Feasibility, Benefits, and Limitations of a Penicillin Allergy Skin Testing Service

Analysis of a beta-lactam allergy assessment protocol challenging diverse reported allergies managed by an antimicrobial stewardship program

Objective

To assess the safety and efficacy of a novel beta-lactam allergy assessment algorithm managed by an antimicrobial stewardship program (ASP) team.

Design

Retrospective analysis.

Setting

One quaternary referral teaching hospital and one tertiary care teaching hospital in a large western Pennsylvania health network.

Patients or participants

Patients who received a beta-lactam challenge dose under the beta-lactam allergy assessment algorithm.

Interventions

A beta-lactam allergy assessment protocol was designed and implemented by an ASP team. The protocol risk stratified patients' reported allergies to identify patients appropriate for a challenge with a beta-lactam antibiotic. This retrospective analysis assessed the safety and efficacy of this protocol among patients receiving a challenge dose from November 2017 to July 2021.

Results

Over a 45-month period, 119 total patients with either penicillin or cephalosporin allergies entered the protocol. Following a challenge dose, 106 (89.1%) patients were treated with a beta-lactam. Eleven patients had adverse reactions to a challenge dose, one of which required escalation of care to the intensive care unit. Of the patients with an unknown or low-risk reported allergy, 7/66 (10.6%) had an observed adverse reaction compared to 3/42 (7.1%) who had an observed reaction with a reported high-risk or anaphylactic allergy.

Conclusions

Our implemented protocol was safe and effective, with over 90% of patients tolerating the challenge without incident and many going on to receive indicated beta-lactam therapy. This protocol may serve as a framework for other inpatient ASP teams to implement a low-barrier allergy assessment led by ASP teams.

Pharmacy-Led β-Lactam Allergy Interview (BLAI) Reduces Duration of Fluoroquinolones Within a Community Hospital

BACKGROUND

Patients with reported β-lactam allergies often receive broad-spectrum antimicrobials and have been shown to experience a variety of negative health consequences, such as increased mortality, costs, readmission, and adverse reactions. Current literature focuses on β-lactam allergy skin testing but lacks evidence on β-lactam allergy interviews (BLAI) when skin testing is unavailable.

OBJECTIVE

This study aimed to test the impact of a pharmacy-led BLAI on duration of fluoroquinolones at a community hospital.

METHODS

A quasi-experimental design with a prospective cohort design and historical control group was used to assess patients with reported penicillin (PCN) allergies in a community hospital. The primary outcome was duration of fluoroquinolones before and after implementation of BLAI. Secondary outcomes included length of stay (LOS), percentage of patients switched to a β-lactam antibiotic, percentage of antimicrobial stewardship recommendations made/accepted, and discrepancies between allergy in medical record and interview-reported allergy. Nonparametric continuous data and medians were evaluated by Mann-Whitney U.

RESULTS

A total of 80 patients were included in the study (43 in the control group and 37 in the prospective group). Fluoroquinolone duration was reduced after the implementation of BLAI (3.7 vs 2.7 days, P = 0.027). In all, 49% of patients in the prospective group were switched to a β-lactam antibiotic after BLAI, with no allergic reactions, adverse effects, or impact on LOS. Conclusion and Relevance: BLAI resulted in a significant reduction in fluoroquinolone duration in patients with PCN allergies and may represent a safe and effective option for institutions lacking skin-testing capabilities.

Penicillin skin testing in methicillin-sensitive staphylococcus aureus bacteremia: A cost-effectiveness analysis

Background

Beta-lactams are the mainstay for treating methicillin-susceptible Staphylococcus aureus (MSSA) infections complicated by bacteremia due to superior outcomes compared with vancomycin. With approximately 11% of inpatients reporting a penicillin (PCN) allergy, many patients receive suboptimal treatment for MSSA bacteremia.

Objective

Evaluate the cost-effectiveness of penicillin skin testing (PST) in adult patients with self-reported PCN allergy in an inpatient setting undergoing treatment for MSSA bacteremia.

Methods

A decision analytic model was developed comparing an acute care PST intervention to a scenario with no confirmatory allergy testing. The primary outcome was the incremental cost-effectiveness ratio (ICER) from the health-sector perspective over a 1-year time horizon using quality-adjusted life years (QALYs) as the measure for effectiveness. One-way and probabilistic sensitivity analyses were conducted to assess the uncertainty of the ICER estimation.

Results

Over a 1-year time horizon, PST services applied to all MSSA bacteremia patients reporting a PCN-allergy would result in a cost per patient of $12,559 and 0.73 QALYs while no PST services would have a higher cost per patient of $13,219 and 0.66 QALYs per patient. This resulted in a cost-effectiveness estimate of -$9,429 per QALY gained. Varying the cost of implementing PST services determined a break-even point of $959.98 where any PST cost less than this amount would actually be cost saving.

Conclusions

Patients reporting a PCN allergy on admission may receive sub-optimal alternative therapies to beta-lactams, such as vancomycin, for MSSA bacteremia. This economic analysis demonstrates that inpatient PST services confirming PCN allergy are cost-effective for patients with MSSA bacteremia.