Rheumatoid arthritis (RA) patients can develop gout, say researchers who believe changes in treatment and obesity may explain why the comorbidity is now occurring.
The study findings, which go against perceived wisdom, were reported at the American College of Rheumatology/Association of Rheumatology Health Professionals Annual Meeting in Washington DC.
In all, 813 patients diagnosed with RA between 1980 and 2007 were followed up until April 2011, for an average of 12 years, as part of the Rochester Epidemiology Project.
During this time, 22 patients developed gout, defined as the presence of monosodium urate crystals in synovial fluid or meeting 1977 American Rheumatism Association clinical criteria. The big toe was the most common site affected by gout, affecting 12 of the group.
The 25-year incidence of gout was 5.3% using clinical criteria and 1.3% using crystal findings. The age- and gender-adjusted incidence of gout on January 1 2008 was 1.9% compared with the expected age- and gender-adjusted incidence of 5.2% from US population data, the researchers note.
But gout was a significant 5.6 times more common in patients diagnosed with RA between 1995 and 2007 than in patients diagnosed between 1980 and 1994.
Presenting author Eric Matteson (Mayo Clinic, Rochester, Minnesota, USA) commented in a press release that the use of aspirin for RA may have protected patients against gout in the past, but that this is no longer a commonly used treatment.
Of note, gout was significantly associated with being male (hazard ratio [HR]=3.18), older age (HR=1.5 per 10-year increase), and obesity (HR=3.5), whereas a diagnosis of erosive joint RA disease reduced the risk for gout (HR=0.24).
"It is probably true that flares of [RA] in some cases might have actually been flares of gout, and that the gout wasn't diagnosed; it wasn't realized that it was a coexistent problem," said Matteson.
"Awareness that gout does exist in patients with [RA] hopefully will lead to better management of gout in those patients."
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