Patients diagnosed with schizophrenia or bipolar disorder are at an elevated risk of suicide attempts and suicidal ideation. Although atypical antipsychotics are effective in treating psychotic symptoms, the risk of suicide attempts and suicidal ideation may differ across these agents. We conducted an analysis on reported rates of suicide-related events associated with the use of atypicals.

Proportional reporting rates (PRR) of suicide attempts from the World Health Organization (WHO) database (through June, 2006) were compared across atypical antipsychotics. Using additional information from FDA's AERS (Adverse Event Reporting System; through March, 2006), similar comparisons were made for suicidal ideation, suicide attempts, and completed suicides.

From the WHO database, the PRR for suicide attempts was lowest for clozapine (1.3) followed by aripiprazole (1.5), risperidone (3.3), quetiapine (4.2), ziprasidone (4.7), and olanzapine (5.2). For AERS, the respective PRRs for suicidal ideation, suicide attempts, and completed suicides were: 1.1, 3.3, and 1.9 for clozapine; 3.2, 4.3, and 2.7 for risperidone; 5.6, 2.9, and 5.4 for aripiprazole; 6.9, 4.4, and 6.4 for ziprasidone; 4.3, 4.5, and 7.2 for olanzapine; and 5.6, 4.2, and 9.3 for quetiapine.

AE reporting systems suffer limitations, which include having a problematic denominator and biased reporting. However, AE reporting is a primary tool used to identify a signal through pharmacovigilance. In the data analyzed, variability across atypical antipsychotics seemed evident, and inconsistencies between data were observed. The reasons for these findings are unclear, but these results warrant further investigation in controlled studies.