Failure to follow prescribed medication regimens is an enormous problem in the United States, costing society nearly $100 billion and leading to an estimated 125,000 deaths every year.

Now, psychology graduate student Sean Young and former psychology graduate student Daniel Oppenheimer, now a professor at Princeton, are publishing a paper suggesting that the problem might be exacerbated by the wording of drug side-effect warnings.

“We found that the way drug information is presented to people leads to a consistent overestimation the likelihood of negative side effects, which in turn increases the likelihood that they will not take their medication as prescribed,” Young says. Young and Oppenheimer’s paper, titled “Presenting Risk Information,” was published in January’s issue of the drug therapy journal ‘Clinical Therapeutics.’

The paper presents the results of three experiments designed to isolate factors that might cause people to avoid their medication. In the first experiment, subjects were asked to estimate their percent chance of suffering ‘commonly reported’ side effects associated with various common prescription drugs. Young and Oppenheimer found that people typically overestimated occurrences by a factor of 10, believing that as many as 20 percent patients experienced side effects like nausea and headache, when the real reported incidence was closer to 2 percent.

When advertising drugs, pharmaceutical companies are required by law to disclose side effects associated with their products. Since direct-to-consumer advertising became legal in the 1990s, companies have consistently preferred ‘semantic’ indicators, which list side effects without being specific about how often they occur.

Young and Oppenheimer, however, showed that subjects who were given percentage risk statistics instead of actual magazine advertisements or stock phrases such as ‘side effects may include’ and ‘some people may experience’ were much more likely to take their medications as prescribed.

The irony is that while drug company marketing practices are designed to increase the purchase of prescription drugs, they are actually making people afraid of their medications.

“This research suggests that framing affects estimates of risk and that current methods of disclosing information are non-optimal,” Young and Oppenheimer write. The result, technically termed ‘medical non-compliance,’ is estimated to cause 125,000 deaths and cost $100 billion.

“Healthcare providers assume that as long as you get info out there to people, it’s less important how it’s communicated,” Young says. “We wanted to show that it makes a huge difference.”

Another problem with the practice of listing ‘most common’ side effects is that it gives a distorted picture of the relative safety of different drug options. In the absence of hard numbers, people estimate the dangers of drugs on the seriousness of their side effects rather than the likelihood of these effects occurring. But while an alarming condition such as hemorrhaging or heart attack might be the most commonly reported side effects for a particular drug, Young pointed out, it may still be extremely rare.

“A ‘most common’ side effect could be fatal, yet be one in a million,” he notes.

The results of the study lead Young and Oppenheimer to make several suggestions that will hopefully lead to decreased medical non-compliance in the future.

They recommend that pharmaceutical companies should distribute drug information with statistics in percentages, noting specifically who is at risk. Certain groups like the elderly and patients on other medications typically report side effects more often than other patients, and while this information is available it is not widely known to the public.

Another option is to standardize the wording of side effect warnings, as is done in the European Union. Side effects would be rated anywhere from ‘extremely rare’ to ‘common,’ labels which would be indexed to percentage risks.

Another psychological method is a ‘ladder scale,’ which compares medication risks with risks of other rare events.

“To give someone an idea of just how uncommon something is, you might compare it to the chances of getting struck by lightning,” Young says.

In the future, Young notes, social psychology has much to offer to policymakers aiming to create a better-informed public.

“One of the big questions in medical decision-making is whether we want a paternalistic system, which gives people less choice,” he says. “Our society has steered away from that. We take the stance that there should be communication between patient and provider to reach a joint decision.”

Unfortunately, consumers often cannot decipher pharmaceutical literature, and drug company advertising practices are little help to informed decision-making.

“Right now we don’t take into account people’s perceptions when they make these decisions,” Young says. “Information needs to be tailored to people’s psychologies.”