1. Introduction
Beta-lactam (BL) antibiotics are one of the most common causes of drug hypersensitivity [
1,
2,
3]. Approximately 6%-10% of the population reports an "allergy" to penicillin’s (PN), including 15% of hospitalized patients, but allergy work-up excludes hypersensitivity in about 95% of them [
4,
5,
6,
7,
8]. Actual hypersensitivity to cephalosporins (CF) is estimated at <2% [
2], to carbapenems 0.3%-3.7% [
9], while to monobactams is unknown. Hypersensitivity in the BL group may involve a BL ring, a single BL antibiotic or antibiotics with a similar or identical structure of R1 side chain, less often R2 [
10,
11,
12,
13]. Anaphylaxis after BL administration is rare, with a frequency of 46.9 per 10,000 for penicillins and 6.1 per 10,000 for cephalosporins in the general population. At the same time, penicillins are the most common cause of drug-induced anaphylaxis [
14].
The diagnosis of "allergy" to BL antibiotics without verification, is associated with a longer hospital stay, more frequent use of fluoroquinolones, vancomycin and clindamycin, higher rates of
Clostridium difficile, methicillin-resistant
Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) infections compared to patients without the "allergy" label [
15,
16]. "Allergy" to BL antibiotics history is associated not only with negative consequences for the patient, but also for the health care system by increasing the cost of treatment [
17,
18,
19]. Avoidance of BL antibiotics in patients reporting an „allergy” result in a higher risk of treatment failure [
20].
De-labeling involves removing the "allergy" label reported by the patient. There are several de-labeling strategies:
- based only on the medical history, if anamnesis clearly indicates symptoms other than hypersensitivity (e.g., isolated, uncharacteristic gastrointestinal symptoms, headaches, hypersensitivity to BL antibiotics in the family),
- diagnosis based on skin tests with determinants, followed by provocation with a single dose of the drug or in divided doses,
- direct oral drug provocation without prior skin testing [
21,
22].
The choice of de-labeling method is based on the risk stratification. The main goal of risk stratification is to select a group of high-risk patients who require access to specialized diagnostics first. At the same time, due to the rare actual hypersensitivity reactions to BL antibiotics, it is important to select a low-risk group in which de-labeling can be safely performed. Previous European Academy of Allergy and Clinical Immunology (EAACI) recommendations suggested a full allergy work-up in patients with suspected BL antibiotic hypersensitivity, without assessing the severity of the reaction [
23,
24,
25]. Current EAACI position paper recommends risk stratification, assessing time and severity of the hypersensitivity reaction. Despite proposed high and low-risk groups, diagnosis without skin testing is recommended only in a narrow group of patients, which includes pediatric patients with benign maculopapular exanthema (MPE) and patients with palmar exfoliative exanthema [
26]. In the last decade many papers on risk stratification in BL hypersensitivity were published, regarding mainly penicillins [
27,
28,
29,
30,
31]. In contrast, recent United States guidelines suggested several important changes in the recommendations for BL hypersensitivity diagnosis, including direct de-labeling patients with nonspecific symptoms of penicillin hypersensitivity, direct provocation with CF with a different R1 side chain in patients with non-anaphylactic hypersensitivity to CF and anaphylactic hypersensitivity to PN. In patients with a history of unverified non-anaphylactic PN/CF allergy, the use of CF/PN without prior skin testing is suggested. [
4]. Both in the United States and Europe, the number of patients reporting hypersensitivity to BL antibiotics (mainly penicillins) far exceeds the number of specialists who could verify the "allergy" label [
32]. The purpose of this study was to analyze the group of patients reporting hypersensitivity to BL antibiotics and to create a model identifying low-risk patients based on anamnesis.
4. Discussion
Inglis et al. analyzed 5023 electronic databases with reported penicillin ADRs (adverse drug reaction). Among them, penicillin allergy was diagnosed in 4773 (95%) and intolerance in 250 (5%). The most reported drug was "penicillin," "penicillins" or "BL antibiotic" - in 3992 patients (79.5%), and among them amoxicillin was the most common 866 (17.2%). Among 4979 patients, about half of them – 2549 (50.7%) were classified as low risk, 1378 (27.4%) as high risk, while in 1052 (20.9%) the risk could not be assessed [
35]. In a retrospective study by
Albin et al. rash and unknown/undocumented hypersensitivity reaction to penicillins accounted more than half (57.2%) of the hypersensitivity symptoms reported by patients, urticaria 18.9%, angioedema 11.8%, and anaphylaxis 6.8%. At the same time, among patients reporting anaphylaxis, 92.4% had no medical records confirming the reaction [
36].
