False Allergy Reports Prompt Needless Penicillin Substitutes

Kate Johnson

November 19, 2014

ATLANTA — Preoperative testing for penicillin allergy in patients with a history of the allergy can significantly reduce the inappropriate use of penicillin alternatives, which contribute to antibiotic resistance and increased morbidity and mortality, according to a study presented here at the American College of Allergy, Asthma & Immunology (ACAAI) 2014.

On the basis of these results from the Mayo Clinic, Jacksonville, Florida, "I believe it would be reasonable to test all presurgical patients who claim to be allergic to penicillin if these patients will be needing perioperative antibiotic therapy," said lead researcher Thanai Pongdee, MD.

However, a study from Canada that was also presented here suggests that even when a penicillin allergy is ruled out in such patients, there could still be barriers to appropriate antibiotic prescription.

At the Mayo Clinic, 384 presurgical patients with a history of penicillin allergy underwent allergy consultation and penicillin allergy skin testing. Of these, 94% had a negative result and were given clearance by the allergist to receive penicillin or cephalosporin antibiotics perioperatively, reported Arveen Thethi, MD, who presented the findings.

"There are a lot of people out there who report a penicillin allergy and are unnecessarily being prescribed a wider-spectrum antibiotic than they really need," Dr Thethi said.

For the patients who tested negative for penicillin allergy, vancomycin use was reduced by 57%, compared with historic control subjects levofloxacin use was reduced by 40%, and clindamycin use was reduced by 22%.

 
There are a lot of people out there who report a penicillin allergy and are unnecessarily being prescribed a wider-spectrum antibiotic than they really need.
 

"If you can work in a multidisciplinary capacity with your colleagues in surgery and anesthesia to come up with a system in which these patients can come to the allergy department as part of their preop evaluation, collectively we can reduce the use of these broader-spectrum antibiotics," said Dr Thethi. "More important, we can let these patients know that they're not allergic, so we really can potentially open up their antibiotic armamentarium."

In the Canadian study, presented as a poster, however, the researchers found that efforts to disprove a history of penicillin allergy were not always successful, particularly if those efforts are not specifically associated with an upcoming surgery.

The retrospective chart review involved 146 consecutive inpatients with a history of penicillin allergy who were seen by a consulting allergist at a teaching hospital during a 1-year period.

The test results were 98.6% negative, as only two patients had their penicillin allergy confirmed, reported lead researcher Rebecca Pratt, MD, from McMaster University in Hamilton, Ontario, Canada.

Despite orders indicating a change in allergy status on the charts of 144 of 145 patients, when 60 of those patients were readmitted to the hospital, 20 were still listed as allergic when only one actually was, reported Dr Pratt.

Charts Not Up-to-Date

"We hypothesized that there would be a significant proportion of charts that would not be amended, despite penicillin allergy testing," she told Medscape Medical News.

"Of the patients who were negative on penicillin skin prick testing and still listed as allergic on the electronic medical record, about half were originally changed to nonallergic following the allergy testing and then changed back," she said.

"This highlights the pitfalls of hospital charting. We believe the reasons behind this could be that the order was not transcribed by the ward clerk to begin with, or that the patients, when readmitted, mentioned that they were allergic to penicillin and the allergy was reinstated," Dr Pratt explained. "It really speaks to the importance of communication with the patient and the family doctor regarding the new allergy status."

The study also showed that 65% of family physicians were not notified of the change in their patient's allergy status.

Of the nonallergic patients who were readmitted without a change to their charts, about half were prescribed antibiotics in the beta-lactam family despite the allergic status noted in the chart.

"Half of those patients [six] were given a cephalosporin and half a piperacillin," she explained. "There is a cross-reactivity of 2% with cephalosporins, so some doctors feel comfortable giving a cephalosporin to an allergic patient, but the six piperacillin patients was surprising and unexpected."

"In general, there may be documentation issues at a number of institutions that make it difficult to remove a reported drug allergy from a patient's medical record," Dr Pongdee told Medscape Medical News.

"At my institution, once a patient has negative penicillin allergy testing, the allergist immediately removes the listed penicillin allergy from the patient's electronic medical record," he explained, so the situation described would not likely occur. However, "I do not know how other institutions remove penicillin allergy from a patient's medical record."

American College of Allergy, Asthma & Immunology (ACAAI) 2014: Abstract P276, presented November 8 and 9, 2014; Abstract 3, presented November 9, 2014.

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