Primary Care Research

Primary care physicians often prescribe antiviral medications inappropriately or fail to prescribe them when needed

Influenza is responsible for up to 226,000 excess hospitalizations and 36,000 deaths each year in the United States. Flu shots can reduce influenza infections, but vaccination rates remain low. Influenza-specific antiviral medications reduce flu-related symptoms, hospitalizations, and deaths, but are rarely used. For example, a new study, supported by the Agency for Healthcare Research and Quality (HS14420 and HS14563), found that primary care physicians prescribed antiviral medications to only 15 percent of patients diagnosed with influenza. In addition, 30 percent of antiviral prescriptions were inappropriate and 24 percent of patients who met the criteria for antiviral medications did not receive them.

Researchers retrospectively analyzed visits by adults to nine primary care clinics during influenza seasons from October 1, 2000 to May 31, 2004, with a claims diagnosis of influenza (535 people) or with an electronic antiviral prescription (25 people). They defined appropriate antiviral prescribing as the patient having flu symptoms for 2 or fewer days, fever, and any two of the following: headache, sore throat, cough, or myalgias (muscle pain).

The clinical factors associated with antiviral prescribing were not surprising, such as shorter symptom duration (2 vs. 3 days), higher temperatures (37.8 vs. 36.9 degrees C), more myalgias, and more influenza testing. For example, doctors prescribed antiviral medications more often to patients who had myalgias (37 percent) compared with those who did not (18 percent). Doctors also prescribed antiviral medication more often to patients who received an influenza test (67 percent) compared with patients who did not (28 percent).

Non-clinical factors such as race and ethnicity also influenced prescribing. Doctors prescribed antiviral medications more often to blacks (44 percent) and patients of other races or ethnicities (67 percent) than to whites (20 percent) or Hispanics (20 percent). Physicians prescribed amantadine in 10 visits, rimantadine in 9 visits, oseltamivir in 21 visits, and zanamivir in none of the visits.

More details are in "Appropriateness of antiviral prescribing for influenza in primary care: A retrospective analysis," by Jeffrey A. Linder, M.D., M.P.H., Joseph C. Chan, B.S., and David W. Bates, M.D., M.Sc., in the June 2006 Journal of Clinical Pharmacy and Therapeutics 31, pp. 245-252.

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