The validity and ethics of giving placebo in a randomized nonpharmacologic trial was evaluated

When studying the effects of a non-pharmacologic intervention, the choice of a control group is often difficult. In a study on the effectiveness of increased water intake on voiding dysfunction in elderly men we used an unusual design. This article addresses the internal validty and ethics of this design.

The randomized trial we evaluated had a 6-month follow-up period and was carried out among 141 elderly men with moderate lower urinary tract symptoms. The experimental group was given the instruction to drink more water, the control group received placebo medication. The participants were not informed that there was a 50% chance of receiving placebo. We measured whether the prior expectations and preferences were comparable for the two study groups, whether blinding was preserved throughout the study period, and whether the participants considered this design ethical.

Prior to randomization, patients had higher expectations for the experimental intervention, but there was not statistically significant difference in their preference. During the study period, two out of 71 patients in the control group unmasked the placebo. In general, both groups fully agreed with the informed consent procedure.

This design can be considered when the effects of a non-pharmacologic interventions are studied.