| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations |
Using a sample of 392 patients with AS, the BAS-G was assessed for its variability, temporal reliability and construct validity |
| 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 test-retest reliability was excellent (1 week r = 0.84, 6 months r = 0.93). ICC BAS-G last 6 months = 0.85 (0.72–0.93) ICC BAS-G last week = 0.91 (0.82–0.96) |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
SDD BAS-G last 6 months = 3.07 95% CI of 95% limits of agreement BAS-G last 6 months = -3.46 to 3.66 SDD BAS-G last week = 3.51 95% CI of 95% limits of agreement BAS-G last week= -3.46 to 3.66 |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
In a pilot study, the most appropriate wording for the global measure was ascertained. The final question (in two versions) asks patients to indicate the effect of AS on their well-being over the last week/6 months, using a 10 cm horizontal visual analogue scale. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Tested |
| Brief Description |
The best fitting regression equation (adjusted R2 = 0.S5) included gender, current age, BASDAI and BASFI, suggesting that these are the main identified components of the BAS-G score. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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