Optimising the utility of in vitro tests for the diagnosis of drug allergy: insights from a clinical perspective

Purpose of review To outline currently validated in vitro tests for the diagnosis of drug hypersensivity reactions (DHRs) and to provide useful strategies to optimise the utility of these tools. Recent findings Regarding in vitro tests for DHR, the main concern, at present, is low sensitivity. Thus, most of the efforts are currently directed towards improving the existing techniques and developing new assays with better diagnostic performance. Summary The management of DHRs is particularly challenging. Current strategies for diagnosis are focused on taking a thorough clinical history, evaluating sensitization using skin testing and performing supervised challenges. In vitro tests may potentially add information to the diagnostic algorithms for the management of DHRs. The presently available assays, however, pose significant limitations in terms of availability and validation. Maximizing their yield and accuracy, therefore, requires a tailored approach, focused on an appropriate clinical characterisation of the reaction. The time elapsed between drug administration and symptom presentation, as well as symptom duration, should be closely taken into consideration. In this review, existing validated in vitro techniques that may support the diagnosis of both immediate and non-immediate DHRs are summarised. Clues for optimizing their diagnostic yield are given

Quality of Life in Patients with Allergic Reactions to Medications: Influence of a Drug Allergy Evaluation

Background Suspicion of allergic drug reaction can cause important disturbances in the patient's life. Objective We evaluated in a prospective multicenter study the quality of life of patients who suffered a possible allergic drug reaction, and analyzed the effect of a drug allergy evaluation. Methods Patients (>18 years old) answered the specific questionnaire twice: before the drug allergy evaluation, and 1 month after it was completed. Statistics were performed using STATA. Results A total of 360 patients (240, 66.6% female; mean age, 45.4 years; standard deviation [SD], 15.6 years) completed the first questionnaire. After the evaluation, 150 of 346 patients (43.4%) were diagnosed as allergic to the drug (115 of 150 immediate; 35 of 150 delayed) and 196 of 346 patients (56.6%) as nonallergic. The mean value of the first questionnaire was 32.14 (SD, 11.84); patients with anaphylaxis, nonanaphylactic immediate reaction, with more than 1 drug reaction, or a chronic osteoarticular disease, had a statistically significant higher score in Q0 (worse quality of life). After the allergy study, the mean of the second questionnaire was 27.27 (SD, 9.96), showing a global improvement (P 40 years old (P = .030), having a chronic osteoarticular disease (P = .003) and having more than 1 reaction to drugs (P < .001) were associated with a statistically significant worse quality of life after the evaluation. Conclusions Having suffered anaphylaxis, more than 1 reported drug allergy or presenting a musculoskeletal disease are factors that worsen the quality of life. Quality of life improved significantly after completing a drug allergy evaluation

Clinical management of plant food allergy in patients sensitized to lipid transfer proteins is heterogeneous: identifying the gaps

Background and objective: Patients sensitized to lipid transfer protein (LTP) present a wide clinical variability. The lack of practical diagnostic and therapeutic guidelines complicate their management. The aim of the study was to describe the clinical approach of Spanish allergists to this pathology using a survey designed by PICO method and subsequent Delphi approach validation. Methods: Designed survey was answered by 224 allergists (75% women; 57.1% with >20 years of professional experience). Homogeneity regarding clinical practice on the main points of LTP allergy diagnosis was observed, except for patients with suspected NSAID hypersensitivity (44.6% frequently include LTP skin testing). Oral food challenges were not frequently performed (63.6% occasionally to never), and they were generally (75.5%) used to confirm tolerance. It was common to recommend fruit skins avoidance (77.2%) and maintaining consumption of foods to which patients are sensitised but tolerant (99.1%). Results: There was heterogeneity on other dietary indications, modifications due to co-factors, or traces avoidance. Peach sublingual immunotherapy (SLIT) was considered very/quite effective by 55.9% of allergists. The majority (79.5%) consider SLIT indicated in <25% of LTP allergic patients, based on severity (95.2%), frequency of reactions (99.4%), allergy to multiple food families (97.4%), and the quality of life/nutrition impairment (91.5%). There was different practice on SLIT prescription based on co-factor involvement. Conclusion: These data suggest that there is a need to increase evidence to reduce the clinical practice heterogeneity in the management of LTP allergy

