| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Excellent internal consistency and stability, with Cronbach's alpha greater than 0.90. |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
Dysfunction index ICC > 0.9. Bother index (0.7 < ICC < 0.9 |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
SEM of 7.8 for the dysfunction index and 10.1 for the bother index |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Content validity for the dysfunction and bother indexes was supported with very little skew (less than 1.00), few ceiling effects (less than 5 percent), and no floor effects. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Tested |
| Brief Description |
The construct validity of SMFA appears to be adequate as the scores of both indexes correlate moderately to highly with disease specific and generic PROs evaluating perceived physical function. Moreover, correlations between SMFA scores and clinical measures such as range of motion, walking speed or strength are lower, as expected, as they represent different constructs. SMFA also discriminates successfully between subgroups based on clinical or demographical characteristics known to influence function |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
Convergent validity was supported with significant correlations between the SMFA dysfunction and bother indexes and the physicians' ratings of patient function (for example, activities of daily living, recreational and leisure activities, and emotional function [rho > or = 0.40]) and standard clinical measures (for example, grip strength and walking speed [r > or = 0.401). |