Vyles et al. analyzed pediatric group of 500 patients, among them 380 (76%) children had symptoms of low-risk hypersensitivity to penicillins. The most reported symptoms were rash 466 (92.8%) and pruritus 203 (40.6%) patients. Among 120 children with at least one high-risk symptom, the most common manifestation of hypersensitivity was angioedema – 50 (10%) [
37]. A similar study was conducted in pediatric group admitted to the emergency department due to hypersensitivity to cephalosporins. In 75 of 128 patients (58.6%), only low-risk symptoms were described, most common symptoms were skin rash and pruritus (73%) appearing at least 6 hours after taking the drug. In the high-risk group, the most common symptom was also a rash, but appearing within 6 hours of BL antibiotic administration [
38].
A study by
Touati et al. conducted between 1992 and 2018 at the Department of Allergology at the Montpellier Clinical Hospital included 476 patients who reported DHR (drug hypersensitivity reaction) after cephalosporin use. Among them, 83 patients reported anaphylactic shock, 85 reported anaphylaxis, and 308 reported "other" reactions, which included urticaria, angioedema, MPE, and severe cutaneous adverse reaction (SCAR) [
39]. Anaphylaxis after cephalosporin administration is rare. In analysis b
y Macy et al. anaphylaxis was reported in 5 out of 901908 oral administrations of cephalosporins and in 8 out of 487630 parenteral administrations of cephalosporins [
40].
In our study, as in the study cited above, patients reporting hypersensitivity to penicillins, mainly aminopenicillins, mostly belonged to the low-risk group, as well as patients who could not identify the specific "penicillin" causing the hypersensitivity. Over the past few decades, the use of parenteral penicillin’s significantly decreased, therefore the incidence of severe hypersensitivity, including anaphylaxis is rare [
41]. On the contrary to the studies cited above, patients with a history of hypersensitivity to cephalosporins, including group A cephalosporins, were significantly more likely to be in the high-risk group. In our study, data regarding group A are similar with the results of a multicenter, retrospective, cohort study by
Yang et al. In their study group I of cephalosporins (ceftriaxone, cefuroxime, cefepime, cefotacsime, ceftyzoxime) were the most common cause of anaphylaxis induced by cephalosporin administration [
42]. In our study, patients reporting hypersensitivity to group C cephalosporins, mainly cefazolin, were mostly in the high-risk group. Similar observations were made by
Bogas et al. in a study that examined a group of 184 patients, among whom 76 (41.3%) had confirmed hypersensitivity. Hypersensitivity was confirmed in all patients reporting anaphylactic shock and the majority reporting anaphylaxis, while in the group with mild reactions, all of the patients reporting skin rush and pruritus, were de-labeled [
43].
In our analysis, patients who reported hypersensitivity to more than one BL antibiotic were significantly more often assigned in the low-risk group. This may be due to the simultaneously use of several antibiotics by patient during infection and the inability to determine which drug caused the reaction. This may be similar regarding non-BL antibiotics and other drugs (most often NSAIDs), although our analysis did not find significant differences between studied groups. Hypersensitivity to drugs from unrelated groups is a rare phenomenon [
44,
45].
A systematic review by
Jagpal et al. revealed inaccuracies in the nomenclature and diagnosis of multiple drug intolerance syndrome (MDIS), multiple drug allergy syndrome (MDAS) and multiple drug hypersensitivity syndrome (MDHS) [
44].
Blumenthal et al. described MDAS as a hypersensitivity reaction with a probable immune mechanism involved, to at least two drugs from different, unrelated groups. The incidence of MDAS was estimated at about 1%, while MDIS was estimated at about 6%. In contrast,
Voelker et al. identified multidrug hypersensitivity as a risk factor for IgE mediated penicillin drug allergy in a pediatric population (OR =2.19, 95% CI 1.3-3.6, p=0.0019) [
46]. The diagnosis of multidrug hypersensitivity, without verification, can be fatal for the patients, as in a situation requiring immediate intervention those patients may be left without antimicrobial treatment options.
In our study, patients reporting several episodes of hypersensitivity to BL were significantly more often assigned to low diagnostic risk group. In the high diagnostic risk group, only 15% reported more than one reaction after administration of BL antibiotic. Probably due to the fear of re-taking a drug that previously caused a hypersensitivity reaction and an unequivocal relationship between the drug and hypersensitivity symptoms, usually with a severe course. Study by
Park et al. concluded that previous administration of any BL antibiotic significantly increased the risk of anaphylaxis in patients reporting hypersensitivity to cephalosporins (p=0.01), but not to penicillins (p=0.23). Interestingly, in multivariate regression, there was no statistical significance between re-exposure to BL antibiotic and increased risk of BL-induced anaphylaxis [
47].
