Gout, urate-lowering therapy, and uric acid levels among adults in the United States

Abstract

Objective: Evidence strongly suggests that delivery of gout care is suboptimal. The 2012 American College of Rheumatology (ACR) guidelines emphasize a serum uric acid (SUA) target of <6 mg/dl when utilizing urate-lowering therapy (ULT). However, the proportion and characteristics of Americans with gout receiving ULT, or with a ULT indication, who are achieving this target is unknown.

Methods: We identified US adults with gout receiving ULT, and those with an indication for ULT, using the National Health and Nutrition Examination Surveys from 2007-2010. Using the ACR guidelines, a ULT indication comprised chronic kidney disease (CKD) stage 2-5, a history of nephrolithiasis, or current ULT use. Demographic and clinical factors associated with an SUA ≥6 mg/dl were determined using Poisson regression.

Results: In 2007-2010, an estimated 4.5 million US adults with gout had an indication for ULT; two-thirds had an SUA ≥6 mg/dl. In adjusted analyses among those with gout and CKD or nephrolithiasis, those age ≥70 years were less likely (prevalence ratio [PR] 0.77, 95% confidence interval [95% CI] 0.61-0.97) to have an SUA ≥6 mg/dl. Regarding those taking ULT, hypertension was related to a reduced prevalence (PR 0.51, 95% CI 0.30-0.87), whereas diabetes mellitus (PR 1.42, 95% CI 1.06-1.90) and obesity (PR 1.74, 95% CI 1.19-2.56) were each associated with a higher prevalence of an SUA value ≥6 mg/dl.

Conclusion: Half of all Americans with gout receiving ULT, and two-thirds with an indication for ULT, have an SUA above target. This study furnishes a meaningful baseline for assessing the effectiveness of the ACR guidelines in future years.

Figure 1

Flow chart representing the prevalence and population estimate in millions (mil) of (1) total gout; (2) gout with an indication for urate-lowering therapy (ULT) according to guidelines established by the American College of Rheumatology, i.e., chronic kidney disease (CKD) stage 2–5 or nephrolithiasis, or current ULT use; and (3) gout with an indication for ULT and a uric acid ≥ 6 mg/dl. Estimates with black lettering represent the entire US population, while estimates in gray lettering represent a proportion of gout or a subpopulation of gout. Note some participants had more than one indication for ULT such that the three categories depicted in the third row of the figure are not mutually exclusive. Modest discrepancies in percentage values are due to rounding.