| 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 levels of agreement attained, based upon +/- one grade were high, range from 96% to 98% for test-retest reliability. |
| C. Reliability interobserver or Measurement error | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
A Rasch analysis performed to investigate physicians’ ability to discriminate among the MRC-5 scale categories demonstrated a poor inter-individual reproducibility since physicians have limited discriminating abilities in this 5-grade system The levels of agreement attained, based upon +/- one grade were high, from 82% to 97% agreement for interexaminer reliability. |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
The MRC scale was developed by British physicians during World War II to grade strength after injuries. It was expanded and adapted to neuromuscular research in the 1970s. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Not Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
There have been a number of papers that have specifically described the validity of MRC-MMT in relationship to patients with low back pain. The correlation between "inhibited" or "weak" MRC findings and low back pain has been well established in the research literature. |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
Marino et al (1982) and Wadsworth et al (1987) showed significant reliability between handheld dynamometers and MRC-MMT. Scores measured with the dynamometers were consistent with the examiner's perception of muscle weakness (P less than 0.001) in both studies. |