Identification and Characteristics of Time-Related Shifts in Suicide-Related Event Frequency During Smoking Cessation Treatment with Varenicline

Objectives: To survey time-related shifts in number of suicide-related events (SRE) during smoking cessation treatment with varenicline (VAR) in cases from the U.S. Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS), as well as the characteristics of these shifts. Methods: We isolated cases from the FAERS database involving VAR usage where SRE was reported as an adverse event (SRE+/VAR+ case) and established a histogram of SRE+/VAR+ case numbers per week. Furthermore, we focused on "cases reporting specific adverse events prior to drug usage start" using X-bar and R chart concepts. We also attempted to exclude the influence of smoking history from the created histogram. Moreover, we constructed a histogram on central nervous system adverse events, which were frequently seen during VAR usage. Results: By removing the effects of smoking history, SRE onset signals were detected over a long period from the start of VAR use. However, expression signals for nausea and abnormal dreams were detected only in the early VAR administration period. Discussion: These results suggest that VAR use-induced SRE is expressed over a long timeframe from the start of treatment. Additionally, the period of SRE expression signal detection was longer than that of the other central nervous system adverse events (nausea and abnormal dreams). Therefore, SRE onset must be carefully monitored during smoking cessation treatment with VAR over the entire treatment period.