Adverse event reporting patterns of newly approved drugs in the USA in 2006: an analysis of FDA Adverse Event Reporting System data.

Background: The Weber effect states that adverse event (AE) reporting tends to increase in the first 2 years after a new drug is placed onto the market, peaks at the end of the second year, and then declines. However, since the Weber effect was originally described, there has been improvement in the communication of safety information and new policies regarding the reporting of AEs by healthcare professionals and consumers, prompting reassessment of the existence of the Weber effect in the current AE reporting scenario.

Objectives: To determine the AE reporting patterns for new molecular entity (NME) drugs and biologics approved in 2006 and to examine these patterns for the existence of the Weber effect.

Methods: Publicly available FDA Adverse Event Reporting System data were used to assess the AE reporting patterns for a 5-year period from the drug’s approval date. The total number of annual reports from all sources, based on the report date, was plotted against time (in years).

Results: In the period from 2006 to 2011, a total of 91,187 AE reports were submitted for 19 NMEs approved in 2006. The highest number of AE reports were submitted for varenicline tartrate (N = 47,158) and the lowest number for anidulafungin (N = 161). Anidulafungin was reported to have the highest proportion of death reports (36 %) and varenicline tartrate the lowest proportion (1.7 %). The classic Weber pattern was not observed for any of the 19 NMEs approved in 2006. While there was no one predominant pattern of AE report volume, we grouped the drugs into four general categories; the majority of drugs had either a continued increase in reports (Category A 31.6 %) or an N-pattern with reporting reaching an initial peak in year 2 or 3, declining and then beginning to climb again (Category B 42.1 %).

Conclusions And Relevance: There have been numerous changes in AE reporting, particularly a huge increase in overall annual report volume, since the Weber effect was first reported. Our results suggest that a Weber-type reporting pattern should not be assumed in the design or interpretation of analyses based on AE reports.