Gout prevalence remained significant but stable in recent years among U.S. adults, yet only a minority of patients with this painful disorder are receiving urate lowering therapy, analysis of a nationally representative sample showed.
Data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2016 indicated that the overall prevalence of gout in the U.S. remained at 3.9% after having doubled from the 1960s to 1990s, according to Hyon K. Choi, MD, DPH, of Harvard Medical School and Massachusetts General Hospital in Boston, and colleagues.
Rates of urate lowering therapy also were similar during the years 2007 to 2016, at only about one-third of patients, the researchers reported online in Arthritis & Rheumatology.
Previous analyses of NHANES data had tracked the rising rates of gout and hyperuricemia in earlier decades, but it has not been clear whether these trends and related risk factors have continued. So Choi and colleagues analyzed the five most recent NHANES cycles (2007-2008, 2009-2010, 2011-2012, 2013-2014, and 2015-2016), which included 14,161 men and 15,040 women ages 20 and older.
Hyperuricemia was defined as a level of serum urate above 7 mg/dL for men and 5.7 mg/dL for women. Alternative definitions included levels above 6 mg/dL, which is the standard target for gout treatment, and above 7 mg/dL, which represents the supersaturation point of serum urate.
In the 2015-2016 cycle, the mean age was 48, slightly fewer than half of participants were men, and two-thirds were non-Hispanic whites. The prevalence of gout was 5.2% for men and 2.7% for women, with highest rates being seen among those 80 and older.
During that cycle, hyperuricemia using the standard definition was 20.2% among men and 20% among women. Using the 7 mg/dL cutoff, the rates were 20.2% for men and 4.2% for women, while for the 6 mg/dL cutoff, the rates were 49.5% and 16.4%, respectively.
The overall mean serum urate level was 5.39 mg/dL (95% CI 5.34-5.45), while mean levels were 6.04 mg/dL and 4.79 mg/dL for men and women, respectively.
During the years 2007-2014 (the latest year with available data), the prevalence of urate-lowering therapy use was 32.8%, with allopurinol representing 95% of prescriptions.
Among individuals with gout, factors associated with a greater likelihood of use of urate lowering therapy were male sex, stage 3 chronic kidney disease, and obesity.
Also during the years 2007-2014, the prevalence of patients achieving the target serum urate level below 6 mg/dL was 37.7% (95% CI 34-41.6). For men, the prevalence was 31.6% (95% CI 27.1-36.4), while for women, it was higher, at 51.8% (95% CI 43.3-60.2).
Mean serum urate levels were 5.78 mg/dL for patients on urate lowering therapy compared with 6.92 mg/dL for those not on therapy, and after adjustment for multiple factors including age, sex, body mass index, blood pressure, glomerular filtration rate, use of thiazide diuretics, and alcohol intake, those on urate lowering therapy had a serum urate level 1.40 mg/dL lower than those not on treatment.
Accordingly, patients with gout receiving urate lowering therapy were more than six times more likely to achieve the target urate level below 6 mg/dL than nonusers (OR 6.21, 95% CI 3.93-9.81).
In addition, factors associated with a more than 50% lower odds for reaching the target urate level included male sex, chronic kidney disease of stage 3 or higher, obesity, and use of thiazide diuretics. “Given the well established role of serum urate levels for gout flares, these data suggest a potential need for more aggressive therapy among these subgroups,” the researchers observed.
In further discussing their findings, they noted, “The current stability of gout and hyperuricemia prevalences overall may be related to the plateauing trends of chronic kidney disease and hypertension in the U.S. over a similar time period, given their strong associations with gout and hyperuricemia.”
As to the persistently low rates of the use of urate lowering therapy for patients with gout, they pointed out barriers including patient and provider knowledge gaps and inadequate recognition that the disorder is now considered curable. Moreover, it is not yet apparent whether the use of urate lowering therapy will decline further following recent gout care guidelines from the American College of Physicians that do not recommend a treat-to-target approach for serum urate, unlike guidelines from the American College of Rheumatology and the European League Against Rheumatism.
One study limitation was the self-report of gout.
The study was supported by Ironwood and Horizon.
The authors reported financial relationships with Ironwood, Horizon, Takeda, Kowa, Selecta, Pfizer, and SOBI.