The latest US census reports a 20% to 30% increase in the population older than 60, which is estimated to double by 2030. Investigations conducted with participants in this population have not kept up with its growth, resulting in a lack of currently available scientific evidence, explains Teodorikez Wilfox Jiménez Rodríguez, MD, MSc. Among the more than 95% of people reporting an allergy to beta-lactam (BL) antibiotics who have been shown to subsequently have good tolerance, elderly patients may do so due to initial false labeling of allergies, the spontaneous loss of sensitivity, or age-related decline in sensitization. This patient population may, thus, be unnecessarily treated with less appropriate antibiotics, causing more side effects and entailing increased health costs.


An Allergological Study

Taking the above into consideration, Dr. Jiménez-Rodríguez and colleagues conducted an allergological study, published in the Journal of Asthma and Allergy, to assess whether patients aged 60 or older with allergy to BLs—some of whom had been previously confirmed—had lost sensitization and could tolerate these antibiotics. “We wanted to see if these patients could finally benefit from receiving first-line antibiotics with less toxic side-effects and less expense to the healthcare system,” adds Dr. Jiménez-Rodríguez.

Study participants were 1) admitted in the participating services and either previously labeled as allergic to BLs or as having hypersensitivity reactions (HSRs) to BLs during a hospital stay or 2) had a history of HSRs to BLs and referred to an outpatient allergy clinic for evaluation. All of these patients were grouped by age into those aged 60-79 (group A) or 80 and older (group B). “Once we identified the patients, we completed a detailed medical history and skin tests with immediate and delayed reading, quantification of total and BL-specific IgE,” says Dr. Jiménez-Rodríguez. “Challenge tests were based on clinical history and skin test results and conducted to confirm or rule out the alleged allergy.”


Exposure-Based Modification

Based on the results of skin and drug challenge testing, the researchers confirmed a final diagnosis of allergy to BL in 27% of patients in group A and 5.4% in group B. Upon multivariable analysis adjusted for sex, atopy, allergy to other drugs, and specific IgE to amoxicilloyl, younger age was found to be an independent risk factor for allergy to BL.

“The culprit drugs for the initial reactions were different and showed changes in consumption patterns,” says Dr. Jiménez-Rodríguez, “since the youngest (group A) were sensitized to frequently used antibiotics like amoxicillin, ampicillin, amoxicillin/clavulanic, and cephalosporins, whereas the older patients (group B) were sensitized mostly to benzylpenicillin, showing that allergy is modified according to exposure.” He notes, however, that immunosenescence could be a possible explanation for the decrease in allergies in group B, adding that additional research is needed to “clarify the mechanisms involved in the production of specific IgE at this age and its clinical significance.”


Valid, Safe & Necessary

Dr. Jiménez-Rodríguez stresses the significance of anaphylaxis as a clinical manifestations of the initial hypersensitivity reactions seen in participants, particularly among group A, due to its severity and the implicit deadly risk (Figure). “Anaphylaxis is related to the culprit drug, and in the case of beta-lactam drugs, it is more frequently triggered by the specific side chains of these agents, so it was logically more common in group A,” he adds. “However, the skin was the organ most frequently involved in reactions, mainly in the form of hives in group A and maculopapular rash in group B. Unsurprisingly, the older the participants were, the greater their limitation to remember the symptoms of their HSRs, supporting previous findings in which it is established that the medical history alone is not enough to establish an allergological diagnosis; hence, the importance of referring patients for an allergological study, even before antibiotics are needed. The allergological study is valid, safe, and must be performed by an allergist before requiring antibiotics, because discarding BL allergy allows patients to be treated better, with safer antibiotics, and with less impact on the healthcare costs.”