The risks of attempted suicide, completed suicide, and violent suicide showed “no clinically meaningful variation” by the type of antidepressant used in a large cohort study.
“Our finding of equal event rates across antidepressant agents supports the U.S. Food and Drug Administration's decision to treat all antidepressants alike in their advisory” warning that the drugs might be associated with an increase in suicidal thoughts and behaviors, said Dr. Sebastian Schneeweiss of Brigham and Women's Hospital, Boston, and his associates (Arch. Gen. Psychiatry 2010;67:497-506).
Some studies have suggested that particular antidepressant drugs or drug classes raise the risk of suicide to a greater degree than others, but other studies have refuted that. “We sought to address whether the risk of suicide is equal across antidepressant classes and agents after adjusting for selection factors—or whether there are particular regimens with safety advantages that should be prescribed preferentially,” the investigators said.
They studied all adult residents of British Columbia who initiated the use of an antidepressant medication between 1997 and 2006. They excluded patients who used buproprion because it is sometimes used for smoking cessation rather than depressive symptoms, escitalopram because it was not marketed until near the end of the study period, and duloxetine because it was not marketed in Canada during the study period.
The medications were classified as selective serotonin reuptake inhibitors (SSRIs) (citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline); serotonin norepinephrine reuptake inhibitors (venlafaxine); tricyclics (amitriptyline, amoxapine, clomipramine, desipramine, doxepin, imipramine, maprotiline, nortriptyline, protriptyline, and trimipramine); newer and atypical agents (mirtazapine, nefazodone, and trazodone); and monoamine oxidase inhibitors (moclobemide, phenelzine, and tranylcypromine).
A total of 287,543 adults were assessed for 1 year. About 5% had been hospitalized previously for a psychiatric condition, and 0.6% had made a previous suicide attempt.
During the first year, 846 adults attempted suicide (751 adults) and/or completed suicide (104 adults), yielding an event rate of 6.06 attempted and completed suicides per 1,000 person-years, they wrote.
There were no significant differences in suicide rates among antidepressant classes or among individual antidepressants. This finding held true when the data were restricted to cases of suicide attempt only, suicide completion only, and violent suicide only.
Although some researchers have posited that some antidepressants might raise suicide risks only in the first few months after they are initiated, Dr. Schneeweiss and his associates found similar results—no differences among the various antidepressants—even when the data were truncated to only 6 months of follow-up.
In initial analyses, a higher rate of suicidal events in venlafaxine users was found compared with SSRI users, but this effect was attenuated when further, more refined analyses were performed. This suggests that there was a confounding effect with venlafaxine, perhaps related to the tendency of clinicians to prescribe venlafaxine for more severe cases of depression.
The findings reinforce that “treatment decisions should be based on efficacy, and clinicians should be vigilant in monitoring after initiating therapy with any antidepressant agent,” they said.
This study was funded by the National Institute of Mental Health. No financial conflicts of interest were reported.