Discussion
In this study, we evaluated the frequency and characteristics of antibiotic allergies at a single SCI center to better identify potential areas for quality improvement when recording drug allergies. A study in the general population used self-reported methods to collect such information found about a 15% prevalence of antibiotic allergy, which was lower than the 29.8% prevalence noted in our study.8
Regarding the most common antibiotic allergies, one study reported allergy to penicillin in the EHR in 12.8% of patients at a major US regional health care system, while 13.1% of patients with SCI had documented allergy to penicillin in our study.9 Regarding the other antibiotic classes, the percentage of allergies were higher than those reported in the general population: sulfonamide (9.6% vs 7.4%), fluoroquinolones (4.5% vs 1.3%), and cephalosporins (4.0% vs 1.7%).10 The EHR appears to capture a much higher rate of antibiotic allergies than that in self-reported studies, such as a study of self-reported allergy in the general adult population in Portugal, where only 4.5% of patients reported allergy to any β-lactam medications.10
The prevalence of an antibiotic allergy could be affected by the health care setting and sex distribution. For example, the Zhou and colleagues’ study conducted in the Greater Boston area showed higher reported antibiotic rates than those in a study from a Southern California medical group. The higher proportion of tertiary referral patients in that specific network was suggested to be the cause of the difference.8,9 Our results in the SCI population are more comparable to that in a tertiary setting. This is consistent with the fact that persons with SCI generally have more exposure to antibiotics and consequently a higher reported rate of allergic reactions to antibiotics.
Similarly, the same study in Southern California noted that female patients use more antibiotics than do male patients, thus potentially contributing to higher rates of reported allergy toward all classes of antibiotics.8 Our study did not investigate antibiotic allergy by sex; however, the significantly higher proportion of male sex among the veteran population would have impacted these results.
Limitations
Our study was limited as a single-center retrospective study. However, our center is one of the major SCI specialty hubs, and the results should be somewhat reflective of those in the veterans with SCI population. Veterans under the US Department of Veterans Affairs (VA) medical care have the option to seek care or procedures in non-VA facilities. If allergies to antibiotics occurred outside of the VA system, there is no mechanism to automatically merge with the VA EHR allergy list, unless they are later recorded and added to the VA EHR. Thus, there is potential for underreporting.
Drug anaphylaxis incidence was noted to change over time.4,8,9 For example, a downtrend of reported antibiotic allergy was reported between 1990 and 2013.10 Our study only reflects an overall prevalence of a single cohort, without demonstration of relationship to time.
Lastly, this study did not aim to differentiate HSRs from other ADRs. This is exactly the point of the study, which investigated the frequency of EHR-recorded antibiotic allergies in our SCI population and reflects the issue with indiscriminate recording of ADRs and HSRs under the umbrella of allergy in the EHR. Further diagnosing true allergies should be considered in the SCI population after weighing the risks and benefits of assessment, aligning with the wishes of the veteran, obtaining informed consent, and addressing the cost-effectiveness of specific tests. We suggest that primary care practitioners work closely with allergy specialists to formulate a mechanism to diagnose various antibiotic allergic reactions, including serum tryptase, epicutaneous skin testing, intradermal skin testing, patch testing, delayed intradermal testing, and drug challenge as appropriate. It is also possible that in cases where very mild reactions/adverse effects of antibiotics were recorded in the EHR, the clinicians and veterans may discuss reintroducing the same antibiotics or proceeding with further testing if necessary. In contrast, the 12% of those with a high risk of severe allergic reactions to penicillin in our study would benefit from allergist evaluation and access to epinephrine auto-injectors at all times. Differentiating true allergy is the only clear way to deter unnecessary avoidance of first-line therapies for antibiotic treatment and avoid promotion of antibiotic resistance.
Future studies can analyze antibiotic allergy based on demographics, including sex and age difference, as well as exploring outpatient vs inpatient settings. Aside from prevalence, we hope to demonstrate antibiotic allergy over time, especially after integration of diagnostic allergy testing, to evaluate the impact to EHR-recorded allergies.