A drug-resistant strain of Salmonella as viewed through a microscope.
This issue brief was updated Aug. 30, 2018, to clarify the conclusions.
Antibiotic resistance is a pressing global public health problem. This first report on trends in antibiotic use in the United States brings together diverse sources of information in both human health care and animal agriculture settings. It complements and informs efforts to set evidence-based goals aimed at reducing unnecessary antibiotic use. Lowering the use of these drugs will slow the emergence of resistance. While today’s data are not perfect, this report begins to establish a baseline and outlines areas where better information is needed. More comprehensive data would allow policymakers to refine priorities, target interventions, and track progress over time.
The U.S. has a relatively high antibiotic prescribing rate. For example, an analysis of 2004 outpatient data from the U.S. and 27 European countries found the U.S. had the fourth-highest rate.1 Although data are incomplete, existing evidence suggests that a significant portion of antibiotic use across U.S. health care settings is inappropriate—from primary care offices and emergency rooms to hospitals and long-term care facilities. Policy options and incentives will vary depending on the setting, but enhanced data are needed across all settings in order to design targeted and effective stewardship interventions that will improve the use and preserve the effectiveness of this valuable resource.
The overall antibiotic prescribing rates for doctors’ offices, emergency departments, and other outpatient settings in the U.S. have decreased in recent years but remain high by international standards. In 2014, for example, outpatient health care providers in the United States wrote over 266 million antibiotic prescriptions, amounting to 835 antibiotic prescriptions for every 1,000 people.2 While that represents a 6 percent decline since 2006,3 this figure was more than 2½ times Sweden’s rate in the same year: 328 prescriptions for every 1,000 people.4 U.S. prescribing rates vary by state, with numbers generally higher in Southern states and lowest in the West.5 (See Figure 1.) Although geographic variation does not clearly indicate differences in the appropriateness of prescribing, it suggests that targeted stewardship has the potential to reduce overall rates of antibiotic use in the U.S. Further research is needed to identify the clinical, socioeconomic, demographic, and other factors driving inappropriate antibiotic use.
Antibiotic prescribing trends vary widely by provider type. For example, prescribing rates for primary care doctors fell by 15 percent from 2011 to 2014, while those for nurse practitioners and physician assistants rose 41 percent.6 The latter figure does not take into account possible changes in patient caseloads—for instance, whether providers are seeing more patients with bacterial infections. However, such differences in trends highlight the importance of implementing comprehensive stewardship initiatives that are directed at all providers. Further research on the drivers behind varied prescribing rates—such as regional variations in patients’ expectations around antibiotic therapy; the availability of education and guidance about antibiotic use and resistance for different providers; economic considerations that influence prescribing practices; and other factors—would furnish important information to help shape targeted antibiotic stewardship efforts.
At least 30 percent of oral antibiotics prescribed in U.S. outpatient settings are unnecessary.7 Of the total excess prescriptions, nearly three-quarters are for acute respiratory conditions, including asthma, allergies, colds, and other infections not caused by bacteria, which therefore do not respond to antibiotics.
In cases where an antibiotic is necessary to treat an infection, it is important to prescribe the appropriate drug. An examination of antibiotic prescribing for three common respiratory conditions found that in about a third of cases, providers selected the wrong drug.8 Choosing an antibiotic that targets only the bacteria most likely to cause a given illness could substantially reduce the development of resistance.9
The three respiratory conditions included in the above study accounted for nearly 30 percent of all antibiotic prescriptions in outpatient settings. Additional data are needed to assess the appropriateness of antibiotic selection for other common conditions managed in such settings.
There are many areas where adequate data on outpatient antibiotic prescribing are lacking. For example, prescribing in retail and urgent care clinics, in dental offices, or via telemedicine is not currently captured. Better data and qualitative research on the drivers of antibiotic use would enable public health agencies, the health care industry, professional societies, and other stakeholders to implement interventions that could improve the appropriateness of prescribing.
