| MEASUREMENT PROPERTIES | |
| Limitations | English only |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Cronbach’s alpha 0.60-0.94 (range for the different items of the scale). These results were replicated in the study by Khanna (2011), with similar results.
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| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
The 2 week test-retest showed ICC ranging from 0.77 to 0.89 for the different items of the scale.
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| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
SEM ranged 5.9-10.9. |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
The 14 items assessing gout impact on HRQOL were deemed important for assessing gout effect on daily life by a group of patients, and also extra items were suggested and added to the final 27 items questionnaire. |
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
The construct validity of all 5 scales of the GIS is unclear. The overall concept of “impact of disease” is ambiguous and not well-defined. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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