Nearly 1 in 4 Antibiotic Rx Still Inappropriate in US

Troy Brown, RN

January 17, 2019

Almost one quarter (23.2%) of outpatient antibiotic prescriptions in the United States are inappropriate, according to an analysis of new diagnosis codes and insurance claims data from 19.2 million patients.

"This study provides the most recent and comprehensive estimates of outpatient antibiotic appropriateness in the US privately insured population to date. Our results show the scale of inappropriate antibiotic prescribing at both the prescription and population levels," the researchers write.

Kao-Ping Chua, MD, PhD, Department of Pediatrics, Child Health Evaluation and Research Center, University of Michigan Medical School, Ann Arbor, and colleagues published their findings online January 16 in BMJ.

The researchers used a 2016 commercial claims and encounters database with data for individuals aged 0 to 64 years who are beneficiaries of employer-provided private health insurance.

Previous research on US outpatient antibiotic appropriateness has relied on pre-2015 data that used diagnosis codes from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), which was replaced by ICD-10-CM in the United States on October 1, 2015.

As in prior studies, the researchers classified each diagnosis code according to the likelihood that antibiotics were appropriate. Specifically, they classified diagnosis codes "as 'always' if the associated condition is almost always an indication for antibiotics (eg, pneumonia or urinary tract infection), 'sometimes' if the condition is a potential indication for antibiotics (eg, acute sinusitis or acute otitis media), and 'never' if the condition is almost never an indication for antibiotics (eg, acute upper respiratory tract infection, acute bronchitis, or non-infectious conditions)," the authors explain.

However, they note that they erred on the side of antibiotic use being appropriate; for example, they classified some codes such as pneumonia as "always" even though it is often viral with no need for antibiotics.

Among all outpatient antibiotic prescriptions filled by patients in the study, 12.8% were appropriate, 35.5% were potentially appropriate, 23.2% were inappropriate, and 28.5% were not associated with a recent diagnosis code.

Acute bronchitis, acute upper respiratory tract infection, and respiratory symptoms were the diagnoses most frequently associated with inappropriate antibiotic prescriptions at a rate of 18.6%, 15.8%, and 14.6%, respectively. (The authors note that the diagnosis codes are not mutually exclusive, such that one patient could have more than one of these commonly used codes.)

"Future studies of outpatient antibiotic appropriateness in the US would be greatly facilitated by the development of a comprehensive ICD-10-CM based classification scheme. Such a scheme could be adapted for use in countries outside the US, many of which have been using a modified version of ICD-10 for decades," the researchers write.

The findings leave unanswered questions, the authors observe. "Our results highlight the importance of conducting future studies to assess the 64.0% of outpatient antibiotic prescription fills that are either only potentially appropriate or not associated with a recent diagnosis code."

The researchers have disclosed no relevant financial relationships.

BMJ. Published online January 16, 2019. Abstract

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