Preventive misconception: Study shows misunderstanding

Misconception could lead participants to take risks

IRBs already are attuned to the dangers of therapeutic misconception, in which research subjects confuse research interventions with personalized medical care. Meaningful informed consent — explaining clearly the potential risks and benefits of participation in a study — is believed to be the best method of combating the problem.

Now researchers are looking at the potential misconceptions surrounding preventive research, and how a false belief in the benefits of a prevention trial may lead participants to take undue risks with their health.

They've coined the phrase preventive misconception to describe the phenomenon and have demonstrated the existence of preventive misconception in a study of patients participating in a vaccine trial.

The results were published earlier this year in the American Journal of Preventive Medicine.

"We wanted to see if a prevention misconception exists and in fact we found one," says Jeremy Sugarman, MD, MPH, MA, Harvey M. Meyerhoff Professor of Bioethics and Medicine at Johns Hopkins University, Baltimore, MD. "We coined the term because we think there are distinctions between therapy and prevention. They seem to have similar manifestations, but we wanted to have a better way of talking about it."

Sugarman says preventive misconception carries very real risks to participants, if they "disinhibit," or refrain from taking preventive care of themselves because of their participation in a prevention trial.

HIV prevention trials

He first began looking at this issue through his work as chairman of the ethics working group of the HIV Prevention Trials Network, which conducts international HIV prevention research.

"If participants believe that an HIV prevention vaccine is going to work, even an experimental one, then they may engage in unsafe behaviors," he says. "When in fact the reason you're doing the trial is because you don't know if it's going to work or not."

Similarly, Sugarman says, preventive misconception could lead patients on an experimental lipid lowering agent to ignore dietary restrictions, or cause participants in a prevention trial for nosocomial infections to slack off on everyday measures such as hand-washing.

Preventive misconception can take two forms:

  • A patient may erroneously believe that he or she is taking the experimental intervention, rather than, say, a placebo vaccine.
  • A patient may overestimate the effectiveness of the intervention.

Subjects can harbor one or both misconceptions about their participation in a prevention trial, Sugarman says.

Finding misconception in a study

In order to test their theory of preventive misconception, Sugarman's team looked at a shingles vaccine trial conducted at Veterans Administration centers across the U.S. They examined the responses to a telephone-based evaluation conducted with subjects who had just completed informed consent in the trial.

They focused on the answers given to two questions: 1) "What are the benefits to you of participating in this study?" and 2) "What is the primary purpose of this study?" The belief was that the answers to those two questions would help determine whether a subject harbored a preventive misconception.

The team developed a tool that raters could use to identify preventive misconception in the subjects' responses. If it was identified, the rater then tried to decide whether the misconception stemmed from an overestimation of receiving the experimental vaccine, or from an overestimation of the vaccine's effectiveness, or both.

Out of a group of 50 participants whose responses were examined, raters identified a clear preventive misconception in 16, or 32 percent. Of that group, six participants were found to have underestimated the likelihood that they would receive a placebo. Twelve overestimated the effectiveness of the experimental intervention.

Sugarman believes that the relatively high rate of preventive misconception is plausible, given estimates of therapeutic misconception that have been made in previous studies.

Having now identified preventive misconception retrospectively in an existing trial, Sugarman says he now wants to find a way to test the theory in prospective studies, and try to link it to disinhibition.

"We're searching for opportunities in which to use this approach," he says.

He says there's little information now about how preventive misconception may cause disinhibition, let alone what strategies might be best for dealing with the problem.

"We know there is some disinhibition in trials," Sugarman says. "But at the same time, we don't know the root causes of it."

It's possible that the same sort of informed consent improvements used to deal with therapeutic misconception might work in this case, but Sugarman says it's too soon to tell.

However, he says, it's not too early for IRBs to be looking at this issue and considering the potential for preventive misconception in the prevention trials they review.

"I think what's really important, if we do nothing else, is that we now provide a language with which people can articulate their concerns and assess whether it exists in other settings —- and if so, what role it might play in building a robust consent process," Sugarman says.

"We want to encourage IRBs to take a look at this so that they can carry out their obligation to protect the rights and welfare of research participants."


Simon AE, et al. Preventive misconception: Its nature, presence and ethical implications for research. Am J Prev Med. 2007;32:370-374.