LA JOLLA, CALIF. – Twelve years ago, an international task force of the European Alliance of Associations for Rheumatology (EULAR) released recommendations regarding nomenclature in calcium pyrophosphate deposition disease (CPPD), aiming to standardize the way the condition is described. “Pseudogout” was out, and “acute CPP crystal arthritis” was in, and a confusing array of multi-named phenotypes gained specific labels.
Since 2011, the nomenclature guidelines have been cited hundreds of times, but a new report finds that the medical literature mostly hasn’t followed the recommendations. The findings were released at the annual research symposium of the Gout, Hyperuricemia, and Crystal Associated Disease Network (G-CAN), which is taking another stab at overhauling CPPD nomenclature.
“The objective is to uniform and standardize the labels of the disease, the disease elements, and the clinical states,” rheumatologist Charlotte Jauffret, MD, of the Catholic University of Lille (France), said in a presentation. CPPD is a widely underdiagnosed disease that’s worth the same efforts to standardize nomenclature as occurred in gout, she said.
As Dr. Jauffret explained, CPPD has a diversity of phenotypes in asymptomatic, acute, and chronic forms that pose challenges to diagnosis. “The same terms are used to depict different concepts, and some disease elements are depicted through different names,” she said.
Among other suggestions, the 2011 EULAR recommendations suggested that rheumatologists use the terms chronic CPP crystal inflammatory arthritis instead of “pseudo-rheumatoid arthritis,” osteoarthritis with CPPD, instead of “pseudo-osteoarthritis,” and severe joint degeneration instead of “pseudo-neuropathic joint disease.”
Later reports noted that terms such as CPPD and chondrocalcinosis are still wrongly used interchangeably and called for an international consensus on nomenclature, Dr. Jauffret said.
For the new report, Dr. Jauffret and colleagues examined 985 articles from 2000-2022. The guidelines were often not followed even after the release of the recommendations.
For example, 49% of relevant papers used the label “pseudogout” before 2011, and 43% did afterward. A total of 34% of relevant papers described CPPD as chondrocalcinosis prior to 2011, and 22% did afterward.
G-CAN’s next steps are to reach consensus on terminology through online and in-person meetings in 2024, Dr. Jauffret said.
Use of correct gout nomenclature labels improved
In a related presentation, rheumatologist Ellen Prendergast, MBChB, of Dunedin Hospital in New Zealand, reported the results of a newly published review of gout studies before and after G-CAN released consensus recommendations for gout nomenclature in 2019. “There has been improvement in the agreed labels in some areas, but there remains quite significant variability,” she said.
The review examined American College of Rheumatology and EULAR annual meeting abstracts: 596 from 2016-2017 and 392 from 2020-2021. Dr. Prendergast said researchers focused on abstracts instead of published studies in order to gain the most up-to-date understanding of nomenclature.
“Use of the agreed labels ‘urate’ and ‘gout flare’ increased between the two periods. There were 219 of 383 (57.2%) abstracts with the agreed label ‘urate’ in 2016-2017, compared with 164 of 232 (70.7%) in 2020-2021 (P = .001),” the researchers reported. “There were 60 of 175 (34.3%) abstracts with the agreed label ‘gout flare’ in 2016-2017, compared with 57 of 109 (52.3%) in 2020-2021 (P = .003).”
And the use of the term “chronic gout,” which the guidelines recommend against, fell from 29 of 596 (4.9%) abstracts in 2016-2017 to 8 of 392 (2.0%) abstracts in 2020-2021 (P = .02).
One author of the gout nomenclature study reports various consulting fees, speaker fees, or grants outside the submitted work. The other authors of the two studies report no disclosures.