The pursuit of scientific knowledge sometimes requires clinical investigators to deceive their subjects. Deception is necessary when accurately informing subjects could bias their responses, thereby impairing the validity of the data. Although deception is associated most commonly with psychological research, it occurs in clinical research as well.
In a study of chronic obstructive pulmonary disease, investigators attached a chronolog to subjects' inhalers to measure whether they were "dumping" study medications.1 To ensure accurate measurements, subjects "were not informed of the chronolog's date- and time-recording capabilities." In a study of continuous positive airway pressure (CPAP) vs placebo in sleep apnea, subjects were told that the inert pill placebo was "intended to improve airway function."2 The investigators used a misdescribed pill placebo as the control out of concern that subjects who were familiar with CPAP would have been able to distinguish real CPAP from sham CPAP.
Wendler D, Miller FG. Deception in the Pursuit of Science. Arch Intern Med. 2004;164(6):597-600. doi:10.1001/archinte.164.6.597