Developing classification criteria for CPPD
Research type
Research Study
Full title
Developing classification criteria for Calcium Pyrophosphate Deposition (CPPD) disease
IRAS ID
209198
Contact name
Abhishek Abhishek
Contact email
Sponsor organisation
University of Nottingham
Duration of Study in the UK
2 years, 9 months, 31 days
Research summary
The overall aim of this study is to develop and validate classification criteria for CPPD disease. It will allow us to better identify people with CPPD from people with other forms of arthritis. The specific objectives are to identify the clinical, imaging and laboratory features associated with CPPD disease; to develop a scoring system that can classify people with CPPD disease, distinguishing them from those without CPPD disease; and finally to validate the classification criteria system in an independent sample of patients with and without CPPD disease.
People with CPPD disease diagnosed by a physician and people with other types of arthritis that have a clinical presentation similar to CPPD disease will be invited to participate in this study. People participating in the study will undergo clinical review to collect information about symptoms of the rheumatic disease and comorbidities. With their permission, their medical case notes will be reviewed to collect information about comorbidities, previous investigations. Thus, each participant will undergo face-to-face visit or phone call of less than 30 minutes, and case note and results review.
Logistic regression will be used to examine the association between each clinical, laboratory and imaging feature and CPPD using data from 300 people with CPPD or other forms of arthritis that mimics CPPD. Odds Ratio will be calculated. These will inform the 1000 minds decision analysis at which each candidate item will be allocated a weight based on its ability to discriminate CPPD from other forms of arthritis. For each participant, criteria weights will be summed to provide a relative probability score for classification as CPPD. Expert opinion will then be used to decide the lowest cut-off score (threshold) that discriminates CPPD from other forms of arthritis. The performance of this score will be evaluated using data from the next 500 participants.
Summary of Results:
Calcium pyrophosphate deposition (CPPD) disease is very common and can cause painful arthritis. There was no way to reliably say who has this condition and who does not have this condition. We have developed a way to differentiate arthritis due to CPPD from other forms of arthritis. This is to promote additional research on this condition.
Supported by the American and European rheumatology societies called ACR and EULAR respectively, a group of experts followed well established methods to develop these criteria.
The group generated and refined a list of features that can differentiate this form of arthritis from other forms of arthritis. Data on these features was collected from participants. Doctors and scientists then held several meetings online to agree how important each item would be in separating CPPD disease from another condition. Using part of the data, the experts developed a scoring system that would help separate CPPD disease from other conditions. The accuracy of scoring system was checked using data from a separate group of patients.
Among patients with joint pain, swelling, or tenderness, whose symptoms are not fully explained by another disease, the presence of crowned dens syndrome or calcium pyrophosphate crystals in joint fluid were sufficient to classify a patient as having CPPD disease. In the absence of these findings, a score>56 points, can be used to classify as CPPD disease. These criteria identified 99 of every 100 patient with CPPD disease. Among the 100 people with CPPD disease identified by this way, 93 truly had the condition.
The 2023 ACR/EULAR CPPD disease classification criteria have excellent performance characteristics and will facilitate research in this field. They are not intended to be used for diagnosing patients with this condition and for research purposes alone.
REC name
South Central - Berkshire Research Ethics Committee
REC reference
20/SC/0243
Date of REC Opinion
1 Jun 2020
REC opinion
Favourable Opinion