Improvement of the Elevated Tryptase Criterion to Discriminate IgE- From Non–IgE-Mediated Allergic Reactions

BACKGROUND: Differentiating between immunoglobulin E (IgE)-dependent and IgE-independent hypersensitivity reactions may improve the etiologic orientation and clinical management of patients with allergic reactions in the anesthesia setting. Serum tryptase levels may be useful to discriminate the immune mechanism of allergic reactions, but the diagnostic accuracy and optimal cutpoint remain unclear. We aimed to compare the diagnostic accuracy of tryptase during reaction (TDR) alone and the TDR/basal tryptase (TDR/BT) ratio for discriminating IgE- from non–IgE-mediated allergic reac- tions, and to estimate the best cut point for these indicators. METHODS: We included 111 patients (45% men; aged 3–99 years) who had experienced an allergic reaction, even though the allergic reaction could be nonanaphylactic. Allergy tests were performed to classify the reaction as an IgE- or non–IgE-mediated one. The area under the curve (AUC) of the receiver operating characteristic analysis was performed to estimate the discrimi- native ability of TDR and TDR/BT ratio. RESULTS: An IgE-mediated reaction was diagnosed in 49.5% of patients, of whom 56% met ana- phylaxis criteria. The median (quartiles) TDR for the IgE-mediated reactions was 8.0 (4.9–19.6) and 5.1 (3.5–8.1) for the non–IgE-mediated (P = .022). The median (quartiles) TDR/BT ratio was 2.7 (1.7–4.5) in IgE-mediated and 1.1 (1.0–1.6) in non–IgE-mediated reactions (P < .001). The TDR/BT ratio showed the greatest ability to discriminate IgE- from non–IgE-mediated reac- tions compared to TDR (AUC TDR/BT = 0.79 [95% confidence interval (CI), 1.1–2.2] and AUC TDR = 0.66 [95% CI, 1.1–2.2]; P = .003). The optimal cut point for TDR/BT (maximization of the sum of the sensitivity and specificity) was 1.66 (95% CI, 1.1–2.2). CONCLUSIONS: The TDR/BT ratio showed a significantly better discriminative ability than TDR to discriminate IgE- from non–IgE-mediated allergic reactions. An optimal TDR/BT ratio thresh- old of approximately 1.66 may be useful in clinical practice to classify allergic reactions as IgE- or non–IgE-mediated. (Anesth Analg 2018;127:414–9

Improvement of the elevated tryptase criterion to discriminate IgE- from non-IgE-mediated allergic reactions

BACKGROUND: Differentiating between immunoglobulin E (IgE)-dependent and IgE-independent hypersensitivity reactions may improve the etiologic orientation and clinical management of patients with allergic reactions in the anesthesia setting. Serum tryptase levels may be useful to discriminate the immune mechanism of allergic reactions, but the diagnostic accuracy and optimal cutpoint remain unclear. We aimed to compare the diagnostic accuracy of tryptase during reaction (TDR) alone and the TDR/basal tryptase (TDR/BT) ratio for discriminating IgE- from non–IgE-mediated allergic reactions, and to estimate the best cut point for these indicators. METHODS: We included 111 patients (45% men; aged 3–99 years) who had experienced an allergic reaction, even though the allergic reaction could be nonanaphylactic. Allergy tests were performed to classify the reaction as an IgE- or non–IgE-mediated one. The area under the curve (AUC) of the receiver operating characteristic analysis was performed to estimate the discriminative ability of TDR and TDR/BT ratio. RESULTS: An IgE-mediated reaction was diagnosed in 49.5% of patients, of whom 56% met anaphylaxis criteria. The median (quartiles) TDR for the IgE-mediated reactions was 8.0 (4.9–19.6) and 5.1 (3.5–8.1) for the non–IgE-mediated (P = .022). The median (quartiles) TDR/BT ratio was 2.7 (1.7–4.5) in IgE-mediated and 1.1 (1.0–1.6) in non–IgE-mediated reactions (P < .001). The TDR/BT ratio showed the greatest ability to discriminate IgE- from non–IgE-mediated reactions compared to TDR (AUC TDR/BT = 0.79 [95% confidence interval (CI), 1.1–2.2] and AUC TDR = 0.66 [95% CI, 1.1–2.2]; P = .003). The optimal cut point for TDR/BT (maximization of the sum of the sensitivity and specificity) was 1.66 (95% CI, 1.1–2.2). CONCLUSIONS: The TDR/BT ratio showed a significantly better discriminative ability than TDR to discriminate IgE- from non–IgE-mediated allergic reactions. An optimal TDR/BT ratio threshold of approximately 1.66 may be useful in clinical practice to classify allergic reactions as IgEor non–IgE-mediated. (Anesth Analg 2018;127:414–9

