| MEASUREMENT PROPERTIES | |
| Limitations | |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Not Tested |
| Cronbach's (Describe) | |
| B. Reliability intraobserver or test-retest | Not Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
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| 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 | Not Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
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| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Construct validity was tested by computing the standardized mean difference (SMD) against the decision to change treatment (defined as new prescription or increasing dose/switching urate-lowering treatment not related to adverse reactions, and/or prescription of symptomatic drugs such as colchicine/nonsteroidal anti-inflammatory drugs/intra-articular or systemic glucocorticoids, or the occurrence of a gout flare within the following 6 months), categorized physician VAS of response to treatment, and the patient’s perception of being in remission as coded in the GIS. The SMD for the GAS3 step-c showed good discriminatory ability for each external criterion (SMD 1.03-1.22; P < 0.001). |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
Criterion validity was assessed using Spearman’s correlation coefficient of the GAS score against the HAQ score and SF-36 physical component summary (SF-36 PCS) and mental component summary (SF-36 MCS). There was strong correlation at 12 months between the GAS3 step-c and the HAQ (r = 0.50; ρ < 0.001) and SF-36 PCS (r = −0.53; ρ < 0.001) and a moderate correlation with the SF-36 MCS (r = −0.30; ρ < 0.001). |