Objectives: To compare the effects of a proprietary extract of willow bark (Assalix) and a selective inhibitor (rofecoxib) of the enzyme cyclo-oxygenase-2 (COX-2).
Methods: An open, randomized, post-marketing study was carried out in an out-patients clinic on two groups of patients aged 18 to 80 yr presenting over a 6-month period with acute exacerbations of low back pain. Using computer-generated random list, 114 patients were allocated to receive a daily dose of herbal extract containing 240 mg of salicin [PAID (phyto-anti-inflammatory drug) group] and 114 were allocated to receive 12.5 mg of the synthetic COX-2 inhibitor rofecoxib [NSAID (non-steroidal anti-inflammatory drug) group]. The doses were chosen according to existing recommendations. All patients were free to use whatever additional conventional treatments were thought necessary. The outcome measures were a modified Arhus index, its pain component and the Total Pain Index.
Results: Groups were well matched. After 4 weeks of treatment, the Arhus index had improved by about 20%, its pain component by about 30% and the Total Pain Index by about 35%. The number of pain-free patients (visual analogue scale score <2) was about 20 in each group. About 60% of the patients in each group responded well to the treatment (as judged by an improvement of >/=30% in the Total Pain Index relative to its baseline). The improvement was also reflected reasonably well in the physicians' and patients' judgements of the effectiveness of treatment, which were largely concordant. Few patients of either group resorted to the additional conventional treatment options. The incidence of adverse events was similar in the two groups. Treatment with rofecoxib was about 40% more expensive than that with Assalix.
Conclusion: There was no significant difference in effectiveness between the two treatments at the doses chosen. Treatment with Assalix was less expensive.