| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Not Tested |
| Cronbach's (Describe) | |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
The outcome measures that composse the MDA have been assessed in PsA and have been shown to be reliable. In a study assessing agreement among dermatologists and rheumatologists, there was substantial agreement (0.6 >/= ICC < 0.80) on the TJC, PASI, and NN, moderate agreement (0.4 >/= ICC < 0.60) on the PGA-Ps, LS-PGA, NPF-PS, and BSA, and fair agreement (0.2 >/= ICC < 0.40) on the SJC, dactylitis, and PGA-PsA. |
| C. Reliability interobserver or Measurement error | Not Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
|
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
The design of the criteria is based partially on the development of similar measures in RA by the OMERACT group. The development of the PsA criteria was discussed and debated within the Executive Committee of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA), who are an international panel of experts in psoriatic disease. This expert input into the criteria’s developmental phase provided face validity for the criteria. |
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description | |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
Coates and Helliwell reported moderate agreement (κ=0.73–0.75) with three alternative definitions of treatment responses: PASDAS, CPDAI-4 and CPDAI-3. |