Hyperuricemia Rates Remain High Among U.S. Adults and Senior Citizens Placing Them at Risk for Developing Gout

Newswise — Hyperuricemia rates among the nation’s adults and senior citizens remain substantially high, putting them at greater risk for developing gout, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Atlanta.

Hyperuricemia is an abnormally high level of uric acid in the blood that can lead to gout – a painful and potentially disabling form of arthritis that has been recognized since ancient times. Initial symptoms of gout usually consist of intense episodes of painful swelling in single joints, most often in the feet (especially the big toe). Gout occurs when excess uric acid (a normal waste product) accumulates in the body, and needle‐like crystals deposit in the joints. This may happen because either uric acid production increases or, more often, the kidneys are unable to remove uric acid from the body adequately.

Previous studies have confirmed that there is a direct link between serum urate levels and the risk of gout, making serum levels an accurate indicator of how to monitor the disease. Based on this information, researchers recently estimated the increasing trend of hyperuricemia among adults and senior citizens in the United States.

They reviewed National Health and Nutrition Examination Survey (a group of surveys used to assess the health and nutrition of American adults and children) data from 1999-2008 and analyzed 24,693 participants who were at least 20 years old – of which 11,816 were men and 12,877 were women. Data was used to estimate the average serum urate level and prevalence of hyperuricemia (defined, for this study, as having serum urate level greater than 7.0mg/dL in men and greater than 5.7 mg/dL in women) among both gender and age groups and was compared to U.S. population estimates from the Census Bureau. Participant blood samples were also collected—during home interviews or doctor examinations—and tested for blood uric acid levels.

The researchers found that an estimated 31.9 million (20.1 percent) U.S. adults have hyperuricemia. More specifically, they also noted hyperuricemia among 16.1 million men and 15.8 million women. They also found that the prevalence of hyperuricemia increased with age – with those participants ages 20 to 29 years being at a lower prevalence than those who are 80 years or older. Moreover, the study determined that prevalence of hyperuricemia among U.S. adults age 65 and older to be 8.4 million, or 31.3 percent of the population.

“These findings from the latest nationally representative sample of U.S. adults suggest that the prevalence of hyperuricemia is substantial, particularly among older individuals,” explains Yanyan Zhu, PhD; research assistant professor at the Boston University School of Medicine and an investigator in the study. “This burden could be explained by recent increase in obesity and associated conditions (such as metabolic syndrome and hypertension) as these conditions can raise uric acid levels,” says Dr. Zhu, whose research team also recently completed a study showing that gout rates—and related cases of hyperuricema—have increased over the past two decades. This study will also be presented at this ACR’s Annual Scientific Meeting this week.

The American College of Rheumatology is an international professional medical society that represents more than 8,000 rheumatologists and rheumatology health professionals around the world. Its mission is to advance rheumatology. The ACR/ARHP Annual Scientific Meeting is the premier meeting in rheumatology. For more information about the meeting, visit www.rheumatology.org/education or join the conversation on Twitter by using the official hashtag: #ACR2010.

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Editor’s Notes: Yanyan Zhu, PhD will present this research during the ACR Annual Scientific Meeting at the Georgia World Congress Center at 2:45 PM on Tuesday, November 9 in Room A 410. Dr. Zhu will be available for media questions and briefing at 8:30 AM on Wednesday, November 10 in the on-site press conference room, B 212.

Learn more about living well with rheumatic disease as well as rheumatologists and the role they play in health care.

Presentation Number: 1363Prevalence of Hyperuricemia in the US General Population: the National Health and Nutrition Examination Survey (NHANES) 1999-2008

Yanyan Zhu, PhD (Boston University School of Medicine, Boston, MA)Hyon Choi, MD, DrPh. (Boston University School of Medicine, Boston, MA)

Body: Objective: There is a direct causal relation between serum urate (sUA) levels and the risk of gout. Thus, the population's sUA levels are accurate surrogate indicators for the scope of the disease burden of gout in the population. Our objective was to estimate the trends of sUA levels and prevalence of hyperuricemia based on a recent, nationally representative sample of US men and women (NHANES 1999-2008).

Methods: Using data from 24,693 participants (11,816 men and 12,877 women) aged 20 years and older from NHANES 1999-2008, we estimated overall, gender-specific, and age-specific mean sUA levels and prevalence of hyperuricemia. sUA was measured by oxidization with the specific enzyme uricase to form allantoin and hydrogen peroxide, using participants' blood samples collected during home interview or examination session. We used an NHANES definition of hyperuricemia (sUA level >7.0 mg/dL in men and >5.7 mg/dL in women). We estimated the number of people with hyperuricemia by applying our prevalence estimates to the corresponding US population estimates from the Census Bureau.

Results: The overall prevalence of hyperuricemia among US adults was 20.1%, which corresponded to an estimated 31.9 million individuals with hyperuricemia. The prevalence of hyperuricemia among men was 21.1% (16.1 million) and 19.2% (15.8 million) among women. The overall mean sUA level was 5.41 mg/dL (95% CI, 5.38 to 5.44 mg/dL). The mean sUA level was 6.10 mg/dL (95% CI, 6.06 to 6.14 mg/dL) among men and 4.77 mg/dL (95% CI, 4.73 to 4.80 mg/dL) among women. The prevalence of hyperuricemia increased with age, ranging from the lowest (15.6%, 4.5 million) in individuals aged 20 to 29 years to the highest (36.7%, 2.4 million) in individuals aged 80 years or older. The prevalence of hyperuricemia among individuals aged 65 years or older was 31.3%, which corresponded to an estimated 8.4 million US adults with hyperuricemia (Table). Conclusions: These findings from the latest nationally representative sample of US adults in NHANES 1999-2008 suggest that the prevalence of hyperuricemia is substantial, particularly among older individuals.Disclosure: Yanyan Zhu, nothing to disclose; Bhavik Pandya, Takeda Pharmaceuticals International, Inc.: Employment (full or part-time); Hyon Choi, Takeda Pharmaceuticals International, Inc.: Consulting fees.

View press release with full abstract at www.rheumatology.org