we did not quantify subjects' ability to distinguish active from sham or expectations of pain relief.
Subjects were informed during recruitment and at consent that this was an exploratory trial and would not lead to a long-term replacement for treatment.
Nonetheless, 3 points of evidence suggest that the sham procedure could not be reliably identified from the active procedure;
(1) The sham successfully elicited a temporary placebo response (Fig.
3);
(2) The time dynamics of the pain reduction effects were comparable across the active and sham conditions regardless of randomization (Supplemental Fig. 4, available at
http://links.lww.com/PAIN/C85);
(3) There was no significant difference in the dropout rates between active and sham stimulation.