The 2023 ACR/EULAR Classification Criteria for Calcium Pyrophosphate Deposition Disease

Abstract

ObjectiveCalcium pyrophosphate deposition (CPPD) disease is prevalent and has diverse presentations, but there are no validated classification criteria for this symptomatic arthritis. The American College of Rheumatology (ACR) and EULAR have developed the first‐ever validated classification criteria for symptomatic CPPD disease.MethodsSupported by the ACR and EULAR, a multinational group of investigators followed established methodology to develop these disease classification criteria. The group generated lists of candidate items and refined their definitions, collected de‐identified patient profiles, evaluated strengths of associations between candidate items and CPPD disease, developed a classification criteria framework, and used multi‐criterion decision analysis to define criteria weights and a classification threshold score. The criteria were validated in an independent cohort.ResultsAmong patients with joint pain, swelling, or tenderness (entry criterion) whose symptoms are not fully explained by an alternative disease (exclusion criterion), the presence of crowned dens syndrome or calcium pyrophosphate crystals in synovial fluid are sufficient to classify a patient as having CPPD disease. In the absence of these findings, a score >56 points using weighted criteria, comprising clinical features, associated metabolic disorders, and results of laboratory and imaging investigations, can be used to classify as CPPD disease. These criteria had a sensitivity of 92.2% and specificity of 87.9% in the derivation cohort (190 CPPD cases, 148 mimickers), whereas sensitivity was 99.2% and specificity was 92.5% in the validation cohort (251 CPPD cases, 162 mimickers).ConclusionThe 2023 ACR/EULAR CPPD disease classification criteria have excellent performance characteristics and will facilitate research in this field.

2023 EULAR recommendations on imaging in diagnosis and management of crystal-induced arthropathies in clinical practice

“…While evidence of MSU deposition in synovial fluid or tissue analysis remains the diagnostic hallmark, it has been recognised that this may not always be possible, due to unsuccessful arthrocentesis or lack of facilities/expertise to analyse joint fluid. 34 Other expert groups have acknowledged this, as evidenced also by recent classification criteria which consider imaging evidence of crystal deposition among the criteria in patients with imaging signs typical for gout or CPPD disease but lacking confirmation of relevant crystals of synovial fluid analysis in an appropriate clinical scenario suggestive of the disease (8)(9)(10). The decision on whether to perform arthrocentesis should be evaluated in the clinical context; however, as a general rule, this should be always attempted, whenever feasible, especially for ruling out other causes of acute arthritis, such as septic arthritis, regardless of whether there is previous evidence for gout (for instance, positive DECT and hyperuricaemia).…”

Describing calcium pyrophosphate deposition: undoing the tower of Babel!

“…However, should be kept in mind that a significant limitation in describing CPPD by radiography lies in its two-dimensional nature, where the superimposition of different structures, especially in case of advance osteoarthritis, can affect the recognition of CPP deposits [35]. Indeed, recent studies have confirmed that the sensitivity of radiography for CPPD identification is far from being optimal, but thanks to its high specificity, detecting CPPD on radiography is considered at the same level as ultrasound and CT in the recently published classification criteria for CPPD disease [8 ▪▪ ,9 ▪▪ ]. The development of a radiographic scoring system for CPPD extent in the near future, could contribute further to enhancing the role of radiography in characterization of CPPD.…”

“…Furthermore, the recently developed 2023 ACR/EULAR classification criteria for CPPD disease have contributed to a more precise definition and characterization of the symptomatic form of the disorder [8 ▪▪ ,9 ▪▪ ]. This is a cornerstone for research of CPPD enabling enrolment of patients with similar characteristics in CPPD studies, thus by-passing one of the major problems in the literature: heterogeneity of the cohorts making not comparable the results of the studies.…”

“…Given the complex nature of the disease and the challenges in the exact nosologic description that emerged since the origin (Fig. 1), the scientific community is working towards standardizing various aspects of CPPD, beginning with the recently developed ACR/EULAR classification criteria [8 ▪▪ ,9 ▪▪ ], the homogenization of imaging definitions [10,11,12 ▪ ] and the forthcoming results of the project by Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) for developing a consensus nomenclature for CPPD.…”

Calcium pyrophosphate deposition disease: historical overview and potential gaps

“…2023. Publication of the ACR/EULAR CPPD disease classification criteria, which showed very good diagnostic performance and provided guidance for future research ( 54 ).…”