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Agreement Strength

In summary, previous results suggest that manual muscle tests, graded by the RCM scale, have a relatively low sensitivity to objective measurement of muscle strength and that even pronounced muscle weakness may remain undetected. Paradoxically, however, the researchers viewed the 6 categories of the initial MRC scale as an overly un discriminatory ability to grasp the finer details of manual muscle tests, which could be interpreted to mean that the problem does not exist with clinical muscle tests themselves, but in the categorization provided by the MRC scale. This seems particularly marked in the grey area between the „4“ and „5“ classes. In addition, with respect to spinal pain and radiculopathy, clinical experience is that muscle weakness in the `0` to `3` classes is rare, and we have the impression that the most commonly used modification of the original CKRM scale is the addition of `4` as an intermediate step between `4` and `5`. Overall, we would therefore say that the five cases were ambivalently formulated to promote an „average“ response in the grey area between „4“ and „5“. Assuming this premise, the results of the modified MRC group should have been more consistent with the standard MRC group. Instead, the „4“ option apparently added only an additional response option to be ambivalent, which led to larger and no less numerous disparities in the modified MRC group. In terms of research, the categories of a clinical muscle strength scale must correspond to the discriminatory capacity of muscle tests. If clinically relevant details such as those described above are lost during translation, it is tempting to add other categories. However, it makes little sense to construct weighing instruments with clinically relevant categories if review procedures are not able to distinguish between them. The discriminatory capacity of clinical muscle power tests must therefore be determined before appropriate scales can be established to reflect these results.

The distribution of responses in Case A was essentially similar between the groups, with „4“ simply replacing „4“ in the modified MRC group. However, in Case B, a proportionally larger number of ratchets in the modified MRC group opted for „4“ when they had the „4“ option. As described in the section above, some councillors chose „3“ in Case C – not because of a lack of knowledge of the scale, but because they felt a weakness against gravity and a progressive weakness that warranted a „3“ grade. In any event, the vast majority of advisors in the standard MRC group chose „4“ for Case C, while the amended MRC group was more evenly divided between „4,“ „4“ and „5,“ with only 3 councillors choosing „3.“ Case D differed from other cases in that the answer in the case description „You find a weakness [..] Grade 4 [..] was given, and in addition, the character of the vulnerability was indicated as „primarily because of pain.“