In the Journals

Patients often prescribed redundant antibiotics

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September 16, 2014

Redundant antimicrobial therapy in hospitals resulted in more than $12 million in potentially avoidable costs, new data suggest.

“Our findings suggest that significant impact can be obtained by focusing on a limited number of combinations that accounted for more than 70% of the unnecessary combinations in our study,” researchers from Premier Safety Institute in Charlotte, N.C., wrote in Infection Control and Hospital Epidemiology. “Metronidazole used with piperacillin-tazobactam [was] the most common inappropriate or redundant combination.”

The researchers conducted a retrospective analysis of administrative data for acute care inpatients from 505 nonfederal US hospitals. They evaluated pharmacy data of inpatients discharged from 2008 to 2011 for use of 23 antibiotic combinations across three categories: anti-anaerobics, anti-MRSA and dual beta-lactams. Lastly, they determined the excess costs resulting from the use of the redundant antibiotics.

Throughout the study period, 32,507 cases received at least 2 consecutive service days of one or more redundant antibiotic therapy, with a mean administration time ranging from 3 to 6 days. Combinations of IV anti-anaerobics were the most common: The most common redundant combination of these drugs was IV metronidazole and piperacillin-tazobactam, which was given to 53% of the sample.

The most common anti-MRSA combination was vancomycin and linezolid (Zyvox, Pfizer), which was given to 5% of the sample. Redundant dual beta-lactam combinations were given to 5% of the patients, and the most common combination was piperacillin-tazobactam and ceftriaxone.

Of the 26,544 cases of redundant IV metronidazole, only 5% of the cases had diagnosis code for Clostridium difficile infection and only 34% of the cases had a recorded test for CDI. Among the 2,917 cases of redundant anti-MRSA agents, only 44% had a diagnosis code for MRSA and only 36% of the cases had a recorded test for MRSA.

The total excess cost for the six redundant anti-anaerobic regimens used if metronidazole is the baseline treatment was nearly $10 million. For anti-MRSA regimens, the total excess cost if vancomycin is the baseline treatment was $855,000 for daptomycin (Cubicin, Cubist Pharmaceuticals) and $1.07 million for linezolid. If daptomycin is the baseline treatment, the excess cost for using linezolid is $336,000.

“Although there may be rare instances where the combinations we examined were appropriate, we believe that the vast majority of these cases represent avoidable duplication,” the researchers wrote. “There is no evidence to support the routine use of any of the combinations we analyzed.”

Disclosure: Four researchers are employees of Premier.

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