Profession asks for clarification on risk assessment comment

WASHINGTON — Veterinary and industry officials want the U.S. Food and Drug Administration (FDA) to clarify an agency leader's negative remark aimed at the use of quantitative risk assessment to ascertain antibiotic drug safety.

At presstime, stakeholders cited concern regarding newly appointed FDA Assistant Commissioner for Science Dr. Linda Tollefson's comment to "FDA Week" that the agency might "drop" quantitative risk assessments due to their reportedly slow and arduous nature. "There are no regulations saying one has to be done," she says in the article.

Determining risk

While Tollefson "is not discussing the comment right now," reports FDA spokeswoman Linda Grassie, Dr. Lyle Vogel says he's "puzzled." As director of the American Veterinary Medical Association's (AVMA) Scientific Activities Division, Vogel notes current FDA guidance regarding antimicrobial drugs depends on risk assessment. Rumors the agency might scrap its process follow last month's announcement of an intended withdrawal of Baytril's approval for use in poultry — which ended five years of review — and a three-year risk assessment of virginiamycin. The FDA scrutiny stems from fear of antibiotic resistance problems in people.

When it comes to the controversial use of antibiotics in food animals, quantitative assessment ensures a thorough review, Vogel says.

"I just don't believe that FDA can operate without doing risk assessments quantitatively," Vogel says. "The Baytril assessment took five years because the science wasn't clear on either side. Without risk assessment, what you're left with is an informal review. We need to learn more about FDA's intentions."

Objective standard

While no law or regulation demands FDA perform quantitative risk assessments when considering the removal of drugs, the Animal Health Institute (AHI) and its manufacturing members have pushed the agency to perform such evaluations. Quantitative risk assessment uses models to determine the probability of risk, how likely problems will occur and how severe the health impact. The results are stated in numerical terms, often percentages, and offer an "objective standard," AHI spokesman Ron Phillips says.

"This is a big deal, and people are talking about it," he says. "Without a quantitative risk assessment that gives you data and gives you a measurable risk analysis, you're left with guesswork. Quantitative risk assessment is the best scientific way for setting policy."

Fine-tune the system

As Phillips and other AHI officials mull the organization's response to Tollefson's comments, Dr. Gatz Riddell acknowledges the system, while "essential to making fact-based decisions," might be flawed.

"Maybe some of the work they did was overkill," says Riddell, executive vice president of the American Association of Bovine Practitioners, "but before we drop something that we've become familiar with, let's look at the process and see if we can fix it. There are ways to assess data that doesn't take three years."