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Challenges in herbal research: a randomized clinical trial to assess blinding with ginger
Suzanna M Zick1, Amy Blume, Daniel Normolle
1University of Michigan, Department of Family Medicine, 715 East Huron Street, Suite 1W, Ann Arbor, MI 48104, USA. szick@umich.edu
Objective:
To assess methods to blind study participants to encapsulated ginger (Zingiber officinale).
Design:
A randomized double-blind placebo controlled trial.
Subjects:
Eighty healthy male and female volunteers.
Outcome Measures:
Whether participants can accurately determine if they receive a ginger or placebo capsule and a bottle filled with ginger or placebo capsules.
Results:
Forty-two subjects correctly identified the capsule they received. Of those who received placebo, over 82% correctly identified their capsule. Only 22.5% of those who received ginger correctly identified their capsule. The likelihood of guessing ginger between the groups was statistically similar (p<0.01). 65% correctly guessed which bottle they had received (p=0.0073). Participants receiving the bottle filled with ginger capsules successfully identified their bottle 75% of the time (p=0.0016) compared to the 55% of the placebo group (p=0.5).
Conclusions:
Volunteers cannot determine which type of individual capsule they receive but can distinguish a bottle filled with ginger capsules.
Related Concept Videos
01:11Blinding
02:07Blind Procedures