| MEASUREMENT PROPERTIES | |
| Limitations | English only |
| 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 intraobserver reliability was 0.87 (95% CI 0.75 to 1.00). |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
The interobserver reliability using the ICC was 0.78 (95% CI 0.63 to 0.93). The interobserver reliability was better for patients with short compared with long disease duration: ICC was 0.87 (95% CI 0.74 to 0.99) for disease duration ≤3 years versus 0.67 (95% CI 0.33 to 1.0) for disease duration >3 years on the CDA. |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
It was constructed by a group of international experts in vasculitis from Europe and the USA |
| 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) |
For the total VDI and CDA scores there was a high positive correlation (ρ=0.90, p<0.001); a graphical representation of this is shown in figure 1. There was a high positive correlation between the organ system scores, except for ‘skin/mucous membrane’, where there was a moderate correlation (ρ=0.47, p<0.001). When the two skin-related items found in CDA but not VDI, ‘easy bruising’ (15.8% of patients) and ‘cutaneous scarring’ (9.0%) in the CDA, were removed from the analysis, the correlation was 0.70 (p<0.001). |