Assessment of the risk of suicide-related events induced by concomitant use of antidepressants in cases of smoking cessation treatment with varenicline and assessment of latent risk by the use of varenicline

Smoking Cessation Treatment (SCT) is a policy that has to be promoted for health economics, and expectations for the success of treatments with varenicline (VAR) are large. However, the Food and Drug Administration (FDA) have issued a warning on VAR-induced depression and suicide. In the present study, utilizing the FDA Adverse Event Reporting System (FAERS), we searched for antidepressants (ADs) used during SCT that cause fewer suicide-related events (SRE) (Study 1). We also investigated whether VAR concomitantly administered with ADs increases the risk of SRE (Study 2). In addition, we investigated whether the use of VAR alone is a latent risk factor of SRE. The backgrounds of cases with and without SRE were matched using the Propensity Score. In Study 1, the highest integrated Reporting Odds Ratio (iROR) was noted in concomitantly administered mirtazapine (iROR 6.98; 95% Confidence Interval (CI) 1.57-30.99), while the lowest ratio was noted in concomitantly administered amitriptyline (iROR 0.59; iROR95%CI 0.23-1.50). Study 2 clarified that SCT increases the risk of SRE in AD-treated cases (iROR 8.02; iROR95%CI 5.47-11.76; not significance). Of ADs concomitantly used during SCT with VAR, amitriptyline and mirtazapine showed the lowest and highest risks, respectively (Study 1). It was clarified that concomitant use of VAR in the treatment of depression with ADs increased the risk of SRE (Study 2). The results of Studies 1 and 2 suggested that the use of VAR alone is a latent risk factor inducing suicide.