Inappropriate antibiotic prescriptions for Medicare patients have slightly decreased in recent years

Efforts to reduce outpatient antibiotic prescribing may have incurred a shift among options rather than a substantially reduced amount of antibiotic use.

Antibiotic prescriptions among Medicare fee-for-service patients, including likely inappropriate ones, have slightly decreased in number since 2011, a recent study found.

Researchers used administrative claims of 4.5 million fee-for-service Medicare beneficiaries from 2011 to 2015 to assess overall rates of antibiotic prescriptions. They also evaluated rates of potentially appropriate and inappropriate prescribing, rates for each of the most frequently prescribed antibiotics, and rates of antibiotic claims associated with specific diagnoses.

Results were published online on July 27 by the BMJ.

From 2011 to 2014, the number of antibiotic claims decreased from 1364.7 to 1309.3 annual claims per 1,000 beneficiaries but increased in 2015 to 1364.3 annual claims per 1,000 beneficiaries, an adjusted reduction of 0.20% over the full study period (95% CI, 0.09% to 0.30%).

The researchers classified prescribing as potentially inappropriate if claims were associated with diagnoses for which antibiotics are not indicated. Potentially inappropriate claims decreased from 552.7 to 522.1 per 1,000 beneficiaries from 2011 to 2014, an adjusted reduction of 3.9% (95% CI, 3.7% to 4.1%). (Antibiotic claims in 2015 were not linked with diagnoses to avoid bias from coding changes due to the transition from ICD-9 to ICD-10.)

Changes in use differed by antibiotic. The greatest changes were in azithromycin claims per beneficiary (adjusted decrease of 18.5% [95% CI, 18.2% to 18.8%]) and levofloxacin claims per beneficiary (adjusted increase of 27.7% [95% CI, 27.2% to 28.3%]).

Use of azithromycin decreased for each of the potentially appropriate and inappropriate respiratory diagnoses (e.g., pneumonia, sinusitis, viral upper respiratory tract infections, acute bronchitis, asthma and allergy, and other respiratory conditions). Levofloxacin use increased for each of these diagnoses, and use of amoxicillin/clavulanate (which increased overall) also increased for each of the respiratory diagnoses except pneumonia.

The study authors noted limitations, such as the possibility that Medicare fee-for-service beneficiaries may not be representative of the overall U.S. older adult population. They added that the study design could not delineate whether changes in antibiotic use were due to changes in the behavior of individual prescribers or to a changing composition of prescribers with different behaviors.

The results imply that efforts to reduce outpatient antibiotic prescribing may result in a shifting palette, rather than a substantially reduced amount, of antibiotic use, the authors concluded. “Because decades of effort to reduce outpatient antibiotic prescribing have improved the appropriateness of antibiotic use at most incrementally, we propose that stewardship programs instead focus on the apparently more feasible goal of shifting prescribing from newer, broader spectrum drugs to older, narrow spectrum drugs,” they wrote.