Nov. 10, 2010 (Atlanta) -- The latest figures on gout are in, and they’re disappointing, researchers say. Following a doubling of cases of the painful and often disabling arthritic condition from the 1960s to the 1990s, gout rates continued to rise through 2008, the most recent year studied.
In a national health survey conducted in 2007 and 2008, 8.3 million Americans reported they had been told by their doctor they have gout.
That corresponds to 3.9% of U.S. adults -- and represents a substantial rise from the 2.7% prevalence rate reported in the late 1980s and early 1990s, says Yanyan Zhu, PhD, a research assistant professor in clinical epidemiology at the Boston University School of Medicine.
The increase was primarily due to rising rates among men -- from about 4% in the earlier time period to 6% in the later -- and older people, she tells WebMD.
The gout rate was 7% among Americans aged 60 to 79 in the early 1990s, compared with 9% by 2008. Among those aged 80 and older, the rate more than doubled, from 6% to 13% over the nearly 20-year time span.
Zhu reported the findings here at the American College of Rheumatology's annual meeting.
The Painful Effects of Gout
Gout occurs when too much uric acid -- a normal by-product of DNA metabolism -- builds up in the body. This leads to crystal formation. The crystals deposit in the joints, where they can wreak havoc.
"Patients typically have sudden-onset attacks, in which one or more joints become red, inflamed, and angry looking. This is accompanied by what some patients say is the worst pain they have ever experienced," says John S. Sundy, MD, PhD, a gout expert at Duke University Medical Center in Durham, N.C.
"Attacks of this inflammatory arthritis last three to 10 days, and at first, there can be months, even years, between attacks. As time goes on, flare-ups become more frequent -- and more painful," says Sundy, who moderated a news briefing to discuss the findings.
Pre-Gout Condition on the Rise
For the new study, Zhu and colleagues compared the results of two large-scale surveys of American adults, with specific regard to the question of whether a doctor had ever told them they had gout.
The earlier National Health and Nutrition Examination Survey (NHANES), conducted between 1988 and 1994, involved 18,825 Americans aged 20 and over, 10,009 of whom were women.
The later NHANES survey, carried out in 2007 and 2008, involved 5,707 adults, 2,910 of whom were women.
In addition to the 1.2% increase in gout rates from the earlier to the later time period, the researchers found that the rate of the pre-gout condition known as hyperuricemia is also on the rise.
Over the 20-year study period, the percentage of Americans with hyperuricemia -- an abnormally high level of uric acid in the blood that can sometimes lead to gout -- rose from 18% to 21%, Zhu says.
Obesity and Gout
Zhu says she believes the epidemic of obesity and rising rates of high blood pressure among Americans are largely to blame for the escalating numbers of people with both conditions.
Better management of these risk factors could help stem the tide, she says.
Sundy, who says that he was "disappointed, but not surprised, by the findings," says that many questions remain. "We don't know whether high uric acid contributes to obesity and hypertension, or whether obesity and hypertension contribute to high uric acid, or they are just birds of a feather that travel together.”
Sundy tells WebMD it is doubtful that increased screening and earlier diagnosis may help explain the rise in gout rates, as some experts have suggested.
"Uric acid levels are no longer a standard measure on panels" given when you have blood drawn during your regular physical exam, he explains. "Now it’s a directed measure if a patient has symptoms or the provider otherwise wants to check."
Routine uric acid screens, which were dropped because they were not believed to add "clinically meaningful" information, should be reinstated, Sundy says.
Longer Lives May Affect Gout Rates
The fact that Americans are living longer may be contributing to rising gout rates, Sundy says. "You rarely see gout in women before menopause. But after menopause, uric acid levels, and the risk of developing gout, increases."
Age is a risk factor for both men and women, he says. "You can go years with hyperuricemia and no symptoms. But at some point, enough uric acid accumulates to have a flare-up of gout, so if you're living longer you are more likely to reach that threshold."
Sundy says the fact that the study relied on patients recalling whether a doctor ever told them they had gout -- a method some say is subject to inaccurate memories -- was not a major drawback. "It's not the gold standard, but it turns out patient reports of doctor diagnoses are pretty accurate and, with such large numbers, not likely to alter the findings."
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.