Over half of all hospital patients receive antibiotics during their stay—a figure unchanged in recent years.10 However, while the overall rate of hospital antibiotic use has remained steady, the mix of drugs being used has changed. Between 2006 and 2012 specifically, the use of many broad-spectrum antibiotics increased, with a commensurate decrease in use of many narrow-spectrum antibiotics that target a limited group of bacteria.11 As broad-spectrum antibiotics have been shown to significantly increase the risk of drug-resistant infections, this trend is concerning.12
Unfortunately, the U.S. lacks comprehensive data on the appropriateness of inpatient antibiotic use.13 Existing research suggests that improvement is needed. For example, one study examining the treatment of a common bacterial condition (urinary tract infection) and use of a commonly prescribed antibiotic (vancomycin) in a sample of hospitals across the country found that 37 percent of prescriptions were potentially unnecessary or inappropriate (written for the wrong duration or antibiotic).14 In order to have a more complete assessment of the appropriateness of antibiotic use in U.S. hospitals, additional data that capture more conditions and drugs are needed.
The Centers for Disease Control and Prevention has the capacity to track hospital antibiotic use through its National Healthcare Safety Network (NHSN), but currently data reporting is voluntary and limited. As of March 2016, only a small fraction of hospitals report their antibiotic use.15 Mandatory reporting would provide the data needed to establish a more accurate baseline of current use, identify where and what types of stewardship interventions would be most effective, and measure progress toward reducing inappropriate prescribing.
Antibiotics are used in animal agriculture to treat, control, and prevent disease. Currently, little information is publicly available on the volume or appropriateness of that use in the U.S. Experiences in other countries—for instance, through the Monitoring of Antimicrobial Resistance and Antibiotic Usage in Animals in the Netherlands (MARAN) or the European Surveillance of Veterinary Antimicrobial Consumption projects—demonstrate the feasibility and value of collecting data to better understand antibiotic use on farms.16 Collecting such data in the U.S. will be key to establishing a current baseline of use; identifying opportunities to responsibly reduce antibiotic use; setting evidence-based reduction goals; and measuring progress over time.
Collecting nationally representative use data is complicated by the diversity of how industries are structured. For example, the poultry industry is highly integrated whereas the cattle industry is more fragmented, resulting in differences across species in the use of centralized data collection systems.17 Nonetheless, as other countries have demonstrated, enhanced data collection is possible.
The only national estimates of total antibiotic use in U.S. food animal production come from sales data, which can provide insights into trends in use. In 2015, the last year for which data are available, approximately 9.7 million kilograms, or 21.4 million pounds, of antibiotics considered important for human use were sold for use in animal agriculture, a 26 percent total increase over 2009 sales.18 (See Figure 2.) The reason for this increase cannot be determined from available data because sales information does not capture insights on how the drugs were used. Current data also do not break out antibiotic sales by animal species.19 All of these limitations point to the need for additional information to better understand why the sales are trending upward.
National data to evaluate the appropriateness of antibiotic use in animal agriculture are limited. The U.S. Department of Agriculture (USDA) collects nationally representative survey data on animal health, management practices, and productivity. However, the data are collected infrequently (about every five years), and surveys differ widely across species.20 Additional limitations include insufficient quantitative information on reasons for use, and specific drugs, dosages, and duration.21 Without such information, it is difficult to determine why antibiotics are used in U.S. animal agriculture, which uses are appropriate, and where alternatives to antibiotics might be used.
Expanding the USDA’s existing survey to include more detailed questions about the volume of actual use and the dosages, duration, and conditions for which antibiotics are being used would provide the missing information about antibiotic use on farms. This would enable stakeholders to evaluate the impact of recent policy changes, monitor trends, and identify opportunities to improve antibiotic use.
Currently available data on antibiotic use in the U.S. are insufficient. Key stakeholders from the public, private, and nonprofit sectors must work together to improve the quality and availability of data in order to expand antibiotic stewardship in human health care and promote the responsible use of these drugs in food animals. To improve antibiotic use data:
Efforts needed to curb the use of broad-spectrum drugs, slow the spread of resistance
New rule mandates more comprehensive reporting of drugs sold for use in farm animals