| MEASUREMENT PROPERTIES | |
| Limitations | <5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
The OA-Quest subscales showed high internal consistency. Values of Cronbach's alpha ranged from 0.85 (Physical de-conditioning) to 0.96 (Sleep disturbances). |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
Temporal stability was ICC= 0.75 |
| 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 | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Patients and health professionals participated in the item selection of the OA quest. Cognitive interviews supported face and content validity of the questionnaire. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
A 7-factor solution produced factors that corresponded to the Physical distress, Physical limitations, Psychosocial distress, Sleep disturbances, Physical de-conditioning, Lost productivity, and Financial hardship dimensions of the PBO framework. The Fatigue items did not emerge as a separate dimension and were strongly associated with the Physical distress and Lost productivity factors. The solution explained 74% of variance in the data. Each factor had at least four strong (>0.5) loadings and there were only 20 crossloading items. The 7-factor model had a very good fit, providing strong support for the convergent validity of the OA-Quest. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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