Unraveling the Diagnosis of Kiwifruit Allergy: Usefulness of Current Diagnostic Tests

Objectives: To determine the usefulness of the in vitro and in vivo methods used in the diagnosis of kiwifruit allergy and to specifically assess the impact of seed proteins on sensitivity. Methods: We performed skin prick tests (SPTs) using various commercial extracts, homemade pulp, and seed extracts and prick-prick tests with kiwifruit on 36 allergic patients. The presence of specific IgE (sIgE) was assessed using the ImmunoCAP (kiwifruit extract), ELISA (Act d 1, Act d 2), ISAC, and FABER assays. Immunoblotting of seed extract was carried out, and a single-blind oral food challenge was performed with whole seeds in seed-sensitized individuals. Results: The prick prick test with kiwifruit demonstrated the highest diagnostic capacity (81.8% sensitivity and 94.1% specificity) among the in vivo tests. The sIgE levels measured using ImmunoCAP (kiwifruit extract) showed a similar sensitivity to that of global ISAC and FABER (63.9%, 59.5%, and 58.3%, respectively). Act d 1 was the major allergen. Sensitization to Act d 1 was associated with positive sIgE results to whole kiwifruit extract detected by ImmunoCAP (P<.000). A positive SPT result to kiwifruit seeds was associated with severe symptoms induced by kiwifruit (P=.019) as a marker of advanced disease, but not with clinically relevant sensitization. Challenge testing with kiwifruit seeds performed on 8 seed-sensitized patients yielded negative results. Conclusions: Sensitization to Act d 1 is associated with a positive result in conventional diagnostic techniques, whereas kiwifruit seed sensitization does not increase the sensitivity of the diagnostic techniques evaluated.Objetivos: Determinar la rentabilidad diagnóstica de las técnicas in vitro e in vivo utilizadas en el diagnóstico de alergia al kiwi y estudiar la influencia de las proteínas alergénicas de las semillas en su sensibilidad. Métodos: Se seleccionaron 36 pacientes alérgicos a kiwi. Se les realizó prick test con cuatro extractos comerciales diferentes y prick-prick con kiwi. Se determinó IgE específica mediante ImmunoCAP (extracto de kiwi), ELISA (Act d 1, Act d 2), las micromatrices ISAC y FABER e Immunoblotting de extracto de semilla de kiwi. Se realizó exposición oral simple ciego frente a semilla de kiwi en pacientes sensibilizados a la semilla. Resultados: El prick-prick de kiwi fue la prueba in vivo con mayor rendimiento (sensibilidad 81,8%, especificidad 94,1%). El ImmunoCAP de extracto de kiwi mostró una sensibilidad similar a la global del ISAC y del FABER (63,9%, 59,5% y 58,3%, respectivamente). Act d 1 fue el alérgeno mayoritario. Se encontró asociación entre los niveles de IgE específica frente a Act d 1 (ISAC) y el extracto de kiwi mediante ImmunoCAP (p <0,000). La prueba cutánea positiva con semilla se asoció con mayor gravedad de síntomas frente a kiwi (p = 0,019), como marcador de enfermedad avanzada, pero no como sensibilización clínicamente relevante. La prueba de provocación con semillas fue negativa en los ocho pacientes provocados. Conclusiones: La sensibilización a Act d 1 se asocia con resultados positivos con las técnicas diagnósticas convencionales. La sensibilización frente a semillas no mejora el rendimiento de las técnicas evaluadas

