A new study found that those taking antidepressants were 2.5 times more likely to attempt suicide than those taking placebo.

Throughout the past two decades, studies have warned of increased suicide rates in those taking antidepressants, especially in children and adolescents. Researchers also documented missing data and other problems in the clinical trials that may have obscured the risks of taking these drugs.

However, a study in 2018 contradicted previous findings, suggesting a decreased rate of suicide attempts. That study used a controversial statistical analysis that goes against FDA regulations, and researchers suggest that it could have biased their findings.

Now, a new article has reported on a direct re-test of the 2018 data, using a more conventionally accepted statistical analysis. The research was conducted by Michael P. Hengartner at the Zurich University of Applied Sciences, Switzerland, and Martin Plöderl at the Paracelsus Medical University, Salzburg, Austria. It was published in the journal Psychotherapy & Psychosomatics.

Hengartner and Plöderl argue that the methods used by the previous researchers were flawed and inappropriate for studying this problem. The previous study used PEY (patient exposure years), which uses each year of use as an individual data point. This is used when the risk is presumed to be constant or cumulative (when more years of use makes it more likely to have a side effect).

However, this is inappropriate for studying suicide risk, according to Hengartner and Plöderl. Suicide risk is elevated immediately after beginning a medication, not cumulatively or over the long-term. Therefore, instead, researchers should use each person exposed to antidepressants as a data point. This is the standard used by the FDA, which also considers PEY to be inappropriate for this type of study.

“When hazards are not constant over time, PEY is inappropriate and may obscure a true adverse drug effect, since (attempted) suicide mostly occurs shortly after treatment initiation and not during continuation or maintenance phases,” Hengartner and Plöderl write.

The researchers re-analyzed the data from the previous study, using their simple technique. They assessed the number of people who were exposed to antidepressants, and the number of people who attempted suicide.

They found that when they asked these simple questions, the data was consistent with previous studies: rates of suicide attempts were 2.5 times higher in the people taking antidepressants than in those who were given the placebo.

The raw numbers are even more striking: 206 suicide attempts in people taking antidepressants, versus 28 suicide attempts in people taking placebo.

There were 37 deaths by suicide in the antidepressant group, and only 4 deaths by suicide in the placebo group.

This means that those who took a drug that ostensibly treats their suicidal ideation were far more likely to attempt suicide and die by suicide than those who took a fake pill that did nothing.

According to the researchers, “The data presented herein suggest that antidepressants significantly increase the suicide risk in adults with major depression.”

Editor’s note: The headline and contents of this article have been edited to fix a math error.

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Hengartner, M. P., & Plöderl, M. (2019). Newer-generation antidepressants and suicide risk in randomized controlled trials: A re-analysis of the FDA database. Psychotherapy & Psychosomatics. Published online June 24, 2019. doi: 10.1159/000501215 (Link)