The use of the FDA’s Adverse Event Reporting System (FAERS) for broad post-approval drug safety studies has long been curtailed due to three assumed limitations of the dataset. AdverseEvents has systematically set out to debunk all three of these myths through the use of peer-reviewed studies in major academic journals. This blog article summarizes our findings and we invite you to review our complete journal articles for more details.


1. The Weber Effect

Myth: The reporting rate for new drugs is significantly higher than older drugs

The differential rate of reporting within FAERS makes it impossible to compare new drugs to old drugs on a post-approval safety basis. The commonly held assumption is that there is a spike in reporting of adverse events in the two years following FDA approval, followed by a consistent decline in the following years. Referred to as the ‘Weber Effect’, this differential rate of reporting makes it impossible to use FAERS in comparative drug safety studies.


Myth Debunked

In a peer-reviewed study published in the journal Drug Safety in March 2014, AdverseEvents completed the first modern and broad test of the Weber Effect. We found no such reporting pattern. In fact, the general adverse event reporting pattern revealed in the study was that of increasing case counts in the first three calendar quarters after approval followed by relatively constant counts thereafter. The study clearly demonstrated that modern FAERS does not suffer from the Weber Effect.

Download Weber Effect Published Research (pdf)

2. Stimulated Reporting

Myth: FAERS reports are influenced by outside factors

It is widely assumed that stimulated reporting is a major influence on FAERS. This allegedly occurs when FDA alerts, media reports, lawsuits or other outside factors cause certain drugs to receive larger than normal amounts of adverse event reports. The influence of these outside factors degrades the reliability and consistency of data quality needed for in-depth post-approval drug safety studies using FAERS.


Myth Debunked

In a peer-reviewed study published in the journal Drug Safety in September 2014, AdverseEvents completed the first modern and broad test of the effects of Stimulated Reporting on FAERS.   The study examined both the overall and adverse event specific reporting both before and after 100 randomly selected FDA safety alerts and found no discernable pattern of increased or changed reporting as a result of FDA safety alerts. The report clearly demonstrates that modern FAERS does not suffer from the biases of stimulated reporting.

Download Stimulated Reporting Published Research (pdf)

3. Under Reporting

Myth: Vast majority of adverse events are not reported in FAERS

FAERS is a largely voluntary, self-reporting dataset. Because of this, it is widely assumed that only a fraction of the actual serious side effects that occur every year are reported in FAERS. A GAO article published in 2000 estimated that only 1-10% of serious adverse events were reported. This huge level of under-reporting makes the use of FAERS impossible for post-approval drug safety studies.


Myth Debunking in Process

The AdverseEvents scientific team is in the midst of a modern and broad test of the assumptions underlying the under-reporting myth. While it is certainly true that FAERS does not capture every incident of a serious drug adverse event, our initial findings indicate that the overall reporting rate is much higher in modern FAERS than the currently assumed 10%, and even higher still in certain widely used drug classes. A complete peer reviewed journal article on our study is pending.


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Brian Overstreet

Brian Overstreet


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Topics: FAERS

Brian Overstreet

Written by Brian Overstreet