Antibiotic Use for Viral Acute Respiratory Tract Infections Remains Common

Antibiotic use for acute respiratory tract infections that are largely viral remains common. Macrolide use has increased since 2007, and 9% of patients received a second antibiotic within 30 days.
Published Online: November 10, 2015
Mark H. Ebell, MD, MS; and Taylor Radke, MPH

Objectives: To determine the type and number of antibiotic prescriptions filled in the 28 days following an index visit for acute respiratory tract infections (ARTIs) generally presumed to be viral.

Study Design: This was a secondary analysis of administrative data.

Methods: We linked administrative data for pharmacy, clinical encounters, and providers to identify all prescriptions for a relevant antibiotic filled within 28 days of an index visit for an ARTI. Data were analyzed descriptively. The primary outcome was whether or not the patient was prescribed an antibiotic or anti-influenza medication for an episode of presumed viral ARTI.

Results: There were 54,656 encounters for presumed viral ARTI. Most visits (84.4%) were to a primary care clinician, with 12% to an urgent care center and 3.6% to the emergency department. Within 28 days of an encounter for a presumed viral upper respiratory tract infection, 49.4% of patients filled an initial antibiotic prescription, 4.8% a prescription for an anti-influenza drug, and 1.2% received both. A second antibiotic prescription was filled after the initial prescription by 8.9% of patients, and a third by 0.7%. Antibiotic use was most common for acute bronchitis (67.8%) and in the urgent care setting (60.2%). Antibiotics were prescribed less often by pediatricians, whereas anti-influenza medications were prescribed most often for patients aged 5 to 17 years by both pediatricians and family physicians. Antibiotic use has increased since 2007, when azithromycin became a generic drug.

Conclusions: Prescribing antibiotics for ARTIs that are likely to be viral in origin remains common, despite extensive public health educational efforts.

Am J Manag Care. 2015;21(10):e567-e575
Take-Away Points
Antibiotic use remains common for viral acute respiratory tract infections. 
  • Antibiotics were most often prescribed for acute bronchitis, in the urgent care setting, and for older patients.
  • Second prescriptions for an antibiotic were given to 9% of patients who received a first prescription.
  • Use of azithromycin has increased since the drug became available as a generic.
Acute viral (upper) respiratory tract infections (ARTIs) are among the most common reasons for a healthcare encounter in the United States, with over 43 million ambulatory visits per year for cough or sore throat, and tens of millions of days of lost productivity.1 Most episodes are caused by viruses, and in otherwise healthy adults, these infections are typically self-limited and do not require a physician visit or a prescription medication. Nevertheless, many patients with uncomplicated, self-limited ARTIs seek care in the emergency department (ED) or primary care office, which subsequently increases healthcare costs and often leads to an inappropriate antibiotic or antiviral prescription.2,3 Medicalization of a self-limited illness makes it more likely that the patient visits a healthcare provider the next time they have an episode of respiratory tract infection (RTI).4

Previous studies have shown that over 60% of adults presenting with ARTI receive an antibiotic; these antibiotics are increasingly broad-spectrum.2,3,5 Episodes of ARTI with cough as the predominant symptom are often labeled “acute bronchitis,” but well-designed randomized controlled trials have shown that azithromycin,6 amoxicillin,7 and amoxicillin-clavulanate8 do not improve outcomes for patients with acute bronchitis. Furthermore, inappropriate overuse of antibiotics and antiviral medications leads to important harms, including antibiotic resistance, which has an impact of $20 billion to $55 billion per year on the US economy.9,10 Patients often experience minor adverse effects such as diarrhea, nausea, urticaria, and rash, which lead to further office visits and time off work. Rarely, they may experience serious complications such as anaphylaxis and clostridium difficile infection.11

Previous studies of prescribing patterns for RTIs used data that were at least 8 years old, measured rates of prescriptions written rather than prescriptions actually filled, and did not gather data on the number of antibiotic prescriptions filled in the month after the initial encounter.2,3,5 The current study addresses those deficiencies and uses a “real-world” data set from a diverse US community.

We used administrative data from a regional health system in the southeastern United States; the vast majority of physicians were in private practice. Although the health system does not track the race of participants, the county in which it is located and from which it draws most of its members is 26.5% African American and 10.4% Hispanic, based on 2010 Census data. No academic medical centers or training programs were part of the system during the study period. We specified a time frame from 2000 to 2012 (the last year for which complete data were available at the time of the data pull) and did not limit by age or sex of the patient. We included any encounter with a primary or secondary diagnosis of an upper RTI that is generally viral in etiology and does not require antibiotic therapy based on evidence-based practice guidelines.12,13 This included acute nasopharyngitis (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 460), laryngitis without obstruction (ICD-9-CM code 464.00), unspecified upper RTI (ICD-9-CM codes 465.0, 465.8, or 465.9), acute bronchitis (ICD-9-CM code 466.0), bronchiolitis (ICD-9-CM codes 466.1, 466.11, 466.19), viral pneumonia (ICD-9-CM codes 480.0, 480.1, 480.2, 480.3, 480.8, 480.9), and influenza (ICD-9-CM codes 487.0, 487.1, 487.8, 488.1).

