| 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) |
The reliability of certain measurements was evaluated by comparing the data from enrolment with those from follow-up visits at 6 months, and between 18 to 24 months. The tool used to establish this reliability was the ICC. The ICC for the parent's global assessment from enrolment to 6 months, as well as for all HRQoL measures, was below 0.7, which is typically considered the threshold for satisfactory reliability. ICC was also calculated for the 18-24 months period, which is generally more stable. During this later period, the ICCs for the parent's global assessment, HRQoML, and the Juvenile Arthritis Quality of Life Questionnaire (JAQQ) were indeed higher than in the earlier period. However, only the ICC for the JAQQ, calculated using the parent's change question, exceeded the critical threshold of 0.7, indicating good reliability. |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
The condition that the smallest detectable change (SDC) should be less than the minimal clinically important difference (MCID) for acceptable measurement error wasn't fulfilled by the parent global assessment or any of the health-related quality of life (HRQoL) measures. |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Face validity of the parent global as a measure of health may be surmised from multiple studies in which it is referred to as a measure of well-being. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Tested |
| Brief Description |
Construct validity was supported by moderate-to-high correlations with accepted HRQoL measures and correlations with non-HRQoL measures largely as predicted. |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
The parent's global assessment showed correlations with traditional disease activity measures, including the Physician's Global Assessment of Disease Activity (PGADA), the active joint count, and the Erythrocyte Sedimentation Rate (ESR), all of which were less than 0.5 at both enrolment and 6 months. In terms of discriminative construct validity, the parent's global assessment and all other HRQoL measures, with the exception of CHQ-Psychosocial, met the criteria for discriminative validity, as they showed significantly better scores during periods of inactive disease compared to active disease. Specifically, for the parent's global assessment, median values were 0.1 during inactive disease and 1.1 during active disease, indicating a significant difference. |