| MEASUREMENT PROPERTIES | |
| Limitations | |
| Observations | |
| 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) |
RA-FQ obtained 48–72 h apart (a time during which no change would be anticipated) in 93 patients with RA at 2 academic centers suggested high reliability [r = 0.94; ICC (2, 1) = 0.93, 95% CI 0.90–0.95]. |
| 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) |
Patients and physicians were involved in the development of the questionnaire. The foundational work was based on a reflective measurement model and grounded in qualitative studies with patients, thus ensuring a good match with patient-reported domains in the RA Flare Core Domain Set. Debriefing of the questionnaire throughout the process provided further evidence of match by people with RA. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Factor analysis was used to examine structural validity. The 5 items represented a single factor (81% of variance explained) with each item loading ≥ 0.84 (eigenvalue 4.064), supporting use of a summative score of the 5 domains (range 0 = no flare to 50 = extreme flare) to adequately represent RA flares. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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