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The Overall Disability Sum Score (ODSS) was the first scale designed to assess the limitations of patients with immune-mediated peripheral neuropathies. 1 It was derived from the Guy's Neurological Disability Scale, 2 a scale that was developed for assessing disability in patients with multiple sclerosis. The ODSS focuses on upper and lower limb functions, and consists of a checklist for interviewing patients. It is scored from 0 to 5 on the upper limb section and from 0 to 7 on the lower limb section. A score of 0 indicates no limitations (the ceiling of the scale) and a score of 5 or 7 indicates no purposeful movement.
The ODSS showed intrarater and inter-rater reliability, responsiveness and construct validity in people with Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and paraprotein-associated demyelinating neuropathy. 1, 3 It has been successfully used to assess disability in clinical trials and investigations. 3, 4
The published description of the ODSS, however, does not interrogate patients on difficulties with climbing stairs or running. To reduce a possible ceiling effect, we have modified the ODSS slightly to include climbing stairs and running. Specifically, the ODSS item "Does the patient have difficulty walking?" has been supplemented with "Does the patient have difficulty running or climbing stairs?" on the new measure, the Overall Neuropathy Limitations Scale (ONLS; appendix). Therefore, to score 0 (indicating no limitations) on the lower limb section of the ONLS, the patient must now have no difficulty running or climbing stairs, in addition to walking. The remaining scoring criteria are not different from those in the ODSS.
We have refined the instructions (available online at http://www.jnnp.bmjjournals.com/supplemental ) for administering the scale. We also investigated whether the ONLS could be used as an observed measure by clinicians watching patients perform the tasks outlined on the ONLS. The changes to the scale, although minor, and its use in a wider range of peripheral neuropathies, required a renewed clinimetric evaluation, which we present here.
METHODS
Patients
With permission from our local ethics committee, we filmed 35 patients performing the tasks listed on the ONLS in addition to completing the ONLS interview. The film was scored independently by four raters: two neurologists and two physiotherapists. We then audited the use of the ONLS interview...