Development and internal–external cross-validation of a patient-reported definition for acute calcium pyrophosphate crystal arthritis
Authors' conclusion
We developed and initially validated easy-to-use patient-reported definitions for acute CPP crystal arthritis for use in clinical trials and observational research in CPPD.
Study context
- Population
- Consecutive patients with crystal-proven CPP deposition (CPPD) disease from seven centres across four countries (mean age 73.2 years, 65.9% female)96/246 (39.0%) with acute CPP crystal arthritis
- Participants
- 246 patients
- Exposure
- Patient-reported definitions vs expert opinion of an independent rheumatologist (reference standard)
- Outcome
- Ascertainment of acute CPP crystal arthritis vs expert opinion (discrimination, calibration, sensitivity, specificity)
Methodological detailsmulticentre (seven centres, four countries), consecutive patients, multivariable logistic regression with backward selection, classification and regression tree (CART), internal–external cross-validation
- Multicentre (seven centres, four countries)
- Consecutive patients
- Multivariable logistic regression with backward selection
- Classification and regression tree (CART)
- Internal–external cross-validation
Main finding
As reported in the abstract
Ascertainment of acute CPP crystal arthritis
| Group | Optimism-adjusted c-index | Sensitivity | Specificity | Optimism-adjusted calibration slope | Optimism-adjusted calibration-in-the-large |
|---|---|---|---|---|---|
| Logistic model | 0.92 (95% CI: 0.89, 0.95) | 0.83 (95% CI: 0.74, 0.90) | 0.86 (95% CI: 0.79, 0.91) | 0.95 (95% CI: 0.71, 1.19) | 0.005 (95% CI: −0.37, 0.37) |
| CART | — not stated in the abstract | 0.83 (95% CI: 0.72, 0.91) | 0.83 (95% CI: 0.74, 0.90) | — not stated in the abstract | — not stated in the abstract |
Optimism-adjusted c-index
Logistic model0.92 (95% CI: 0.89, 0.95)
CART— not stated in the abstract
Sensitivity
Logistic model0.83 (95% CI: 0.74, 0.90)
CART0.83 (95% CI: 0.72, 0.91)
Specificity
Logistic model0.86 (95% CI: 0.79, 0.91)
CART0.83 (95% CI: 0.74, 0.90)
Optimism-adjusted calibration slope
Logistic model0.95 (95% CI: 0.71, 1.19)
CART— not stated in the abstract
Optimism-adjusted calibration-in-the-large
Logistic model0.005 (95% CI: −0.37, 0.37)
CART— not stated in the abstract
— not stated in the abstract
Observational data: associations, not effects.
Original publication
Development and internal–external cross-validation of a patient-reported definition for acute calcium pyrophosphate crystal arthritis. Rheumatology (Oxford). Published 14 December 2024. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →