Obesity has long been considered a risk factor for gout, but new findings confirm that the risk starts climbing when people are merely overweight - and that more Americans are developing gout these days.
Historically, research into gout has mainly used data on white men. The new study, reported online in Arthritis Care & Research, looked at a broader swath of Americans.
"Gout is not just a disorder of men. It's not just a disorder of whites," said senior researcher Dr Allan C Gelber, of Johns Hopkins University School of Medicine in Baltimore.
What the research showed
Estimating from government health survey data on more than 28 000 individuals, Dr Gelber's team found that between 1988 and 1994, about 2.6% of US adults had gout - corresponding to 4.7 million people.
Between 2007 and 2010 that figure was almost 3.8%, corresponding to about 8.1 million adults.
Regardless of the time period, though, obese Americans had the highest gout rates.
In the later years, almost 5.5% of moderately obese adults had gout, as did 7% of severely obese people - compared with 1.6% of normal-weight adults and 3.4% of overweight people.
"The increase in gout risk applies to people who are overweight as well," Dr Gelber said. "It's not that there's a threshold where it goes up only if you're obese."
Women were less likely than men to have gout at either time period, but excess weight was linked to a similar impact on their risk.
Weight also seemed to carry as much importance for African Americans and Mexican Americans as it did for whites. There weren't enough data to single out other ethnic groups.
As for why weight affects gout risk, there are a couple of theories. Obesity, as well as high blood pressure, diabetes and kidney disease can boost the body's production of uric acid or slow the clearance of it.
But based on the current findings, uric acid and other health conditions do not fully explain why overweight people have a higher gout risk. "They're part of the story, but not the whole story," Dr Gelber said. Researchers are still trying to figure out the other reasons for the weight-gout connection, he noted.
He and his colleagues estimate that for someone who is 5 feet, 9 inches tall, every seven pounds of extra weight corresponds to a 5% increase in gout risk.
Dr Gelber said gout should be on doctors' minds when an overweight patient complains of joint pain. That's important, he said, because there is a difference in the treatments for gout and osteoarthritis.
(Reuters Health, August 2012)
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