The Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) has issued a consensus statement presenting recommended labels and definitions for the disease states of gout. The publication is the culmination of an international project aimed at addressing the lack of standardization in the terminology used to describe the disease.

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The first phase of the G-CAN gout nomenclature project resulted in the publication of a consensus statement that provided labels and definitions for the disease elements of gout, including ‘serum urate’, ‘hyperuricaemia’, as well as clinical elements, such as ‘gout flare’, ‘chronic gouty arthritis’ and ‘subcutaneous tophus’, and imaging elements such as ‘gouty bone erosion’. Building on these results, the second, current stage of the project aimed to reach consensus on the nomenclature of the disease states of gout, defined as “a clinically meaningful cluster of the presence, or absence, of two or more disease elements”.

“The nomenclature provides an important framework for how disease elements and disease states of gout should be represented in the literature,” says corresponding author David Bursill. “We hope it will promote consistency in the language used to describe gout.”

The work to establish labels and definitions of gout disease states involved a content analysis of the literature to identify the language currently used, followed by a Delphi exercise and a face-to-face consensus meeting aimed at reaching agreement on nomenclature. “This project was an international collaboration and was able to bring together the opinions of a large number of rheumatologists and non-clinician researchers with a particular interest in gout,” reports Bursill. “The use of online surveys to conduct the Delphi component was successful in collating and processing the input from a large number of contributors, and the face-to-face meeting allowed us to refine the final nomenclature, which is comprehensive and succinct.”

The analysis of gout-related and hyperuricaemia-related literature identified 13 disease states, which were then categorised as preclinical states, clinical states or states describing the disease course of gout. “We found that preclinical states were poorly represented in the literature despite this being an area of increasing interest, particularly with improved detection of asymptomatic crystal deposition through advanced imaging,” Bursill comments. “Terms describing states of high disease activity were common but non-specific, and those that described low disease activity were rare. Terms describing the disease course of gout were also non-specific, with labels such as ‘early gout’ or ‘longstanding gout’ commonly used.”

Following the Delphi exercise (involving 76 respondents) and the face-to-face meeting (35 attendees), eight of the disease states identified in the literature analysis were deemed meaningful — that is, having important implications for disease management or prognosis, or both. Consensus agreement was then reached on the labels and definitions for these eight disease states. The G-CAN endorsed labels include ‘asymptomatic hyperuricaemia’, ‘asymptomatic monosodium urate crystal deposition’, ‘asymptomatic hyperuricaemia with monosodium urate crystal deposition’, ‘gout’, ‘tophaceous gout’, ‘erosive gout’, ‘first gout flare’ and ‘recurrent gout flares’.

Bursill highlights that the terms were chosen not only for their accuracy, but also to convey important concepts in gout aetiology, pathogenesis and clinical presentation. “The most important result was the consensus definition for the term ‘gout’. Rather than just the presence of monosodium urate crystals, ‘gout’ should only be used when there are current or prior clinical symptoms or signs of monosodium urate crystal deposition,” he explains.

the terms were chosen not only for their accuracy, but also to convey important concepts in gout aetiology, pathogenesis and clinical presentation

G-CAN intends for the consensus labels to be used in the scientific literature and in clinical settings. “This nomenclature needs to be widely distributed to those involved in the clinical care of patients with gout or to those researching this disease,” says Bursill. “We hope that a consistent, accurate and informative nomenclature will facilitate communication in all aspects related to gout.”