Modern imaging techniques such as ultrasound may help to diagnose and classify gout.
INTRODUCTION
Gout is a very common condition. 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. Imaging techniques are a non-invasive way to be able to look inside the joint to see if there are crystal deposits. There are several imaging techniques available, including MRI (magnetic resonance imaging), ultrasound, radiography and CT scans and double energy CT scans (DECT). These give doctors a picture of the inside of the joint.
WHAT DID THE AUTHORS HOPE TO FIND?
The authors wanted to know whether imaging techniques can give a reliable and accurate diagnosis of gout. They also wanted to look at how imaging techniques compared to testing the joint fluid for crystals, which is currently the best way to confirm a diagnosis and involves taking some fluid from the joint with a fine needle. The authors hoped that this study would support a new way to diagnose and classify gout.
WHO WAS STUDIED?
The authors looked at studies that had already been published. These all reported the use of imaging techniques in people referred with joint swelling. All studies had gout confirmed by testing for uric acid crystals in the joint fluid.
HOW WAS THE STUDY CONDUCTED?
A systematic review aims to identify all the published evidence on a particular topic and draw it together into one summary. This paper also included a meta-analysis, which means that statistical analyses have been performed on the results in order to be sure that the conclusions being drawn are meaningful. The authors used major electronic databases and clinical trial registries to search for trials and studies that reported studies of imaging techniques in people with gout. Each study also had to have a control group of people who did not have gout to compare against. The search gave a long list of 1171 articles. Of these 11 had the correct type of information and were included in the review.
WHAT WERE THE MAIN FINDINGS OF THE STUDY?
The authors found that both ultrasound and DECT scans are accurate and reliable for diagnosing gout.
ARE THESE FINDINGS NEW?
The study did have some unique elements, but the findings are not new as this is a summary of the available data and evidence that has already been published elsewhere.
HOW RELIABLE ARE THE FINDINGS?
There are several limitations in this study. Some of the studies included patients who had had gout for a long time, which can make it seem like the imaging tests perform better. Additionally, there was not consistency between the various studies included and many of them were very small. An important part of the study was to work out if imaging techniques can diagnose gout as accurately as testing the joint fluid for uric acid crystals. It was not clear in all the studies included whether imaging techniques were performed before or after the joint fluid test, and this may have affected the results.
WHAT DO THE AUTHORS PLAN ON DOING WITH THIS INFORMATION?
These results were used to decide whether or not to include DECT scans and ultrasound in the new gout classi- fication criteria developed by ACR and EULAR.1 More studies are planned to look at the use of ultrasound in normal patients in the real world.
WHAT DOES THIS MEAN FOR ME?
These results will support the use of imaging techniques in people suspected of having gout. If you have symptoms of gout, your doctor may refer you for an ultrasound or DECT scan. It may mean that it will become easier and quicker for you to receive a diagnosis.
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Date prepared: October 2015
Summary based on research article published on: 10th June 2014
From: Ogdie A, et al. Imaging modalities for the classification of gout: systematic literature review and meta-analysis. Ann Rheum Dis 2015;74:1868–74. doi:10.1136/annrheumdis-2014-205431LaySummary
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