4.1. Characteristics of the Low Diagnostic Risk Group
A diagnostic tool based on anamnesis could help to identify a low-risk patients, who could be safely de-labeled. Complete work-up including skin and provocation tests would not be necessary in the abovementioned group. This would reduce the wait time for diagnosis in priority to high-risk patients.
Australian researchers presented a simple tool "PEN-FAST," which has been validated both internally and by researchers from the United States and Europe [
30], [
48]. In a multivariate analysis involving 622 subjects, four factors associated with penicillin hypersensitivity were summarized. They created mnemonic "PEN-FAST" in which "PEN" indicates penicillin hypersensitivity (2 points), "F" - time since the reaction within five years (2 points), "A" - anaphylaxis/angioedema (2 points), "S" - SCAR (2 points), and "T" - need for therapeutic intervention (1 point). Respondents with less than three points were classified as a low-risk patients. In internal validation, the tool’s sensitivity was estimated at 71%, specificity 79%, PPV 25%, and NPV 96% [
30]. External validation in a group of 995 subjects from three centers showed a sensitivity of 70.4%-87.5%, and NPV of 84.9%-98.4% [
49].
We attempted to create a model based on anamnesis alone, which would characterize low-risk patients using a multivariate logistic regression. In the univariate model, penicillin hypersensitivity, time from drug intake to symptoms >24 hours/unknown, long duration or unknown time from hypersensitivity episode to diagnosis, more than one episode of hypersensitivity to BL antibiotics were significant predictors of being assign to the low diagnostic risk group. Regarding the de-labeled group, the specificity of the tool was estimated at 90%, sensitivity 21.93%, NPV 72.04%, PPV 49.53%. In the multivariate model, the time from drug intake to symptom onset of more than 24 hours and more than one episode of hypersensitivity to BL antibiotics increased the chance of being in the low-risk group by several times. The NPV was 76% and the PPV was 68%.
Similar observations were described by
Chiriac et al. in a study consisting of two parts, a retrospective analysis, based on which a predictive model was created, and a prospective study, in which prepared model was validated. Using logistic regression, sensitivity for the retrospective and prospective models was estimated at 51% and 60%, respectively, specificity at 75% and 80%, PPV at 40% and 57%, and NPV at 83% and 82%. The decision tree model presented high specificity, but low sensitivity <45%. Both methods were unable to accurately predict the occurrence of BL hypersensitivity to antibiotics [
50].
In a multicenter Australian study,
Stevenson et al. presented eight low-risk models. In the most precise model, which included isolated skin rash and a time from hypersensitivity reaction longer than one year, the sensitivity was 80.6%, specificity was 60.8%, and NPV was 94.7% [
51].
Siew et al. identified a cohort of low-risk patients who could not remember the name of the BL antibiotic causing the hypersensitivity reaction, reported a history of no anaphylaxis, and had a hypersensitivity reaction at least one year before diagnosis. In this group, the medical history data had a comparable negative predictive value for the occurrence of type I hypersensitivity to BL antibiotics (98.4%), as negative skin test results (98.9%) [
52].
The algorithm based on anamnesis proposed by
Soria et al. showed high sensitivity (92.7%) with low specificity (35.8%) and NPV of 96.3% [
53].
Devchand et al. developed a validated tool that can be used by non-allergist physicians to make further diagnostic decisions based on risk stratification. The tool takes into account data from the patient’s history and laboratory test results [
31,
54,
55].
In a recently published study,
Dunham et al. presented a digital tool designed to simplify decision-making for physicians from other specialties, in patients with a history of BL antibiotic hypersensitivity. The tool encourages appropriate antibiotic selection in groups at low and moderate risk groups, and to be extra cautious in high-risk groups [
56].
Telemedicine is also usable in the risk stratification of BL antibiotic hypersensitivity. It does not completely replace diagnostics, but by identifying low-risk patients who can be safely de-labeled without an in-person visit, it can reduce waiting times to see a specialist and costs to the healthcare system [
57,
58].
Limitations of our analysis include its retrospective, single-center nature. Some complaints reported by patients, such as shortness of breath, are subjective are not verifiable, therefore those patients may have been misclassified into particular risk groups. Expanding the study with pediatric population would increase the value of this study. In conclusion, obtained data may improve the knowledge on risk stratification in patients hospitalized due to suspected BL hypersensitivity. Further research is needed to identify risk factors for BL antibiotic hypersensitivity and to enable the development of more precise, easily accessible diagnostic tools for removing the label of BL allergy. This would result in both health benefits for the patient and financial benefits for the healthcare system. The diagnostic tool based only on anamnesis, does not clearly identify low-risk patients, who could be safely de-labeled.