A post hoc subgroup analysis was performed within each category to see if there is any regional difference in trial results, but this analysis could not confirm the results of Vickers et al.  which found Asian countries were more likely to produce positive findings in acupuncture studies. In both categories, there was no difference between studies from Asian and non-Asian countries (test for subgroup differences; FD, p = 0.88; DD, p = 0.23; Additional file 1: Appendix 6).