6.32 mg/dL, each 1 mg/dL increase was associated with a 25% decrease in mortality.

IN PRACTICE:

More research is needed to determine the causal relationship between SUA levels and all-cause mortality and CVD mortality; however, "Monitoring uric acid levels may serve as an important tool for predicting and preventing chronic diseases and premature death," the researchers said.

SOURCE:

The lead author on the study was Zhe Yang, Zhejiang University School of Medicine, Zhejiang, China. The study was published online in Nature Scientific Reports on November 10, 2023.

LIMITATIONS:

The diagnosis of OSA was based mainly on medical history, which may have introduced bias, and the study population included only individuals in the United States, so the results may not generalize to other countries.

DISCLOSURES:

The study received no outside funding. The researchers had no financial conflicts to disclose.