We excluded any encounters that also had a code for a diagnosis that could reasonably be treated with an antibiotic, including any sinus infection (ICD-9-CM codes 461.0, 461.1, 461.2, 461.3, 461.8, or 461.9), pneumonia (ICD-9-CM codes 481, 482.x, 483.x, 484.x, 485, or 486), acute tonsillitis (ICD-9-CM code 463), streptococcal pharyngitis (ICD-9-CM code 034.0 or 034.1), otitis media (ICD-9-CM code 382.x), mastoiditis (ICD-9-CM code 383.x), orbital cellulitis (ICD-9-CM code 376.0x), and urinary tract infection (ICD-9-CM codes 590.10, 590.11, 595.0, 595.1, 595.9, or 599.0). In order to restrict the sample to patients without chronic lung disease, we excluded any patient with a previous recorded diagnosis of emphysema, chronic bronchitis, bronchiectasis, or COPD (ICD-9-CM codes 491.x, 492.x, 494.x, or 496.x); cystic fibrosis (ICD-9-CM code 277.0x); or interstitial pneumonia (ICD-9-CM code 516.3x). Our general approach is similar to that of the previous study by Grijalva and colleagues.3

For each encounter, we obtained the following administrative data: all diagnostic codes, patient date of birth and gender, date of encounter, clinician specialty, and the site of the encounter. We also recorded the medication name and date for any prescriptions filled within 28 days of the initial encounter.

We combined identical drugs with different trade or generic names. We also calculated the age from the date of birth, and the numbers of days from the initial encounter until each prescription for an antibiotic or anti-influenza drug was filled. We created variables for site of care as primary care office, urgent care, or ED. Due to small numbers of encounters for these specialists, we classified general practitioners as family physicians, and pediatric emergency physicians as emergency physicians. We also created variables for primary care physician (family physician, general internist, or pediatrician) versus other specialty, and for physician assistant or nurse practitioner versus other provider.

The analysis was primarily descriptive. We used the χ2 tests to compare proportions and the Student’s t test to compare continuous variables. All analyses used Stata version 13.2 (StataCorp, College Station, Texas). The primary analysis was for the first or initial prescription(s) filled following the index visit, but we also report data for second or third antibiotic or anti-influenza drug prescriptions filled on subsequent days.

We identified a total of 54,656 episodes of care for a suspected viral ARTI that met our inclusion and exclusion criteria. The mean age of participants was 26.5 years, with a range of 0 to 83 years; 55.9% were female. Children aged under 5 years made up 22.1% of the sample; children and adolescents aged 5 to 17 years, 18.9%; adults aged 18 to 64 years, 57.8%; and only 1.1% were aged 65 years or older. The site of care was urgent care for 12.0%, ED for 3.6%, and primary care for 84.4%. Of visits in the primary care setting, 43.5% were to a family physician, 32.1% to a pediatrician, 24.1% to a general internist, and 0.3% to a physician assistant or nurse practitioner. Data on race or socioeconomic status were not available in our administrative data set, but the region served by the health program is racially and ethnically diverse and includes urban, suburban, and rural areas.

An initial antibiotic prescription was filled by 49.4% of patients and an anti-influenza drug by 4.8% within 28 days of the encounter, with 1.2% receiving both an antibiotic and an anti-influenza drug and 0.3% receiving 2 antibiotics. The percentage of patients receiving an antibiotic or anti-influenza medicine by diagnosis is shown in Table 1. Use of an antibiotic was most common among those with a diagnosis of acute bronchitis (67.8%), although rates were high for all other suspected viral diagnoses (42.2% to 51.4%) other than influenza (14.7%).

Within 28 days of the initial encounter, a second prescription for an antibiotic or anti-influenza medication was filled on a separate day by 2681 patients (8.9% of those who received an initial prescription) and a third prescription was filled by 225 patients (0.7%). The most common combinations by drug class are shown in Table 2. The timing of second prescriptions filled subsequent to the first, and within 14 days of, the initial prescriptions is shown in Figure 1, by days from when the initial prescription was filled. For patients who filled an initial prescription for an anti-influenza drug (including those who also filled a prescription for an antibiotic), the prescription was filled on the same day as the encounter 93% of the time. However, data on the duration of symptoms prior to the clinician encounter were not available.

Time trends of antibiotic and anti-influenza drug use between 2000 and 2012 are shown in Figure 2. Use of any antibiotic decreased from 56% to a low of 45.1% in 2007, but then rose again to a rate of 62% in 2012. Use of anti-influenza medications was more common since 2006 than before for all encounters (6.4% vs 2.7%; P <.001) and for encounters with a diagnosis of influenza (48.3% vs 32.7%; P <.001). Use of specific drug classes by year is shown in Table 3.

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