| MEASUREMENT PROPERTIES | |
| Limitations | English only |
| Observations |
To be scored, items should persist continuously for 6 months |
| 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) |
Interrater reliability was assessed in 10 actual patients with SLE, and the SDI detected differences among patients (P < 0.001) but not by physician (observer effect, P = 0.933). Concordance was demonstrated in the SDI among observers despite a wide spectrum of disease activity. |
| 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 | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
During the development of the index, 19 physicians scored the index on 42 case scenarios, and analysis showed that it could measure change in damage seen in patients with both active and inactive disease. Patients who had active disease had a higher increase in damage, and for those with stable disease, the damage index score did not change significantly. In a prospective study of 141 patients with SLE, components of the SDI were shown to be valid and associated with the immunosuppressive medication score. |
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Tested |
| Brief Description | |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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