Abstract
PURPOSE: On 16 December 2008, FDA issued a class warning for antiepileptic drugs and suicidal thoughts and behavior. The purpose of this study was to determine if the antiepileptic drug gabapentin increases risk of suicide attempt in patients to which it was prescribed for various indications. METHODS: We conducted a pharmacoepidemiologic study in which suicide attempt rates were compared before and after gabapentin was prescribed. We used the PharMetrics medical claims database to study the relationship between gabapentin and suicide attempts in a cohort of 131,178 patients with a 1-year window of information before and after initial prescription. Patients had diagnoses of epilepsy, pain disorders, bipolar illness, major depressive disorder, schizophrenia, and other psychiatric disorders. RESULTS: Overall, there was no significant difference in suicide attempt rates before (3.48/1000 patient years--PY) versus after (3.45/1000 PY) gabapentin prescription. Pre-prescription suicide attempt rates were five times higher in psychiatric populations compared with non-psychiatric populations leading us to analyze the two groups separately. No drug effect was detected in the non-psychiatric populations. Significant reductions in suicide attempt rates were seen for bipolar disorder (47.85/1000 PY versus 31.46/1000 PY), major depressive disorder (17.30/1000 PY versus 12.66/1000 PY), and other psychiatric disorders (12.84/1000 PY versus 10.14/1000 PY). Person-time analysis revealed an overall significant reduction in suicide attempt rates (2.01/1000 PY on drug versus 2.30/1000 PY off drug). CONCLUSIONS: This study finds that gabapentin does not increase risk of suicide attempts in non-psychiatric populations and is associated with a reduction in suicide attempt risk in patients with psychiatric disorders.