A new study reveals that approximately 30 percent of outpatient antibiotic prescriptions in the U.S. between the years 2010 and 2011 were likely unnecessary. The findings highlight the widespread problem of using these medications for conditions that do not require them.

Although antibiotics are effective when prescribed for the right reasons, improper use can lead to antibiotic resistance. Antibiotic resistant infections affect approximately two million people and are connected to 23,000 deaths per year in the U.S. alone.

In the new study, the team used data from the 2010-2011 National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey to estimate the rate of oral antibiotic prescriptions through outpatient care by age and diagnosis. Using this data, they estimated the amount of inappropriate antibiotic use in adults and children in the U.S.

The results revealed that of the 184,032 sampled visits, 12.6 percent of them led to antibiotic prescriptions. Of the diagnoses, sinusitis was associated with the most prescriptions per 1,000 people, followed by ear infections and pharyngitis, a common cause of sore throat.

Overall, acute respiratory infections led to 221 antibiotic prescriptions per year per 1,000 people, but only 111 of them were deemed appropriate. Furthermore, among all conditions and ages from 2010 to 2011 per 1,000 people, approximately 506 antibiotic prescriptions were written per year and only 353 were deemed appropriate.

"Half of antibiotic prescriptions for acute respiratory conditions may have been unnecessary, representing 34 million antibiotic prescriptions annually," the authors wrote. "Collectively, across all conditions, an estimated 30 percent of outpatient, oral antibiotic prescriptions may have been inappropriate."

The team suggests that a 15 percent reduction in overall antibiotic is necessary in order to reduce inappropriate antibiotic use in the outpatient setting by half by the year 2020, as per the goal of the White House National Action Plan for Combating Antibiotic-Resistant Bacteria.

"This estimate of inappropriate outpatient antibiotic prescriptions can be used to inform antibiotic stewardship programs in ambulatory care by public health and health care delivery care systems in the next 5 years," it said.

The findings were published in the May 3 issue of The Journal of the American Medical Association.