A randomised, single blind study to evaluate the effects of action potential simulator therapy compared with placebo in patients with chronic back pain

This study investigated a relatively new device known as the Action Potential Simulator (APS) for pain relief in chronic low back pain with or without leg pain. The study had a single blind and parallel group design. A total of 24 patients were studied. Twelve patients received treatment with the active device and twelve with a placebo machine. Treatments were given for 8 minutes on 5 consecutive days. The results of visual analogue scores were compared pre- and post-treatment with both machines. The Oswestry Back Pain Questionnaire was completed before and at the end of the study and the results compared. There were significant effects on the VAS [visual analogue score] from visit 4 onwards. Newman Keuls tests showed significant differences both at visit 4 (p = 0.03) and visit 5 (p = 0.021) of sham versus active treatments. In terms of SD, the sham effect was about one-eight SD and active was one-quarter SD. This is a very small effect for both active and sham APS. Thus we conclude that APS therapy for chronic back pain in our group of patients was found to produce a small but clinically insignificant reduction in pain and took about 4 consecutive daily visits to show this effect.