Uric acid in the blood may help to predict whether people will go on to develop gout.
INTRODUCTION
Gout is a very common condition, affecting 0.08% of the global population.1 The symptoms tend to flare every so often, developing over a few hours and causing severe pain in the joints. It is caused by deposits of crystals of a substance called uric acid (urate) in the joints, which leads to inflammation.
WHAT DID THE AUTHORS HOPE TO FIND?
The authors hoped to find out why some people with high levels of uric acid in their blood develop gout whilst others do not.
WHO WAS STUDIED?
The study included 25 people with very high uric acid levels but no joint problems, and compared them to 33 people diagnosed with gout.
HOW WAS THE STUDY CONDUCTED?
This was a cross-sectional study, which means that the researchers simply observed and recorded information about the people in the study. A study of this type is used to compare different groups of people at a single point in time, without changing any variables.
All participants had a scan of their feet taken called a dual energy CT scan. This is a new type of scan that allows the researchers to look at uric acid crystals. The authors then analysed whether uric acid crystals were present, and also measured the volume of the crystals using automated computer software.
WHAT WERE THE MAIN FINDINGS OF THE STUDY?
The study found that about a quarter of people with very high levels of uric acid in their blood (but no joint problems) had uric acid crystals present in the scans of their feet. In contrast, the scans showed that there were uric acid crystals in over 80% of the people with gout, even in those who had only recently developed the disease. The study also found that the volume of uric acid crystals was also much higher in the people with gout, with almost thirty-times the volume recorded in people with gout compared to those without.
ARE THESE FINDINGS NEW?
Yes, this is the first time that the uric acid crystal volumes have been compared between people with gout and those with high uric acid levels but no joint problems.
HOW RELIABLE ARE THE FINDINGS?
There are limitations in the conclusions that can be drawn from cross-sectional studies. These studies offer a snapshot of a single point in time, and that means they do not consider what happens before or after the snapshot is taken. This may limit what we can say about the results.
Additionally, it is possible that the method of scanning used may not pick up very small uric acid crystal deposits, and this may have affected the results. But the authors are confident that their findings are reliable.
WHAT DO THE AUTHORS PLAN ON DOING WITH THIS INFORMATION?
At this stage, it is not known whether people with high uric acid levels but no joint symptoms are more likely to develop gout in the future if the dual energy CT scan shows evidence of uric acid crystals in their feet. The authors are planning long-term follow-up studies of people with high blood uric acid levels to address this question.
WHAT DOES THIS MEAN FOR ME?
We know that uric acid is linked to the risk of developing gout. This study suggests that a certain amount, or threshold, of uric acid crystals may be needed in people with high blood uric acid levels before gout develops. Medication is not recommended for treating high blood uric acid levels in people who do not have gout. If you do have high uric acid levels but no gout it may be worthwhile talking to your doctor about ways to re \duce your levels, as this may reduce the risk of developing gout in the future.
ADDITIONAL REFERENCE
1 Smith E. et al. The global burden of gout: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014;73:968–74.
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Date summary prepared: May 2015
Summary based on research article published on: 30 January 2015
From: Dalbeth, N. et al. Urate crystal deposition in asymptomatic hyperuricaemia and symptomatic gout: A dual energy CT study. Ann Rheum Dis 2015;74:908–11. doi:10.1136/annrheumdis-2014- 206397
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