High-risk outpatients with acute respiratory illness infrequently prescribed antivirals for influenza, study finds
Factors associated with antiviral treatment were early presentation to care, presence of fever, positive influenza test result, and presentation within the 2013–2014 and 2014–2015 seasons.
Outpatient clinicians often do not prescribe antiviral treatment for influenza to high-risk patients presenting with acute respiratory illness, a recent study found.
Using data from the U.S. Influenza Vaccine Effectiveness Network, researchers analyzed antiviral prescription and clinical data for 15,972 high-risk patients who sought care for an acute respiratory illness at more than 60 outpatient practices during influenza seasons between 2011 and 2016. All patients were tested for influenza for research purposes, and 20% (3,196 of 15,972) were confirmed to have influenza.
Patients were considered at high risk for influenza-related complications if they were younger than age 2 years, were 65 years of age or older, were pregnant, or had chronic health conditions outlined in the Advisory Committee on Immunization Practices guidelines for antiviral treatment. Patients with a body mass index of 40 kg/m2 or greater and those who reported being Native American, Alaska Native, or Native Hawaiian were also considered to be at high risk.
Results were published online on Oct. 23 by Clinical Infectious Diseases.
Fewer than half of high-risk patients with laboratory-confirmed influenza sought care within two days of symptom onset (40%; 1,292 of 3,196). Of these patients, 472 of 1,292 (37%) received an antiviral prescription, compared to 15% of high-risk patients who presented early (718 of 4,861). Of all high-risk patients, only 6.7% (1,074 of 15,972) were prescribed an antiviral.
Compared to all other age groups, adults ages 65 years and older were least likely to present to care early (38%) and most likely to present more than four days after symptom onset (26%) (P<0.01 for both comparisons). Timing of presentation to care was not significantly different across the five influenza seasons.
Several factors were associated with antiviral treatment: early presentation to care (odds ratio, 4.1; 95% CI, 3.5 to 4.8), presence of fever (odds ratio, 3.2; 95% CI, 2.7 to 3.8), positive influenza test result (odds ratio, 4.4; 95% CI, 3.8 to 5.1), and presentation within the 2013 to 2014 (odds ratio, 2.0; 95% CI, 1.5 to 2.5) and 2014 to 2015 seasons (odds ratio, 1.8; 95% CI, 1.4 to 2.2).
Patients who presented early with a cough and fever were more likely to receive an antiviral prescription than those who presented early with a cough but no fever (21% [577 of 2801] vs. 7% [132 of 1,935]; P<0.01). However, fever was not present in 25% (797 of 3,151) of patients with lab-confirmed influenza who had fever data.
The researchers estimated that in order to treat one patient with lab-confirmed influenza, clinicians needed to empirically treat 3.8 patients overall, 2.8 patients who presented with a cough and fever, and 6.7 patients who presented with a cough but no fever. “This method may help providers make treatment decisions when timely sensitive diagnostic assays are not available and empiric treatment decisions must be made,” the study authors wrote, adding that the number needed to treat is lower in high-risk patients, with or without fever, at the peak of influenza season.
They noted that limitations of the study included potentially limited generalizability of the results to other U.S. outpatient practices, a lack of data on symptoms other than cough and fever, and a lack of information on factors that may have influenced clinical decisions, such as disease severity.