Validation of a commercial allergen microarray platform for specific immunoglobulin E detection of respiratory and plant food allergens

Background As the use of multiplex-specific immunoglobulin E (sIgE) detection methods becomes increasingly widespread, proper comparative validation assessments of emerging new platforms are vital. Objective To evaluate the clinical and technical performance of a newly introduced microarray platform, Allergy Explorer (ALEX) (MacroArray Diagnostics), in the diagnosis of pollen (cypress, grass, olive), dust mite (Dermatophagoides pteronyssinus), mold (Alternaria alternata), fruit (apple, peach), and nut (walnut, hazelnut and peanut) allergies and to compare it with those of the ImmunoCAP Immuno Solid-phase Allergen Chip (ISAC) 112 microarray and the ImmunoCAP singleplex method (ThermoFisher Scientific). Methods We enrolled 153 patients with allergy and 16 controls without atopy. The sIgE assays were conducted using ISAC112, ALEX version 2 (ALEX2), and ImmunoCAP for whole extracts and major components. Technical validation of ALEX2 was performed by measuring repeatability and interassay, interbatch, and interlaboratory reproducibility. Results When measured globally (detection by 1 or more allergen components), ALEX2 had adequate sensitivity and specificity for most of the allergens studied, comparable in general with that of ISAC112 (except for olive pollen and walnut) and similar to that of ImmunoCAP whole extract measurements. Component-by-component analysis revealed comparable results for all techniques, except for Ole e 1 and Jug r 3, in both ISAC112 and ImmunoCAP comparisons, and Alt a 1, when compared with ISAC112. Continuous sIgE levels correlate with sIgE by ImmunoCAP. Good reproducibility and repeatability were observed for ALEX2. Conclusion ALEX2 has sound technical performance and adequate diagnostic capacity, comparable in general with that of ISAC112 and ImmunoCAP

Validation of a commercial allergen microarray platform for specific immunoglobulin E detection of respiratory and plant food allergens - Improvement of the Elevated Tryptase Criterion to Discriminate IgE- From Non–IgE-Mediated Allergic Reactions - Validation of novel recipes for masking peanuts in double-blind, placebo-controlled food challenges

Background: As the use of multiplex-specific immunoglobulin E (sIgE) detection methods becomes increasingly widespread, proper comparative validation assessments of emerging new platforms are vital. Objective: To evaluate the clinical and technical performance of a newly introduced microarray platform, Allergy Explorer (ALEX) (MacroArray Diagnostics), in the diagnosis of pollen (cypress, grass, olive), dust mite (Dermato- phagoides pteronyssinus), mold (Alternaria alternata), fruit (apple, peach), and nut (walnut, hazelnut and peanut) allergies and to compare it with those of the ImmunoCAP Immuno Solid-phase Allergen Chip (ISAC) 112 microar- ray and the ImmunoCAP singleplex method (ThermoFisher Scientific). Methods: We enrolled 153 patients with allergy and 16 controls without atopy. The sIgE assays were conducted using ISAC112, ALEX version 2 (ALEX2), and ImmunoCAP for whole extracts and major components. Technical validation of ALEX2 was performed by measuring repeatability and interassay, interbatch, and interlaboratory reproducibility. Results: When measured globally (detection by 1 or more allergen components), ALEX2 had adequate sensitivity and specificity for most of the allergens studied, comparable in general with that of ISAC112 (except for olive pol- len and walnut) and similar to that of ImmunoCAP whole extract measurements. Component-by-component analysis revealed comparable results for all techniques, except for Ole e 1 and Jug r 3, in both ISAC112 and Immu- noCAP comparisons, and Alt a 1, when compared with ISAC112. Continuous sIgE levels correlate with sIgE by ImmunoCAP. Good reproducibility and repeatability were observed for ALEX2. Conclusion: ALEX2 has sound technical performance and adequate diagnostic capacity, comparable in general with that of ISAC112 and ImmunoCAP

Is Microarray Analysis Really Useful and Sufficient to Diagnose Nut Allergy in the Mediterranean Area?

