Background: 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 the FDA Adverse Event Reporting System (FAERS) database and estimate the impact of potential notoriety bias induced by safety alerts on signal estimation using disproportionality analysis. Methods: Publicly available FAERS data were downloaded and used for analysis. Thirty-one drugs which had label change/safety alert issued by FDA from 2009 to 2013 were considered. These drugs were reviewed 4 quarters before and after the safety alert notification for the existence of notoriety bias. The impact of notoriety bias induced by safety alerts was analyzed by comparing the signal strength using reporting odds ratio (ROR) and proportional reporting ratio (PRR), 2 years before and after the safety alert. Wilcoxon signed rank test was used to determine whether there were a statistically significant difference before and after the safety alert. Results: There was increased reporting for 11 drugs after the safety alert/label change by the FDA. The reporting of 20 drugs decreased or remained unchanged after the safety alert/label change by the 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 = .330, Z = −0.974). Fourteen (45.16%) drugs had an increase in ROR, while 17 (54.83%) drugs had a decrease in ROR after safety alert issued by FDA ( P = .953, Z = −0.059). Fourteen (45.16%) drugs had an increase in PRR, while 17 (54.83%) drugs had a decrease in PRR after safety alert issued by the FDA ( P = .914, Z = −0.108). Conclusion: Although few FDA safety alert/warnings had a strong and immediate impact, many had no impact on reporting of AE and signal strength. This study found that overreporting due to notoriety bias does not exist in the FAERS database and the overall disproportionality in signal estimates is not altered by the safety alert.

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Background: Signal strength for any drug event combination can be determined using disproportionality analysis. Vemurafenib is a BRAF inhibitor approved by the US Food and Drug Administration (FDA) in 2011 for the treatment of metastatic melanoma. This study aims to identify the signal strength of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) associated with vemurafenib using disproportionality analysis in FDA database of Adverse Event Reporting System (FAERS). Methods: Data were obtained from the public release of data in FAERS. Case/non-case method was adopted for the analysis of association between vemurafenib use and DRESS. The data mining algorithm used for the analysis was Reporting Odds Ratio (ROR) and Proportional Reporting Ratio (PRR). A value of ROR-1.96SE>1, PRR≥2 were considered as positive signal strength. Results: A total of 7,171 reports for DRESS have been reported in the FDA database. Amongst which 125 reports were associated with vemurafenib. A cumulative ROR of 17.72 (95% CI 14.83; 21.18) and PRR of 17.46 (95% CI 14.65; 20.81) were observed. Combination treatment of vemurafenib with cobimetinib had higher number of reports (100) with ROR of 103.42 (84.13- 127.14) and PRR of 94.52 (78.26- 114.15). Four deaths were reported and the non-death serious reports included hospitalization, life-threatening, disability, and other serious events with 61, 11, 2 and 39 reports respectively. Conclusion: Positive signal strength was observed for vemurafenib associated DRESS. The signal strength was higher for vemurafenib in combination with cobimetinib than vemurafenib alone. Health care professionals should be cautious about encountering serious adverse events and should be reported to the regulatory authorities.

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