European recommendations for the diagnosis of gout issued
medwireNews: EULAR has issued eight updated evidence-based recommendations to guide the diagnosis of gout.
“Despite effective treatments, gout is still often misdiagnosed and its management remains suboptimal,” say Pascal Richette (Hopital Lariboisiere Centre Viggo Petersen, Paris, France) and co-authors.
They explain that “[n]ew data on imaging and clinical diagnosis have become available since the first EULAR recommendations for the diagnosis of gout in 2006,” which prompted a revision of the guidelines.
The new recommendations were developed by a taskforce from 12 European countries comprising 15 rheumatologists, three experts in epidemiology or methodology, two primary care providers, two patients, and one musculoskeletal radiologist. Richette and team used a systematic review and a Delphi consensus approach to form their recommendations.
As reported in the Annals of the Rheumatic Diseases, the authors propose a three-step approach for the diagnosis of gout. They say that the first step should be to search for monosodium urate crystals in synovial fluid or tophus aspirates, because “the identification of crystals using polarising microscopy remains the gold standard for the diagnosis of gout owing to its 100% specificity.”
The experts acknowledge, however, that identifying crystals through microscopic analysis “may have some limitations in a primary care setting where most patients with gout are diagnosed and treated,” and recommend that the second step should involve clinical diagnosis of gout in patients with acute arthritis and “highly suggestive” features for gout, including monoarticular involvement of a foot or ankle joint, rapid onset of severe pain and swelling, male sex, and hyperuricemia.
Richette et al note that “there is no accepted definition of hyperuricemia,” but suggest use of the 6 mg/dL (360 µm) threshold “because the lifelong risk of gout increases above this level.” They caution, however, that “[t]he diagnosis of gout should not be made on the presence of hyperuricaemia alone.”
In situations where crystal identification is not possible and clinical diagnosis is uncertain, the taskforce says that the third step for diagnosis should involve imaging, particularly ultrasound, to search for evidence of monosodium urate crystal deposition and indicators of an alternative diagnosis.
The recommendations state that plain radiographs can be used to search for evidence of crystal deposition, but they have “limited value” for gout diagnosis, whereas ultrasound scanning “can be more helpful in establishing a diagnosis in patients with suspected gout flare or chronic gouty arthritis.”
The authors point out that “[a]s in the EULAR recommendations for the treatment of gout, the task force has emphasised […] the need to search for risk factors for hyperuricaemia once gout is diagnosed.” Such risk factors include “potentially modifiable” lifestyle factors such as obesity and consumption of excess alcohol, sugary drinks, meat, and shellfish.
They also underscore the importance of screening for the presence of comorbidities, especially obesity, chronic kidney disease, cardiovascular disease, and features of the metabolic syndrome, which they say “frequently coexist in patients with gout, but for which causality remains controversial.”
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