Prescriptions for antibiotics outpaced those for antiviral medications by 2 to 1 among patients with confirmed influenza at several care centers during the 2012-2013 flu season, according to a new study.
The findings, published today in Clinical Infectious Diseases, show that many patients at high risk of developing complications from the flu missed out on antiviral medications’ potential benefits. At the same time, others were exposed to adverse effects from antibiotics that offered them little or no benefit and contribute to antibiotic resistance.
The investigators analyzed data from 6766 patients treated for acute respiratory illness at 5 ambulatory care centers in the US Influenza Vaccine Effectiveness Network. Participants in the study were at least 6 months old, had a cough for not more than 7 days, and were tested for influenza with polymerase chain reaction (PCR).
Among all participants, 7.5% received a prescription for an antiviral medication—oseltamivir or zanamivir, which are neuraminidase inhibitors that specifically target the influenza virus. Of the entire group, 35% had PCR-confirmed influenza.
However, the investigators noted that few clinicians adhered to published guidelines. Antiviral medication is recommended for patients whose flu symptoms began within the previous 2 days and have risk factors for developing complications: being aged 2 years or younger or 65 years or older, pregnant, morbidly obese, or having 1 or more chronic illnesses, including compromised immunity.
But only 19% of the 1021 high-risk patients in the study who presented within 2 days of symptom onset were prescribed antiviral medications. Among the 2366 participants with PCR-confirmed influenza, 15% received an antiviral prescription. Of the 1825 patients with PCR-confirmed influenza for whom antiviral and antibiotic data were available, 30% were prescribed an antibiotic and 16% received an antiviral prescription. Antibiotic prescribing data covered amoxicillin-clavulanate, amoxicillin, and azithromycin.
The investigators noted that antiviral prescribing patterns varied widely among the 5 study sites, from 9% to 19% of patients with PCR-confirmed influenza. Antiviral prescriptions also were less frequent among children than adults, including high-risk children younger than 2 years.
In an accompanying editorial, Michael G. Ison, MD, MS, of the Northwestern University Feinberg School of Medicine in Chicago, wrote that the study “clearly demonstrates that antiviral treatment was underutilized and antibacterial therapy was likely overutilized by clinicians caring for outpatients with influenza.”
Ison added that a particularly troubling aspect of the findings “is that these [participants] were seen at centers with expertise in influenza research that should, theoretically, be more attuned to the importance of antiviral therapy, particularly in the high-risk [patients].”
He also noted that the study may underestimate antibiotic prescriptions for influenza because, in addition to the 3 for which data were available, other antibiotics such as cephalosporins and fluoroquinolones may be prescribed for acute respiratory infections. The drugs not only contribute to major public health risks from antibiotic resistance, they also expose patients to the risk of adverse effects including diarrhea and severe inflammation of the colon caused by Clostridium difficile infection.
The study’s authors wrote that their findings “reinforce the need for continuing education on the appropriate use of antibiotic and antiviral agents for patients presenting with acute respiratory illness.”