| MEASUREMENT PROPERTIES | |
| Limitations | |
| 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) |
Measurement error was estimated by inter-rater reliability in 93 radiographs and by rescoring 50 radiographs to evaluate intra-rater reliability. Differences are reported as recommended using both intraclass correlation coefficients (ICCs). The SPARS intra-rater reliability was excellent for both readers (ICCs 0.945 and 0.976). |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
As compared to other methods, inter-rater reliability was highest for SPARS (ICC = 0.884, 95% CIs 0.852 to 0.898), followed by PARS (ICC = 0.869, 95% CIs 0.842 to 0.889), and mSvdHS (ICC = 0.819, 95% CIs 0.802 to 0.838) |
| 2. VALIDITY | |
| A. Content validity: face validity | Not Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
|
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Not Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Convergent construct validity was investigated by the correlation (using Pearson’s rank correlation test) with other scores. SPARS strongly correlated with mSvdHS (r = 0.926, p < 0.0001) and PARS (r = 0.904, p < 0.0001). |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
Since there is no true external gold standard, a new method can be compared to the traditional scoring systems for PsA, such as mSvdHS and PARS. In this regard, SPARS correlated strongly with mSvdHS and PARS as explained above. |