A total of 118 patients between 18 and 75 years of age with low back pain not attributable to identifiable causes were invited to participate. Criteria for eligibility included the following: a history of at least six months of low back pain, an acute increase of pain that affected both rest and movement, and the requirement of at least four weeks of symptomatic treatment. An appropriate sample size was selected to establish a confidence level of 95 percent.
The principal indicator of the analgesic power of devil's claw was established to be a reduced requirement for the analgesic Tramadol over the last three weeks of the study period. Daily phone contact with the patients allowed investigators to obtain a verbal 5-point rating scale of pain intensity (none, mild, moderate, severe, intractable). Secondarily, the Arhus low back pain index was modified and employed in an attempt to record the profiles of low back pain as appropriate to this study.
Patients in the treatment group received two 400-mg tablets of devil's claw extract three times a day (total 2,400 mg), equivalent to 6,000 mg crude root, calculated at a daily harpagoside level of 50 mg. Patients in the control group received a placebo. All participants completed a general health questionnaire, and were examined, and subjected to a venous blood draw that was analyzed for the conventional biochemical and hematological indices of organ system function.
A total of 109 patients completed the study -- 54 in the treatment group and 55 in the control group. Groups were matched on several measures, including the Arhus back pain index. A majority of the subjects had been suffering with back problems for about 15 years. Acute attacks lasting longer than three months had caused most of them to seek treatment. Approximately 90 percent had suffered physical impairment for more than 14 days in the previous six months, with pain in one or more other sites a common symptom. Greater pain with physical activity was a prevailing problem for about two-thirds of the group. Almost all patients had previously resorted to some treatment for the chronic condition, either regularly (59 percent) or irregularly (39 percent), and the average duration of treatment was about eight years. Non-opioid analgesics had been tried by about three-fifths of the patients with varying degrees of relief; other types of medications, including opioids, centrally actin g muscle relaxants, and anti-depressants, had also been used but to a lesser degree and with more limited relief overall.
Consumption of the supplementary pain-killer Tramadol did not significantly change, regardless of pain intensity; however, the number of pain-free patients increased from 0 to 9 in the treatment over the course of the study, compared to just one in the control group. An insignificant reduction in pain was confined almost entirely to a subgroup of patients whose pain did not radiate to one or both legs. There was a notable absence of identifiable clinical, hematological, or biochemical side effects.
While the primary outcome measure (reduction in Tramadol consumption) was not significantly changed, secondary measures (Arhus index) were impressive. The investigators suggest that, in light of the significant indications of safety and benefit, further trials with devil's claw investigating pain reduction would be worthwhile.
[Chrubasik, S., C. Zimpfer, U. Schutt, and R. Ziegler. 1996. Effectiveness of Harpagophytum procumbens in treatment of acute low back pain. Phytomedicine, Vol. 3(1), 1-10.]
Article copyright American Botanical Council.
~~~~~~~~
By Anne Tarleton