There is only one independent study on the effectiveness of ActiPatch. Most, if not all of the other studies on ActiPatch were sponsored by the device company. Because of this, I would remain very sceptical of it until there are larger independent studies done.
There is a study on magnetic fields in the treatment of chronic pain. This study was done by two hospitals in conjunction with the creators of ActiPatch. The results of this study seem promising, but again I would be skeptical since the creators of ActiPatch were involved. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2670735/