To the Editor:
My encounter with an advertisement for an influenza medication in a national newsmagazine prompted me to write this letter. The direct-to-consumer (DTC) marketing of the newly approved antineuraminidase inhibitors contributes to the rapidly expanding world of DTC advertising, which totaled $905 million in the first half of 1999. Influenza is an acute significant respiratory tract infection heralded by an abrupt onset. The 4 approved therapeutic medications (amantadine hydrochloride, rimantadine hydrochloride, zanamivir, and oseltamivir) must be started within 30 to 48 hours of initial symptoms for any appreciable benefit to the patient, yet only a small fraction of patients present to their primary care providers within this time frame. For appropriate use of these medications, early communication with health care providers is crucial. Efforts through recent DTC marketing emphasize this early communication. Consequently, I fear that health care providers will start receiving a large volume of requests for over-the-phone treatments. Complicating the picture are the following:
- Influenza is a common pathogen with relatively high attack rates. In family practices, as much as 11% of patient visits are for influenzalike illnesses during the peak of epidemic influenza.
- Antiviral drugs can be relatively expensive: Amantadine hydrochloride is the lowest-priced agent, and the antineuraminadases are the highest-priced agents.
- Antiviral drugs have modest effects on the course of influenza, reducing the duration of symptoms by approximately 1 day, and they can be accompanied by side effects. Only the antineuraminidases have been shown to have efficacy against influenza B.
- Rapid diagnostic tests are limited and add expense in the outpatient setting. Because influenza is typically not in circulation in the community for 85% of the year, appropriate use of test kits occurs when influenza is known to be in circulation. When used without surveillance—on the basis of viral culture—positive predictive values are quite low.
An appropriate approach to influenza management within family practice includes:
- Using existing, publicly funded influenza surveillance systems to determine if influenza is circulating and what type is predominant. The Centers for Disease Control maintain the “Influenza Summary Update”, which is available through an automated phone-and-fax system (call (888) 232-3299 and request fax document number 231100) or through the Centers for Disease Control Web site (www.cdc.gov.ncidod/diseases/flu/weekly.htm).
- Limiting the use of rapid diagnostic kits because of high rates of false-positives during periods of endemic or absent influenza and false-negatives during epidemics of influenza. If influenza has been proved to be in circulation, diagnoses can usually be made on clinical grounds.
- Encouraging Patients to receive the trivalent influenza vaccine, especially those in high-risk categories and those aged older than 50 years. Medications are no substitute for immunoprophylaxis.
- Establishing clinic protocols to appropriately provide for telephone triage during influenza A epidemics (usually 8 weeks within a given community).
- Using less expensive agents during periods of influenza A predominance. When influenza A and B are coexisting, antineuraminidases may be more effective.
—Jonathan L. Temte, MD, PhD
University of Wisconsin Madison