CHICAGO — Contrary to some reports, oseltamivir therapy appears not to affect the incidence of neuropsychiatric events in patients with influenza, according to data presented at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
The study used a large U.S. medical claims database to compare the incidence of neuropsychiatric events in the 30 days after an influenza diagnosis in patients who received oseltamivir versus those given no antiviral treatment.
Recent case reports from a variety of countries have linked oseltamivir to neuropsychiatric events. Although no causality has been established, the product label has been changed to include neuropsychiatric events in the European Union, Japan, Switzerland, and the United States, reported lead investigator Marsha A. Wilcox, Sc.D., and colleagues at i3 Drug Safety, in Waltham, Mass.
From Nov. 1, 1999, through April 30, 2005, 60,267 patients were treated with oseltamivir and 175,933 received no antivirals. The two cohorts were balanced for a variety of baseline variables including age, sex, health plan region, index date, number of hospitalizations, and vaccinations for influenza and pneumococcus during the 6 months prior to diagnosis.
The incidence of any neuropsychiatric event was 3.8% in the oseltamivir group and 4.3% in those not treated with antivirals (exposure-adjusted odds ratio 0.89).
The incidence was also comparable for major neuropsychiatric events (3.4% vs. 3.7%; OR 0.89) and for central nervous system stimulation events (2.5% vs. 2.8%; OR 0.88), the investigators reported.
The conference was sponsored by the American Society for Microbiology.
Dr. Wilcox did not disclose any relevant conflicts of interest.