25609368
BACKGROUND	When performing clinical trials involving acupuncture , it can be difficult to choose a placebo control .
OBJECTIVE	To validate the Park sham needle for use as a double-blind control intervention .
METHODS	Two different methods were employed .
METHODS	First , a researcher blinded to needle type administered the Park sham or a real needle , chosen at random , on the arms of 16 healthy volunteers .
METHODS	The researcher and the volunteers independently recorded which needle type they thought had been applied at each acupuncture point .
METHODS	Second , 19 patients with shoulder impingement syndrome were randomly assigned to receive acupuncture applied with the real needle or the Park sham needle , once a week for 6 weeks alongside a course of physiotherapy .
METHODS	At the end of the 6 sessions the patients recorded which needle type they thought was being used .
METHODS	The results were analyzed with a Fisher 's exact test .
METHODS	This study was carried out in the Outpatient Department of Physiotherapy in Charing Cross Hospital , London , UK , on healthy volunteers and patients with shoulder impingement pain .
METHODS	The age range was 23 to 54 and 22 to 74 years respectively .
RESULTS	Of the healthy volunteers , there was no difference ( P = 0.23 ) between the number of needles that were correctly ( n = 43 ) or incorrectly identified ( n = 53 ) .
RESULTS	All patients thought that they had received the real needles .
RESULTS	The researcher correctly identified all needles that were applied .
CONCLUSIONS	The researcher delivering the acupuncture recognized the needle type .
CONCLUSIONS	However , both healthy and patient volunteers were blind to the needle type .
CONCLUSIONS	This demonstrates that the Park sham needle is an effective single-blind control .
CONCLUSIONS	It should be noted that the number of patients recruited was small and the study was underpowered to detect an effect of treatment .

