Study: Priority Review-Approved Drugs Show Significantly More Problems Post-Approval

More than 34% of drugs approved by Health Canada through its fast-track accelerated review framework ultimately require the addition of serious safety warnings or removal from the market, claims a new research letter published in the Archives of Internal Medicine on 8 October.

The study, by Dr. Joel Lexchin, a professor at York University, looked at 434 new active substances (NASs) approved by Health Canada between 1995 and 2010 and assessed whether they later required the addition of safety warnings or removal from the market.

The NASs were then divided into two groups: those drugs that underwent a standard, 300-day review period and those drugs that underwent a 180-day priority review process.

Drugs that underwent the standard review were later withdrawn from the market acquired a serious safety issue in 19.8% of all cases, while drugs approved via the fast-track pathway acquired serious safety issues in 34.2% of all cases.

"The characteristics of drugs with a priority approval might account for differences in the percentage with safety issues compared with drugs with standard reviews," Lexchin explained. "Drugs are usually assigned a priority review for important clinical problems and may be licensed with a lower benefit to harm threshold, leading to a higher rate of safety warnings."

For Canadian regulators, Lexchin's figures may open up further questions. For instance, is a 72.7% increase in risk relative to a standard review product worth it for all products, or should the standards for fast-track review be tightened?

Lexchin's study notes some products that were not deemed to be "major therapeutic advances" were still given priority review status. "Even drugs that provided no major therapeutic advances were still more likely to acquire serious safety issues if they were put through the priority review," Lexchin said. "This indicates that the difference is likely due to the faster review missing serious safety issues."

Patients and doctors should prescribe-and regulators should track-products approved through the fast-track status more closely, the study ultimately suggests.