Herbal medicine and physical impairment.
Intervention studies in chronic lower back pain have, since the introduction of the Arhus low back pain index in 1994, used physical impairment as a subscale to measure outcome success. Physical impairment is defined as objective structural or physiological limitation that may partly account for loss of function, although it may also include a psychological component. Recently the usefulness of recording this component in chronic lower back pain has been questioned, as physical impairment scores were less responsive to treatment interventions than scores of the other two subscales: disability and pain.
German researchers Chrubasik et al recently undertook a re-analysis of all their studies examining the impact of Harpagophytum procumbens and a proprietary extract of Salix on chronic lower back pain. Each of their studies used the Arhus index as an assessment tool (which includes a physical impairment component). For comparison they extracted data from studies of capsaicin as a topical preparation for the same condition. Their aim was to determine the generality of claims that physical impairment as a scale is relatively unresponsive to interventions intended for the symptoms of chronic lower back pain.
The re-analysis included 7 studies on the effects of Harpagophytum procumbens, 3 on a Salix extract and one of capsaicin. Three were randomised double blind placebo controlled studies, one was an open double blind placebo controlled study, two were randomised double blind comparisons with a conventional NSAID, one was an open controlled comparison with NSAIDs, and three were open uncontrolled studies.
Results showed that the disability scores on the Arhus index changed with the pain component, but that the activity of the physical impairment scale was more complex. Barring one study which showed significant change in all markers, the physical impairment index changed very little from baseline, or to a much lesser degree than assessments of pain and disability. This seems to confirm the comparative insensitivity of the measure and exclude the notion that such unresponsiveness is related purely to a particular medication. The one study displaying significant change in the measure was undertaken in Israel, while the rest were completed in Germany, albeit under the same conditions.
The researchers note the psychological component of physical impairment, and suggest that attempts to quantitatively measure this component may be affected by patient's motivation, which may have differed in the different cultural groups. They also suggest that perhaps the trials which showed no improvement had not been specifically targeted at the structural, physical or psychological changes that take place in sufferers of lower back pain.
While a physical impairment measure has its place in some intervention strategies, the researchers' results cast doubt on how useful it is as a measure of the potential effects of herbal and other medicines on chronic lower back pain.
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|Title Annotation:||Reviews of articles on medicinal herbs|
|Publication:||Australian Journal of Medical Herbalism|
|Date:||Sep 22, 2008|
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