Gout: Preliminary Definitions for Ultrasound Findings Issued

Lara C. Pullen, PhD

May 21, 2015

New consensus-based ultrasound (US) definitions of elementary lesions in gout appear, at first impression, to be reliable. The definitions represent the initial step toward the development of core outcome measures that will allow future multicenter studies to compare outcomes from various gout clinical management protocols.

Marwin Gutierrez, MD, from the Universita Politecnica della Marche, Jesi, Italy, and colleagues describe the definitions in an article published online May 13 in Rheumatology. The definitions were created by an international panel of 32 US gout experts who have daily clinical and sonographic experience.

The authors note that US plays an important role in the diagnosis and management of gout. In addition, many rheumatologists incorporate US into their clinical assessment of gout, as well as their research. Despite this reliance on US, however, there is currently no standardized US approach for patients with gout, and no international consensus on the definitions of elementary lesions.

The rheumatologists performed three rounds of Delphi exercise to reach an agreement on the definition of four US gout elementary lesions: double contour, aggregates, tophus, and erosions. After the three rounds, the group had more than 80% agreement on the US definitions.

A web exercise was used to test inter- and intrareader reliability of the definitions. An electronic database was then constructed with 110 images, and the database was sent to participating rheumatologists.

The interreader κ values were 0.98 for double contour, 0.71 for tophus, 0.54 for aggregates, and 0.85 for erosion findings. The mean intrareader κ values were 0.93 for double contour, 0.78 for tophus, 0.65 for aggregates, and 0.75 for erosion findings. The authors considered these values acceptable.

Dr Gutierrez and colleagues say that the next step is to test the validity of the definitions when scanning patients with gout and undiagnosed gout in multicenter studies. Results from these investigations will likely translate into revisions of the preliminary definitions. The research will also determine whether the definitions are sensitive enough for the diagnosis of early gout.

Pascale Schwab, MD, a rheumatologist at Oregon Health & Science University School of Medicine in Portland, disagrees about the importance of US for the diagnosis of gout. Dr Schwab was not involved in the creation of the consensus guidelines, but discussed them with Medscape Medical News.

"The [US] criteria are likely to be helpful in patients with severe disease, and not for early diagnosis. The gold standard for a definitive gout diagnosis remains the demonstration of uric acid crystals in synovial fluid," she explained. She sees the definitions as potentially useful for certain aspects of gout research, but she does not think they will be particularly helpful for general clinicians, or even general rheumatologists.

Several authors have various financial relationships with Berlin-Chemie, Novartis, Esaote, General Electric, Siemens, Abbott Immunology, AbbVie, UCB Pharma, Esaote S.p.a, Bristol-Myers Squibb, Merck Sharp & Dohme, Pfizer, Janssen-Cilag, Roche, Schering Plough, Philips, Richter, and SonoSite. Dr Schwab has disclosed no relevant financial relationships.

Rheumatology. Published online May 13, 2015. Abstract

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