Biocreep:  a possible phenomenon in which so-called noninferiority trials, which compare the efficacy of new drugs with that of existing drugs, in fact allow inferior treatments to go to market.

Noninferiority trials, used predominantly in cases in which testing a new drug against a placebo would be unethical, were used in a quarter of new drug tests submitted to the Food and Drug Administration for review from 2002 to 2009. These trials are designed to determine whether the difference between the latest drug and the existing one, dubbed an active control, is “small enough to allow the known effectiveness of the active control to support the conclusion that the new test drug is also effective,” according to the FDA. Yet the U.S. Government Accountability Office recently found cause to investigate the FDA’s definition of “small,” since some noninferiority margins allowed for as much as a 20% lower effectiveness rate compared with the active control. Though no evidence of biocreep was found, the FDA is tightening regulations to prevent the approval of drugs that are no more effective than a placebo.