Supposed Penicillin-Allergic Patients Twice as Likely to Receive Alernative Antibiotics


Hospitalized patients with unverified penicillin allergies may unnecessarily face greater risk of adverse drug events when given broader spectrum alternative antibiotics, according to a new study.

penicillin allergy

Patients with documented penicillin allergies are about twice as likely to receive β-lactam alternative antibiotics, and for the vast majority, these substitutions are likely unnecessary, according to a new study.

In a research letter, published in JAMA Internal Medicine, a team led by investigators at Massachusetts General Hospital and Harvard Medical School examined the association between penicillin allergy documentation and antibiotic use.

“If you have a penicillin allergy documented in your medical record and are hospitalized in the US, you are more likely to receive broader spectrum, sometimes less effective and more toxic antibiotics,” Kimberly G. Blumenthal, MD,MSc, allergist and researcher at Massachusetts General Hospital and Harvard Medical School, told Contagion®. “These altered antibiotic choices may not be needed because 95% of patients who have a documented penicillin allergy have their allergy disproved when formally tested.”

Penicillin allergy evaluation, Blumenthal said, should be considered for the 16% of hospitalized patients on antibiotics with documented penicillin allergy.

The study analyzed data from 10,992 patients hospitalized at 106 Vizient Inc. hospitals from September 2018 through January 2019, including 1741 (16%) who had a penicillin allergy documented in their medical records. Most of those patients with documented penicillin allergies (64%) received alternatives to narrow-spectrum β-lactam antibiotics, compared with 48% of other patients. Narrow-spectrum β-lactam antibiotics were given to 13% of patients with penicillin allergies and 30% of those without.

Patients with documented penicillin allergies were about twice as likely to receive a β-lactam alternative antibiotic, such as vancomycin, fluoroquinolones, macrolides, sulfonamides, tetracyclines, clindamycin, aminoglycosides, and linezolid. The odds of receiving clindamycin and aztreonam or monobactams were especially high among patients with penicillin allergies.

“We did not expect to find that overall use of clindamycin and aztreonam was generally low, but in patients with a documented penicillin allergy, exposure to clindamycin was 6 times more and exposure to aztreonam was over 22 times more,” Blumenthal said. “It therefore was almost like these are antibiotics were reserved for inpatients reporting penicillin allergy in the over 100 hospitals studied. “

“Reducing clindamycin and aztreonam would be a good thing for patients and hospitals, as clindamycin is an antibiotic highly associated with C. diff colitis and aztreonam is both high cost and less effective against some gram-negative bacteria (such as Pseudomonas sp),” she continued.

The association between penicillin documentation and use of alternative antibiotics was greatest among patients receiving antibiotics for urinary tract infection and as prophylaxis for surgical procedures.

At least 90% of the antibiotics substitutions examined were likely unnecessary because very few patients with documented penicillin allergies are truly allergic, highlighting a need for penicillin allergy evaluations as part of antibiotic stewardship programs, the study noted.

“I would like all inpatient providers to think twice about their antibiotic decisions when they prescribe antibiotics to patients who have a documented penicillin allergy,” Blumenthal said. “While we think that avoidance of beta-lactams is the right thing to do because patients have this allergy documented and we are told to ‘first do no harm,’ there is a large body of evidence that supports that choosing alternative antibiotics in these patients results in increased risk of antibiotic resistance, healthcare-associated infections, and adverse events.”

In fact, she added, it may be more harmful to assume the allergy is true and to therefore choose alternative care.

About 1 in 10 individuals have reported penicillin allergies, but only about 10% of these represent true allergies.

Reasons for this discrepancy include low risk of allergic reaction, outgrowing the allergy, or even being mis-labeled as allergic in the first place.

“The next steps consider innovative methods to address the inpatient burden of unverified penicillin allergies in US hospitals,” Blumenthal said. “Penicillin allergy assessments should be studied as a method to improve inpatient antibiotic choices overall and perhaps with targeted initiatives to reduce inpatient clindamycin use, inpatient aztreonam use, and increase first-line surgical prophylaxis.”

A recent report examined a tool to identify low-risk penicillin allergies. The penicillin allergy clinical decision rule called PEN-FAST weighs features associated with actual penicillin allergies included being diagnosed with the allergy 5 or fewer years ago, anaphylaxis/angioedema, severe cutaneous adverse reaction, and treatment being required as a result of the allergy episode.

Another recent study found that a pharmacy-driven allergy assessment led to improved allergy documentation, increased use of β-lactam antibiotics and cost savings.

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