true acupuncture (313 patients), sham acupuncture
(339 patients), or standard therapy (308 patients). The
primary outcome showed a mean reduction of 2.3 days of
headaches in the true acupuncture group, 1.5 days in the
sham acupuncture group, and 2.1 days in the standard
therapy group. The proportion of responders, defined
as patients with a reduction of migraine days by at least
50%, 26 weeks after randomization, was 47% in the true
acupuncture group,