New UCLA-led study examines content of doctor-patient conversations about dietary supplements

University of California - Los Angeles Health SciencesJul 2 2013

Vitamins, minerals, herbs and other dietary supplements are widely available in supermarkets and drug stores across the nation without a prescription, so it's no surprise that nearly half of all Americans take them.

But they do carry risks, including potentially adverse interactions with prescription drugs, and some people may even use them in place of conventional medications. So it's important that primary care physicians communicate the pros and cons of supplements with their patients. In fact, both the Food and Drug Administration and the National Institutes of Health suggest that patients consult with their doctors before starting to take them.

A new UCLA-led study currently available in the journal Patient Education and Counseling examined the content of doctor-patient conversations about dietary supplements and found that, overall, physicians are not particularly good at conveying important information concerning them.

"This is the first study to look at the actual content of conversations about dietary supplements in a primary care setting," said Dr. Derjung Tarn, an assistant professor of family medicine at the David Geffen School of Medicine at UCLA and the study's primary investigator. "The bottom line was that discussions about meaningful topics such as risks, effectiveness and costs that might inform patient decisions about taking dietary supplements were sparse."

The researchers analyzed transcripts of audio recordings from office visits by 1,477 patients to 102 primary care providers. The data were collected in three separate studies conducted between 1998 and 2010. Of those visits, 357 included patient-physician discussions of 738 dietary supplements. The team found that five major topics were discussed with regard to the supplements: the reason for taking the supplements, how to take them, their potential risks, their effectiveness, and their cost or affordability.

For scoring, the researchers used the Supplement Communication Index (SCI), which is calculated by giving one point for discussion of each of the five major topics.

Among the findings:

• Less than 25 percent of the five major topics - fewer than two on average - were discussed during the office visits.
• All five topics were covered during discussions of only six of the 738 supplements.
• None of the five major topics were discussed for 281 of the supplements patients told their physicians they were taking.
• SCI scores were significantly higher for discussions of non-vitamin, non-mineral supplements such as herbs, compared with those about vitamins and minerals. The former have a greater potential for adverse medication-supplement interactions than the latter.

The researchers pointed out that since the original studies did not focus specifically on dietary supplements, they could not ascertain how many of the 1,477 patients from the three studies were actually taking them. The researchers also did not have information about the patients' medications or medical conditions, so they could not assess if patients were at risk for interactions.

But given these supplements' popularity, easy availability and potential risks, more should be done to improve physician communication about them, the researchers said.

"Future studies should examine the relationship between physician-patient discussions on patient decision-making about dietary supplements, and investigate whether discussions are effective for preventing adverse events and supplement-drug interactions," the researchers write. "A better understanding about these relationships could inform future interventions to enhance physician-patient communication about dietary supplements."