A survey of physicians found that 73 percent incorrectly believed an FDA approval meant a drug had comparable effectiveness to an approved medication and 70 percent incorrectly believed the FDA required a statistically significant and clinically important effect before approving a drug.

In addition, 52 percent incorrectly believed the FDA required strong evidence such as a randomized trial when giving a medication a “breakthrough” designation. Specialists were more likely to answer questions correctly compared with internists.

Lead researcher Aaron S. Kesselheim, MD, JD, MPH, of Brigham and Women’s Hospital in Boston, and colleagues published their findings online in JAMA on April 12.

“Physicians tended to overestimate the minimum evidence of efficacy required of new drugs,” they wrote. “Similarly, many misinterpreted the term breakthrough—believing these drugs were supported by stronger evidence than required by the statute.”

The researchers mentioned that the FDA can approve medications based on their superiority to placebo and not an active comparator or standard of care. In 2012, the FDA created the “breakthrough” designation for drugs that have an advantage over existing therapies based on preliminary clinical evidence. From 2012 through April 2015, the FDA gave 76 drugs its “breakthrough” designation.

For this study, the researchers selected a random sample of 300 internists and 900 specialists in endocrinology, hematology and infectious diseases from the American Board of Internal Medicine’s diplomate list. They asked the physicians three questions about FDA approvals and five about breakthrough therapies.

Physicians then chose to prescribe two identical drugs: one met the definition of a breakthrough therapy but the other did not. They were then randomized to read one of four versions of a mock FDA press release on the hypothetical drug for lung cancer.

Of the 1,148 physicians contacted, 60 percent responded. The mean age was 46, and 45 percent of respondents were women and 79 percent were specialists. The mean age of non-respondents was 49, while 43 percent were women and 80 percent were specialists.

The researchers found that physicians preferred the hypothetical drug with the breakthrough designation (Axabex) versus the hypothetical drug that was the same but had no breakthrough designation (Zykanta).

In addition, 61 percent of physicians who received a press release that listed the data used for FDA approval said the drug had a strong evidence of benefit compared with 48 percent of physicians who received a press release that said the drug had been granted a breakthrough designation but also mentioned the drug’s effect on survival was unknown.

The researchers noted that their results might not be generalizable beyond internists and the specialists included in this study. They also said surveys have inherent biases. 

“The misconceptions identified may lead physicians to overprescribe newly approved drugs—particularly breakthrough therapies— and inadequately communicate how well these drugs work to the patients who will use them,” they wrote.