Novel therapeutic agents: BOTOX (Botulinum Toxin Type A) treatment of patients with sub-acute low back pain: A randomized, double blind, placebo-controlled study

Abstract

BTX-A (Botulinum Toxin Type A, BOTOX®, Allergan) injections have become a common treatment for soft tissue back pain. However, rigorous placebo-controlled studies are uncommon in this indication. To assess BTX-A efficacy for sub-acute low back pain in a randomized, double blind, placebo-controlled, placebo run-in trial. At screening, placebo injections were made in 59 patients with low back pain (31m, 28f; average age:43; average pain VAS score: 7.31). Twenty-eight did not show a placebo response and were randomized into this study. At baseline, (screening +4 weeks), 15 patients received placebo and 13 received BTX-A. Injections were made at 5 bilateral paraspinal sites from lumbar 1 to para-lumbar 5. Per-site doses were 1.6 mL placebo, or 40U BTX-A totaling 400U in the treatment group. Examinations, (including two questionnaires: Oswestry Low Back Pain Disability, and Low Back Pain Impact), were made at screening, baseline, 4, 8, and 12 weeks. Patients kept a diary of concomitant medications and adverse events. At week 4 post-injection, average VAS scores had decreased –2.2 points in the BTX-A group and -0.3 points in the placebo group (p=0.03). By weeks 8 and 12 average scores had decreased -2.7 and -3.2 points with BTX-A, but only -1.0 and -1.1 points with placebo (p=0.036 and 0.01 respectively). Both questionnaires showed that although some patient perception indices improved with BTX-A, distinction between groups was inconclusive overall. BTX-A injections produce a significant and sustained decrease in low back pain VAS scores in patients pre-screened for responsiveness to placebo. While this result clearly demonstrates BTX-A efficacy, larger controlled trials are still needed.