Olanzapine Reduces Violence Risk

Jane Salodof MacNeil

October 31, 2003

Oct. 31, 2003 (Boston) — Duke University researchers found olanzapine (Zyprexa) significantly reduced violent behavior in schizophrenic patients who received the drug for 12 months.

A year of risperidone (Risperdal) therapy did not produce a significant reduction for patients in the three-year study, which followed 124 schizophrenic patients. The results were reported here yesterday in a poster at the American Psychiatric Association's 55th Institute on Psychiatric Services.

"Some of the effect could be adherence to treatment, and that might be a benefit of olanzapine over risperidone," investigator Richard A. Van Dorn, PhD, from Duke's Department of Psychiatry and Behavioral Sciences, told Medscape in an interview.

Dr. Van Dorn said the 59 patients on olanzapine were more compliant with their medication than the 65 patients on risperidone. The investigators do not know why, but they called for research into factors affecting compliance differences between the two drugs, both of which are atypical antipsychotics.

Adherence to treatment was the only factor other than duration of olanzapine therapy to have a significant effect in reducing violence.

"If [olanzapine] is a drug that can improve compliance, I think that can lead to beneficial outcomes, including a reduction in violence," Dr. Van Dorn said, noting that adherence is a major problem in treating schizophrenia.

The patients were drawn from North Carolina sites participating in a larger study, the Schizophrenia Care and Assessment Project (SCAP), from 1997 to 1999. Although some participants were hospitalized during the study, they were mostly followed in outpatient settings.

The olanzapine group included 33 patients aged 20 to 45 years and 26 older patients; 24 women and 35 men; and 40 African Americans and 19 whites. The risperidone group included 30 patients aged 20 to 45 years and 35 older patients; 31 women and 34 men; and 44 African Americans and 21 whites.

Violent incidents and compliance were tracked with several measures, including patient interviews, medical records, and police reports. The process was repeated every six months, with 357 personal observation periods recorded.

More violent patients were in the olanzapine cohort (13 patients vs. 7 patients receiving risperidone). Dr. Van Dorn speculated that violent patients may have been more likely to be switched to olanzapine as inpatients.

For patients receiving olanzapine, he said, the predictive probability of violent behavior decreased from 23 violent incidents per 100 events at six months of therapy to 7 per 100 after 12 months. At six months, the patients receiving risperidone had a lower probability of 12 violent incidents per 100 events. It decreased to 10 per 100 events at 12 months, but the difference was not statistically significant.

"I think it's important to remember violence is a very rare event in this population," Dr. Van Dorn concluded.

This study was funded by Eli Lilly and Co., the maker of olanzapine.

APA 55th Institute on Psychiatric Services: Abstract 21. Presented Oct. 30, 2003.

Reviewed by Gary D. Vogin, MD

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