Use of Rapid Tests and Antiviral Medications for Influenza
Limited data are available about how physicians diagnose and treat influenza. We conducted an internet-based survey of primary care and emergency physicians to evaluate the use of influenza testing and antiviral medications for diagnosis and treatment of influenza. In April 2005, an electronic link to a 33-question, web-based survey was emailed to members of the American College of Physicians, American Academy of Pediatrics, American Academy of Family Physicians, and American College of Emergency Physicians. Of the 157 674 physician members of the four medical societies, 2649 surveys were completed (1·7%). The majority of participants were internists (59%). Sixty percent of respondents reported using rapid tests to diagnose influenza. Factors associated with using rapid influenza tests included physician specialty, type of patient insurance, and practice setting. After controlling for insurance and community setting, emergency physicians and pediatricians were more likely to use rapid influenza tests than internists [odds ratio (OR) 3·7, confidence interval (CI): 2·3—6·1; and OR 1·7, CI: 1·4—2·1, respectively]. Eighty-six percent of respondents reported prescribing influenza antiviral medications. Reasons for not prescribing antivirals included: patients do not usually present for clinical care within 48 hours of symptom onset (53·0%), cost of antivirals (42·6%) and skepticism about antiviral drug effectiveness (21·7%). The use of rapid tests and antiviral medications for influenza varied by medical specialty. Educating physicians about the utility and limitations of rapid influenza tests and antivirals, and educating patients about seeking prompt medical care for influenza-like illness during influenza season could lead to more rapid diagnosis and improved management of influenza.

Influenza is a contagious, acute febrile respiratory illness associated with an estimated annual average of > 200 000 hospitalizations and 36 000 deaths in the United States. Despite this considerable burden of disease, limited data are available concerning how healthcare providers diagnose and treat influenza in clinical practice.

The accuracy of diagnosing influenza on clinical grounds alone is complicated by the co-circulation of other respiratory pathogens during influenza season that cause symptoms similar to those observed with influenza virus infection. Rapid influenza diagnostic tests allow physicians to obtain prompt results on which to base their treatment decisions. Few guidelines concerning the use of rapid influenza tests are available, and while the number of commercially available rapid tests has increased, little is known about how often and when these tests are used by primary care physicians.

In the United States, four prescription antivirals in two medication classes are available for treatment of influenza: the adamantanes (amantadine and rimantadine), and the neuraminidase inhibitors (oseltamivir and zanamivir). However, the Advisory Committee on Immunization Practices has recommended against the use of adamantanes beginning with the 2005—2006 influenza season because of high levels of adamantane resistance among circulating influenza A viruses. Oseltamivir and zanamivir are approved for treatment of influenza A and B in persons aged ≥ 1 year old and ≥ 7 years old, and for chemoprophylaxis of influenza in persons ≥ 1 year old and ≥ 5 years old, respectively. The efficacy of antivirals for treatment and chemoprophylaxis of influenza has been evaluated in published studies. However, limited data exist regarding primary care physicians' use of antiviral medications for influenza. A cross-sectional study of 336 physicians in Texas and Massachusetts conducted during 2004 found that 61% of doctors had prescribed antivirals within the previous year; a study of 738 primary care physicians in four states during the 2006—2007 influenza seasons found that 53·8% had prescribed antiviral agents. We conducted an internet-based survey to evaluate influenza testing practices, including the use of rapid diagnostic tests, and antiviral prescription use for treatment and chemoprophylaxis of influenza among a large group of US primary care and emergency physicians.