• Is That Antibiotic Prescription Really Necessary?

    Study Finds One in Four Prescriptions Are for Inappropriate Indications

    February 14, 2019 04:27 pm News Staff – Inappropriate prescribing of antibiotics continues to be a problem in the United States.

    That's the main finding from a study recently published in The BMJ. The study, "Appropriateness of Outpatient Antibiotic Prescribing Among Privately Insured U.S. Patients," examined prescription data for more than 19 million Americans. It found that nearly one-quarter of the antibiotic prescription fills in 2016 were for inappropriate use of these drugs, and that another 35 percent of the prescriptions written and filled were only "potentially" appropriate.

    Study Design and Demographics

    The authors of the study analyzed outpatient antibiotic prescription data from the Truven MarketScan Commercial Claims and Encounters database for 2016, which contained claims for people ages 0 to 64 years who receive private health insurance through their employer. The study cohort was limited to people who had pharmacy benefit coverage and were continuously insured throughout 2016.

    More than three-quarters of the study population were adults, and almost 52 percent were female. Most enrollees lived in the South (45.8 percent) or Midwest (20.3 percent), and about 88 percent of enrollees lived in urban/suburban areas.

    Just over 7.6 million in the study cohort filled a prescription for antibiotics. About half of those people filled only one antibiotic prescription, but nearly 24 percent filled three or more prescriptions. About 1.8 million prescriptions were filled for infants and children 17 or younger.

    Altogether, the study population filled more than 15 million outpatient antibiotic prescriptions in 2016. The most common antibiotic prescribed was azithromycin (2.9 million prescription fills), followed by amoxicillin (2.8 million fills) and amoxicillin-clavulanate (almost 1.8 million fills).

    Statistically, there was a higher prevalence of prescription fills for antibiotics among people living in rural areas and those in the southern United States. People living in rural areas accounted for 11.8 percent of the total study cohort, but they accounted for 13.2 percent of those who filled at least one antibiotic prescription. Similarly, 45.8 percent of overall enrollees lived in the South, but they accounted for 50.6 percent of antibiotic prescription fills.


    Researchers analyzed outpatient prescription data from 2016 for more than 19 million Americans to determine whether antibiotics were prescribed appropriately.

    The analysis indicated that nearly one quarter of the antibiotic prescription fills were for inappropriate indications, and another 35 percent were only potentially appropriate.

    There was a higher prevalence of antibiotic prescription fills among people living in rural areas and in the southern United States.

    Study Methodology Details

    The researchers developed a novel classification scheme in which they assigned a value to every ICD-10-CM code used in 2016 -- more than 91,000 in all. For each code on a claim, the researchers determined whether prescribing an antibiotic for a given condition was always, sometimes or never justified, erring on the side of assuming the antibiotic was used appropriately when deciding how those code values would be classified.

    The researchers then used the scheme to analyze all of the antibiotic prescription fills for 2016 during a "look-back" period beginning three days before an antibiotic prescription fill and ending the day the fill occurred. The team assigned each fill to one of four mutually exclusive categories:

    • appropriate (if the prescription was associated with at least one "always" diagnosis code),
    • potentially appropriate (if associated with at least one "sometimes" code but no "always" codes),
    • inappropriate (if associated only with "never" codes), or
    • not associated with a recent diagnosis code.

    Appropriateness of Antibiotic Prescriptions

    The researchers determined that more than 1.9 million of the prescription fills were appropriate, 5.5 million were potentially appropriate, and about 3.6 million were inappropriate. More than 4.4 million were not associated with a recent diagnosis code.

    A review of prescription fills by age showed that potentially appropriate prescription fills were more prevalent in children than adults (48.7 percent vs. 31.4 percent), and inappropriate prescription fills were more prevalent in adults than children (25.2 percent vs. 17.1 percent). Overall, the researchers determined that about one in seven individuals filled at least one inappropriate prescription in 2016.

    Regarding inappropriate prescription fills, the three most frequently associated diagnoses were acute bronchitis, acute upper respiratory tract infections and respiratory symptoms such as cough. And mirroring the overall breakdown of most commonly prescribed antibiotics, the antibiotics most frequently prescribed inappropriately were azithromycin, amoxicillin and amoxicillin-clavulanate.

    Most of the inappropriate prescription fills -- nearly 71 percent -- originated in the office setting. Another 11 percent were written in urgent care centers or emergency departments. However, the report did not categorize the number of prescriptions by provider type or specialty.


    "By themselves, these findings would show the widespread nature of inappropriate outpatient antibiotic prescribing at the level of both prescription fill and population," the authors wrote. Given that nearly two-thirds of the prescriptions were classified as only potentially appropriate or were not associated with a recent diagnosis code, however, they suggested that the true number of inappropriate antibiotic prescriptions may be even higher.

    Other study limitations that should be considered include the fact that the analysis relied strictly on diagnosis codes and did not account for inaccurate or incomplete coding of a patient's condition. In addition, prescription fills or office visits that were paid for out-of-pocket were not included in the analysis, and prescriptions to patients covered by public health insurance programs such as Medicare or Medicaid also were excluded.

    Finally, the authors stated that the results of this study highlight the importance of conducting additional studies to address the appropriate use of antibiotics. They also suggested that the classification scheme could be of value to policymakers and other researchers in efforts to reduce antibiotic overuse and improve prescribing methods.

    Resources for Family Physicians

    The AAFP has for decades taken a strong stance on correct use of antibiotics. Its antibiotics policy recognizes that inappropriate use of antibiotics poses a risk to personal and public health and encourages members to prescribe them judiciously.

    The Academy was an inaugural partner in the Choosing Wisely campaign formally launched in 2012 to improve patient care while reducing possible harms from unnecessary procedures and tests.

    To date, the campaign has issued nearly 40 recommendations on appropriate use of antibiotics, all of which are freely available to clinicians and patients. Of particular interest to family physicians are recommendations the Academy submitted on the use of antibiotics for sinusitis and otitis media.

    In addition to the Choosing Wisely recommendations, the Academy offers several other clinical resources and policies on antibiotic use that FPs may find useful.