Data from clinical trials was previously collected and used in a meta-analysis revealed an association between patients using anti-epileptic drugs and suicidality (broadly defined as an individual that has suicidal ideation, suicidal behavior, or both). An article in the August 2010 New England Journal of Medicine addressed whether this association is significant by using observational data gathered from patients who were treated with epileptic drugs and diagnosed depression or bipolar disorder, and whether there was a correlation with suicide-related events, such as attempted suicides or completed suicides.

The patients in this study were from the United Kingdom, and deemed to be representative of the general population. The authors of this study estimated the incidence rate of the attempted and completed suicides, then employed a logistic regression in order to compute odds rations, then a control for confounding factors (confounding factors are elements that invalidate interpretations of the statistical analysis). In a cohort of just under 5,131,000 people who did not have epilepsy, depression, bipolar disorder, or currently receiving anti-epileptic pharmacological therapy, the calculated incidence of suicide attempts or completions per 100,000 person-years was 15. The calculation for patients who did have epilepsy, but did not receive any anti-epileptic medicine jumped to a 38.2 per 100,000 people. For patients who presented with epilepsy and received medication that calculation per 100,000 people for suicide attempts and completions was 48.2.

While the data presented above suggests an association, these authors further adjusted the statistical analysis in order to determine whether patients with epilepsy, bipolar disorder, and medication, or patients with epilepsy, depression, and medication caused the increase. The results of this adjustment indicated that patients with epilepsy and depression who receive anti-epileptic medication do have a higher number of suicidal events (attempts or completions). Thus, the take-home message from this article is that anti-epileptic medicine, generally speaking, did not increase suicidal events. Rather, epileptics suffering with depression and taking medicine need to be more closely monitored for suicidal events.