OBJECTIVES: Notoriety bias is defined as “a selection bias in which a case has a greater chance of being reported if the subject is exposed to the studied factor known to cause, thought to cause, or likely to cause the event of interest”. This study aimed to determine the existence of notoriety bias in FDA Adverse Event Reporting System (FAERS) database and estimate its impact on signal strength.

METHODS: Publicly available FAERS data was used for analysis. 31 drugs which had label change/safety alert issued by FDA were considered. These drugs were reviewed four quadrants before and after the safety alert for number of reports, Reporting Odds Ratio (ROR) and Proportional Reporting Ratio (PRR). Wilcoxon signed rank test was used to compare the number of reports and signal strength before and after the alert.

RESULTS: There was increased reporting for 11 drugs after the safety alert/label change by FDA. The reporting of 20 drugs decreased or remained unchanged after the safety alert/label change by FDA. Wilcoxon signed rank test showed that there is no statistically significant difference with respect to the number of reports before and after the safety alert (p: 0.330, Z: -0.974). 14 (45.16%) drugs had increase in ROR, while 17 (54.83%) drugs had decrease in ROR after safety alert issued by FDA (p: 0.953, Z: -0.059). 14 (45.16%) drugs had increase in PRR, while 17 (54.83%) drugs had decrease in PRR after safety alert (p: 0.914, Z: -0.108).

CONCLUSIONS: Although few FDA safety alert/ warnings had strong and immediate impact, many had no impact on reporting of AE and signal strength. This study found that over reporting due to notoriety bias does not exist in the FAERS database and the overall disproportionality in signal estimates is not altered by safety alert.