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 needleâlike 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.