Increased suicide attempt rate among patients interrupting use of atypical antipsychotics

The aim of the study is to investigate whether patients at risk to commit suicide could be identified based on their drug refill patterns.

Data for this study were obtained from the PHARMO system comprising drug-dispensing data linked to hospital discharge records. All patients aged 15-45 years, suspected to suffer from schizophrenia and exclusive users of olanzapine or risperidone were selected. The use of antipsychotics was converted into treatment episodes of uninterrupted use. Therapy non-compliance was defined as a drug holiday of at least 30 days. The follow-up started with a treatment episode of at least 90 days. Relative risks for suicide attempts and 95% confidence limits due to drug holidays were estimated using Poisson regression analyses.

Of 603 patients, 33% interrupted treatment for at least 30 days. An increased suicide attempt rate was observed when comparing uninterrupted and interrupted drug use (20.0/1000 person years vs 72.1/1000 person years, respectively). A four-fold increased risk for attempting suicide among patients with drug holidays was found (RR adjusted for age and gender 4.2, 95% CI: 1.7-10.1) compared to patients without drug holidays.

Patients who do not refill atypical antipsychotics in time can be identified in the pharmacy and are most likely those with an increased risk to commit suicide.