New gout definition: restricted to clinically evident disease

The label ‘gout’ should be reserved only for patients with clinically evident disease according to a new consensus statement that has established the first internationally accepted definition for the condition.

Led by Adelaide rheumatologist Dr David Bursill, the Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN)  brought together more than 80 gout experts from more than 20 countries to conduct a literature review, Delphi exercise and/or face-to-face consensus meeting to define and label eight gout disease states.

In the first stage of the project, consensus was reached on the labels and definitions for clinical elements including gout flare, chronic gouty arthritis and subcutaneous tophus, as well as imaging elements such as gouty bone erosion.

Speaking to the limbic, Dr Bursill of the the University of Adelaide said the objective of the second stage of the project was to reach agreement on the nomenclature of gout disease states – which, according to G-CAN is a ‘clinically meaningful cluster of the presence, or absence, of two or more disease elements’.

“There are literally dozens and dozens of different terms used throughout the scientific literature for these gout disease states elements. It’s confusing trying to compare results in scientific studies but also in communication with patients when we’re giving two different names to something.”

Noting that until now there had been no universally accepted definition of ‘gout’ itself, Dr Bursill says the G-CAN endorsed definition is probably the most important – and potentially controversial – finding to come out of the consensus statement.

“There has been an increasing use of advanced imaging like musculoskeletal ultrasound and dual energy CT scanning … that can pick up asymptomatic monosodium urate crystal deposition, and the question is: what does that actually mean?” he said.

“None of the international guidelines suggest we treat patients unless they’ve got clinically evident inflammatory consequences of crystal deposition. So for me, the consensus that gout is a clinical condition – that it’s not sufficient for someone to have presence of monosodium crystal deposition, they also have to have symptoms and signs of inflammation related to that including gout flare, chronic gouty arthritis or subcutaneous tophus – that’s an important one.”

Another key outcome was the rejection of non-specific labels of the clinical features of gout, such as ‘severe gout’, which are, despite their ambiguity, present in a number of international gout management guidelines, says Dr Bursill.

He argues that such ambiguity has played a part in the low rate of urate lowering therapy uptake in the community as well as poor monitoring and titration of the therapy among those who are on treatment.

“The thing about labels is they actually can convey a message to patients and practitioners. One of the problems we found was that the division between calling a gout flare ‘acute’ or calling tophi and erosions ‘chronic gout’ has led to a misunderstanding among patients that gout is only a chronic disease once it’s caused damage and that’s only when they need treatment. But we know that unless it’s treated the monosodium urate crystal deposition is always present.”

Other agreed labels include three pre-clinical states: asymptomatic hyperuricaemia, asymptomatic MSU crystal deposition, and asymptomatic hyperuricaemia with MSU crystal deposition.

And there is consensus on labels for three clinical states, which include gout, tophaceous gout, and erosive gout.

Two disease course states are also identified – the first gout flare and recurrent gout flares.

The Group recommends combining disease states when more than one is present, tophaceous and erosive gout, for instance.

In patients where there are other elements present, not recognised as disease states, these should be labelled as the recognised disease state with or without additional disease elements – tophaceous gout with chronic gouty arthritis for example.

The full consensus statement is published in the Annals of Rheumatic Diseases.

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