Table 2.

Sham Methods Used in the 55 Randomized Controlled Trials

Type of sham methods		Points used for sham compare with real interventions	Stimulation of sham methods compare with real interventions	No. of RCTs	References
Type I	Same treatment on ear acupoints that are not theoretically effective for the condition (nonspecific ear acupoints)	Different points	Same stimulation	25	12–14, 17, 20–23, 27–29, 32, 36, 37, 43–46, 48, 51, 57, 59, 60, 64, 66
Type II	Same treatment on nonacupoints on the ear	Different points	Same stimulation	7	19, 38, 40, 41, 50, 63, 65
Type III	Placebo needles or adhesive patches without pellet/seed on the same ear acupoints	Same points	Less or no stimulation	9	25, 42, 52, 54–56, 58, 61, 62
Type IV	Pseudo-interventions (e.g., switched off laser acupuncture devices, electro-acupuncture devices with minimum emission, Vaccaria seeds without pressing) on the same ear acupoints	Same points	Less or no stimulation	10	24, 30, 31, 33–35, 39, 49, 53, 57
Type I+ Type III	Placebo pellets (adhesive patches without pellet/seed) on nonspecific ear acupoints	Different points	Less or no stimulation	2	26, 47
Type I+ Type IV	No electrical stimulation on nonspecific ear acupoints	Different points	Less or no stimulation	1	15
Type II+ Type IV	Electro-acupuncture on nonacupoints on the ear, with pseudostimulation	Different points	Less or no stimulation	2	16, 18

One RCT employed two types of sham methods (Type I and Type IV) in two control arms (Li, 2011 study).