Impact of beta-lactam allergy labels on bone marrow transplant patients.

Background: Approximately 95% of patients with a beta-lactam allergy noted in their medical record are not truly allergic when tested. These patients may unnecessarily avoid first-line antibiotics, resulting in increased treatment failure, higher costs, and antibiotic resistance. Bone marrow transplant (BMT) patients may be at higher risk for these adverse outcomes due to weakened immune systems and high risk for severe infections. Our objective was to evaluate beta-lactam allergy labels and their influence on BMT patient outcomes.

Methods: We conducted a retrospective cohort study of adult inpatients undergoing BMT during April 2018-March 2020. Eligibility for penicillin allergy testing/de-labeling was evaluated. Multivariable logistic regression was performed to measure independent effects of beta-lactam allergy labels on 100-day outcomes: mortality, ICU admission, rehospitalization, and intravenous antibiotic use.

Results: Among 358 BMT patients, 75 (21%) had a beta-lactam allergy label at baseline. Mortality was higher in patients with an allergy label (14.7% vs 7.8%, P = 0.067). In multivariable analysis, patients with allergy labels were not at a significantly greater risk of mortality (OR = 1.60; 95% CI = 0.68 - 3.78) but were significantly more likely to receive carbapenems (OR = 6.27; 95% CI = 2.81-13.98). All patients with penicillin-class allergy labels were eligible for allergy testing/de-labeling.

Conclusion: We did not observe a significant increased risk of mortality in BMT patients with beta-lactam allergy labels; however, increased carbapenem use was observed. Penicillin allergy de-labeling programs may help optimize antibiotic prescribing in BMT patients. Larger studies are needed to quantify the impact of beta-lactam allergy labels on BMT patient outcomes.