| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
α = 0.936 |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
ICC = 0.93 (0.90–0.95) |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
SDD = 2.13 95% CI of 95% limits of agreement = -2.48 to 2.47 |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Items were generated by an expert group of physiotherapists, researchers, rheumatologists, and patients (however the role of patients is not made explicit). |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Good evidence of validity through comparison with instruments that measure similar or related constructs, and with measures of mobility. The BASFI is highly correlated with the Dougados Functional Index (Spearman’s correlation coefficient = 0.89). Correlations are less strong with patient-reported disease activity (r=0.33) or physician-reported disease activity (r=0.33) |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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