Charlotte Jauffret (1), Silvia Sirotti (2), Edoardo Cipolletta (3), Daniele Cirillo (4), Luca Ingrao (4), Alessandro Lucia (4), Enrico Cumbo (4), Antonella Adinolfi (6), Emilio Filippucci (3), Tristan Pascart (1), Sara K. Tedeschi (7), Robert Terkeltaub (8), Nicola Dalbeth (9), Georgios Filippou (2)
Affiliation(s):
1. Department of Rheumatology, Saint-Philibert Hospital, Lille Catholic University, Lille, France
2.Department of Rheumatology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
3. Rheumatology Unit, Department of Clinical and Molecular Sciences, Polytechnic University of Marche, Ancona, Italy
4. Department of Clinical Sciences and Community Health, Università degli Studi di Milano, Milan, Italy
5. Department of Rheumatology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
6. Rheumatology Unit, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy
7. Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
8. Veterans Affairs San Diego Healthcare System, University of California, San Diego, USA
9. Bone and Joint Research Group, Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
Background: Despite prior attempts at standardizing terminology of calcium pyrophosphate deposition (CPPD) disease (e.g. the 2011 EULAR recommendations), many different terms are still used interchangeably to describe the disease, its elements, and its states 1,2. This confusing nomenclature, associated with inaccurate and vague ICD10 coding, slows advances in research and in patient care compared to other inflammatory rheumatic diseases. The Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) has developed a CPPD Nomenclature Project which aims to achieve international consensus about the nomenclature of CPPD.
Objectives: In this first step of the project, the aim was to identify the disease elements and the clinical states of CPPD and their corresponding labels reported in the scientific literature.
Methods: A systematic literature search was undertaken in the PubMed database starting from first January 2000 to 31 August 2022. The search was restricted to studies on humans and in the English language. Eight reviewers independently extracted terms related to disease definition, aetiology, pathogenesis, clinical presentation, imaging features and clinical states of CPPD. An a priori list of disease elements and clinical states was generated by the authors and further elements were added during data collection as appropriate. Labels for each identified disease element and clinical state were manually extracted, and analysed to determine their frequency, before and after the 2011 EULAR recommendations on CPPD terminology.
Results: A total of 2,376 articles were identified using the search criteria. In the final analysis, 886 articles were included, of which 569 were published after 2011, and 394 (44.5%) were case reports. There was great inconsistency in the terminology used. Before and after 2011, the most common labels used to identify the disease were “pseudogout” (respectively 45.7% and 38.8%) and “calcium pyrophosphate dihydrate crystal deposition disease” (respectively 43.5% and 51.5%). The most common acronym was “CPPD” (35.2%), mostly with the meaning “calcium pyrophosphate dihydrate crystal deposition” (23.6%) only after 2011. The asymptomatic clinical form was rarely mentioned, mainly as “asymptomatic chondrocalcinosis” (3.0%). Before and after 2011, the 2 most commonly used labels describing “an episode of acute CPPD arthritis” were “pseudogout” (respectively 19.9% and 16.9%), and “acute calcium pyrophosphate crystal arthritis” (respectively 0.6% and 10.5%). Before and after 2011, “chronic calcium pyrophosphate crystal arthritis” (respectively 0.3% and 5.4%) and “pseudo-rheumatoid arthritis” (respectively 3.8% and 2.6%) were the most commonly used labels to describe “persistent inflammatory arthritis due to CPPD”. The most used labels used to identify “osteoarthritis with evidence of CPPD” after 2011 was “chronic calcium pyrophosphate crystal arthritis related-osteoarthritis” (7.0%). The use of “pseudo-form” labels mostly occurred before the 2011 EULAR recommendations. Our results show the discrete impact of those recommendations after 2011.
Conclusions: Those results demonstrate the heterogeneity and lack of precision in the labels used to describe CPPD disease, even after the 2011 EULAR recommendations. The next steps of the project will be to achieve agreement about CPPD disease scientific nomenclature through a Delphi exercise and consensus meeting, and to develop an easily understandable common lay language definitions to facilitate communication with patients.
References:
1. Zhang W, Doherty M, Bardin T, et al. European League Against Rheumatism recommendations for calcium pyrophosphate deposition. Part I: terminology and diagnosis. Ann Rheum Dis 2011; 70: 563–570.
2. Tedeschi SK. Issues in CPPD Nomenclature and Classification. Curr Rheumatol Rep 2019; 21: 49.