Background: Component-based diagnosis on multiplex platforms is widely used in food allergy but its clinical performance has not been evaluated in nut allergy. Objective: To assess the diagnostic performance of a commercial protein microarray in the determination of specific IgE (sIgE) in peanut, hazelnut, and walnut allergy. Methods: sIgE was measured in 36 peanut-allergic, 36 hazelnut-allergic, and 44 walnut-allergic patients by ISAC 112, and subsequently, sIgE against available components was determined by ImmunoCAP in patients with negative ISAC results. ImmunoCAP was also used to measure sIgE to Ara h 9, Cor a 8, and Jug r 3 in a subgroup of lipid transfer protein (LTP)-sensitized nut-allergic patients (positive skin prick test to LTP-enriched extract). sIgE levels by ImmunoCAP were compared with ISAC ranges. Results: Most peanut-, hazelnut-, and walnut-allergic patients were sensitized to the corresponding nut LTP (Ara h 9, 66.7%; Cor a 8, 80.5%; Jug r 3, 84% respectively). However, ISAC did not detect sIgE in 33.3% of peanut-allergic patients, 13.9% of hazelnut-allergic patients, or 13.6% of walnut-allergic patients. sIgE determination by ImmunoCAP detected sensitization to Ara h 9, Cor a 8, and Jug r 3 in, respectively, 61.5% of peanut-allergic patients, 60% of hazelnut-allergic patients, and 88.3% of walnut-allergic patients with negative ISAC results. In the subgroup of peach LTP–sensitized patients, Ara h 9 sIgE was detected in more cases by ImmunoCAP than by ISAC (94.4% vs 72.2%, P<.05). Similar rates of Cor a 8 and Jug r 3 sensitization were detected by both techniques. Conclusions: The diagnostic performance of ISAC was adequate for hazelnut and walnut allergy but not for peanut allergy. sIgE sensitivity against Ara h 9 in ISAC needs to be improved.Introducción: La utilidad clínica del diagnóstico por componentes no ha sido evaluada en el estudio de la alergia a frutos secos (FS). Objetivo: Evaluar la capacidad diagnóstica de una micromatriz comercial de proteínas alergénicas en la alergia a cacahuete, avellana y nuez. Métodos: Se determinó la sIgE en pacientes alérgicos a FS mediante la micromatriz ISAC 112, e ImmunoCAP en los pacientes con sIgE negativa frente a los componentes de ISAC. Además, se realizó ImmunoCAP frente a Ara h 9, Cor a 8 y Jug r 3 en un subgrupo de pacientes sensibilizados a LTP. La sIgE detectada por ImmunoCAP fue comparada con los rangos de ISAC. Resultados: La mayoría de los alérgicos a cacahuete (66,7%), avellana (80,5%) y nuez (84%) estaba sensibilizados a su LTP. Sin embargo, no se detectó sIgE frente a los componentes de ISAC en el 33,3% de alérgicos a cacahuete, 13,9% de alérgicos a avellana y 13,6% de los alérgicos a nuez. El ImmunoCAP permitió detectar sIgE a Ara h 9 en 61,5%, Cor a 8 en 60% y Jug r 3 en 83,3% de los ISAC negativo. En el subgrupo LTP, ImmunoCAP (94,4%) fue superior a ISAC (72,2%) en la detección de sIgE a Ara h 9 (p<0,05). La sIgE frente a Cor a 8 y Jug r 3 fue detectada de forma similar por ambas técnicas. Conclusiones: La micromatriz ISAC es adecuada para el diagnóstico de alergia a avellana y nuez. La sensibilidad del componente Ara h 9 de ISAC debe ser mejorada