U. PITTSBURGH (US)—Improved drug coverage under Medicare Part D has led to an increase in the use of antibiotics by seniors, particularly of brand-name and more expensive drugs, according to a new study.

“Overuse of antibiotics is a common and important problem that can lead to medical complications and drug resistance,” says Yuting Zhang, assistant professor of health economics at the University of Pittsburgh.

“One of the key questions we sought to answer with our study is how improved prescription drug coverage under Part D affects the usage of these drugs.”

The study, published in the journal Archives of Internal Medicine, suggests while recent changes in drug coverage have improved the use of antibiotics for pneumonia, they could also lead to unnecessary spending on and overuse of expensive and/or inappropriate broad-spectrum antibiotics.

Researchers looked at more than 35,000 Medicare beneficiaries and compared their use of antibiotics two years before and after the implementation of Medicare Part D, which reduced out-of-pocket drug spending between 13 and 23 percent.

Antibiotic use increased most among beneficiaries who lacked drug coverage prior to enrolling in Medicare Part D. Beneficiaries who previously had limited drug coverage also were more likely to fill prescriptions for antibiotics after enrolling in Part D. The largest increases were found in the use of broad-spectrum, newer, and more expensive antibiotics.

The use of antibiotic treatment for pneumonia tripled among those who previously lacked drug coverage, which researchers say is encouraging given the high mortality associated with community-acquired pneumonia among the elderly.

However, antibiotic use for other acute respiratory tract infections (sinusitis, pharyngitis, bronchitis, and non-specific upper respiratory tract infection) for which antibiotics are generally not indicated, also increased.

“When drug coverage is generous, people are more likely to request and fill prescriptions for antibiotics, which may lead to misuse,” says Zhang.

“Although many interventions have helped curb antibiotic prescribing for acute respiratory tract infections and other conditions, our study indicates there may still be substantial room for improvement through education and changes in reimbursement practices to reduce inappropriate use of these drugs.”

The study was funded by the National Institutes of Health and the Agency for Healthcare Research and Quality.

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