| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations |
No translation needed. |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Reliability of the 8 items included in the questionnaire was high; this was shown using Cronbach’s alpha, which gave a value of 0.72. For the 4 items in the PDAS1 and PDAS2, Cronbach’s alpha was 0.5 and 0.4, respectively |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
Test–retest reliability was assessed for each item within 24 hours of initial assessment and was graded as excellent, with interclass correlation coefficients ranging from 0.76–0.88 for both the PDAS1 and PDAS2 |
| C. Reliability interobserver or Measurement error | Not Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
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| 2. VALIDITY | |
| A. Content validity: face validity | Not Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
The PDAS1 includes 3 of the 7, and the PDAS2 includes 2 of the 7 ACR core set measures used to assess outcomes in RA. While self-assessed joint counts are not included in the ACR core set of measures, self-assessed joint counts have been shown to variably correlate with joint counts performed by physicians (R = 0.41–0.78), but are not equivalent, with patients rating joint tenderness higher than physicians. |
| 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) |
The PDAS2 is less sensitive than both the PDAS1 and DAS28 for detecting low disease activity. Agreement of EULAR good and moderate response withPDAS1 and PDAS2 wask= 0.46 (95% CI: 0.27, 0.64) and 0.38 (95% CI: 0.20, 0.56), respectively. |