US databases indicate psychiatric symptoms lower in influenza patients taking Tamiflu versus those not taking Tamiflu.
Clinical studies have shown similar rates of neurologic and psychiatric events in pediatric influenza patients being treated with Tamiflu compared to those receiving no treatment for their influenza.
Furthermore, recent data derived from US health insurance records2 between 1999-2006 of over 101,000 influenza patients treated with Tamiflu and over 225,000 influenza patients not taking Tamiflu have shown that the Tamiflu treated patients showed a lower likelihood of experiencing a central nervous system (CNS) event such as delirium, delusion, confusion, hallucination, aggressive behaviour etc compared to those not receiving treatment (p<0.001).During the 2005/2006 influenza season the Japanese Ministry of Health Labor and Welfare coordinated a scientific study on the occurrence of influenza-associated symptoms. In accordance with previous clinical trials data the study reported no increase in neuropsychiatric events in patients with influenza receiving Tamiflu versus those not receiving the drug3.Influenza is a serious, sometimes life-threatening disease and the infecting virus gives rise to a number of unpleasant symptoms including a high fever (40 degrees or more), tender joints/limbs, severe malaise, a racking cough and in some cases delirium, confusion and general disorientation. Influenza associated delirium and neuropsychiatric disorders are not uncommon and occur in the United States in approximately 4 of every 100 000 influenza patients in the US, resulting in hospitalization4.The incidence in Japan is believed even higher. A recent survey based on 1219 Japanese pediatric patients reported abnormal behavior in 1.7% of the patients5. A second study reported 50 Japanese pediatric patients hospitalized for influenza. The most common reason for hospitalization was “abnormal behavior” (28%)6.Eduard Holdener, Roche?s Chief Medical Officer, said: “Patient safety is a primary concern for Roche and since the introduction of Tamiflu, Roche has continuously monitored and reviewed post-marketing safety information and provides regular updates to the regulatory agencies”.Roche is aware that a number of reports have been received in Japan of neuropsychiatric symptoms including delirium, with associated abnormal behavior, and very rare cases of death in patients suffering from influenza who have also been taking the antiviral Tamiflu. The Japanese Ministry for Health and Welfare stated that they see no causal relationship between these cases and Tamiflu.Tamiflu has now been used in over 45 million influenza patients worldwide2 and treatment with Tamiflu has proven successful in reducing the duration and severity of the disease. Post marketing surveillance has confirmed that rates of neuropsychiatric events in patients with influenza also taking Tamiflu are uncommon, occurring in around 1 in 37,000 patients2. In addition, reports of such events leading to death are extremely rare, occurring in around 1 out of every 5 million influenza patients treated2. No causal link between such events and Tamiflu has been established.