| MEASUREMENT PROPERTIES | |
| Limitations | English only |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Not Tested |
| Cronbach's (Describe) |
Not relevant. |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
For both formats of the PGI (“blind format” = without trigger list, and “closed format” = with the trigger list), test-retest reliability was assessed for patients reporting no change in both AS and general health: PGI scores had higher levels of reliability for the closed format (ICC = 0.88 (0.81-0.92)) than for the blind format (ICC = 0.82 (0.72-0.88)), although both formats are suitable for use in groups of patients. |
| C. Reliability interobserver or Measurement error | Not Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
|
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
The AS-specific trigger list was developed after semi-structured interviews were conducted to elicit a patient’s free responses about the influence of AS on their everyday life and the importance of areas affected by AS. Following a content analysis of the transcripts, verbatim statements reflecting important and common themes related to the HRQL of patients with AS were listed. Related themes were highlighted, grouped together, and organized by conceptual categories. The content analysis and category identification was discussed between members of the development team and assessed for repetition and ambiguity. Area selection for the trigger list was determined by conceptual categories, frequency of endorsement, and available space in the formatted instrument. |
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Not relevant. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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