An assessment of the role of intradermal skin testing in the diagnosis of clinically relevant allergy to timothy grass

Nasal allergen provocation test: updated indications and diagnostic accuracy

PURPOSE OF REVIEW

The Nasal Allergen Provocation Test (NAPT) is a valuable diagnostic tool for allergic rhinitis, particularly in cases where conventional tests, such as the skin prick test (SPT) and serum-specific IgE (sIgE), yield inconclusive results. By replicating real-life allergen exposure in a controlled setting, NAPT enables the assessment of allergen-specific nasal reactivity. This article aims to review the current knowledge of NAPT.

RECENT FINDINGS

Recent studies have reinforced NAPT as the gold standard for confirming nasal allergic responses. In the past, test protocols, allergen dosages, and outcome measurements varied widely. However, advancements in allergen standardization, the combination of objective and subjective measurements, and metered nasal allergen application have led to an improved and more reliable test method, with ongoing efforts to establish a universal protocol for clinical testing.

SUMMARY

This review summarizes current knowledge on NAPT, including its clinical applications, indications, methodology, and recent advancements. Additionally, we compare NAPT with SPT and sIgE in terms of diagnostic accuracy. The protocols, allergen types and doses, test methodologies, and outcome measures of these studies were analyzed and compared.

Rhinitis 2020: A practice parameter update

This comprehensive practice parameter for allergic rhinitis (AR) and nonallergic rhinitis (NAR) provides updated guidance on diagnosis, assessment, selection of monotherapy and combination pharmacologic options, and allergen immunotherapy for AR. Newer information about local AR is reviewed. Cough is emphasized as a common symptom in both AR and NAR. Food allergy testing is not recommended in the routine evaluation of rhinitis. Intranasal corticosteroids (INCS) remain the preferred monotherapy for persistent AR, but additional studies support the additive benefit of combination treatment with INCS and intranasal antihistamines in both AR and NAR. Either intranasal antihistamines or INCS may be offered as first-line monotherapy for NAR. Montelukast should only be used for AR if there has been an inadequate response or intolerance to alternative therapies. Depot parenteral corticosteroids are not recommended for treatment of AR due to potential risks. While intranasal decongestants generally should be limited to short-term use to prevent rebound congestion, in limited circumstances, patients receiving regimens that include an INCS may be offered, in addition, an intranasal decongestant for up to 4 weeks. Neither acupuncture nor herbal products have adequate studies to support their use for AR. Oral decongestants should be avoided during the first trimester of pregnancy. Recommendations for use of subcutaneous and sublingual tablet allergen immunotherapy in AR are provided. Algorithms based on a combination of evidence and expert opinion are provided to guide in the selection of pharmacologic options for intermittent and persistent AR and NAR.

Understanding differences in allergen immunotherapy products and practices in North America and Europe

Allergen immunotherapy (AIT) is thought to be clinically effective and safe in treating allergic rhinitis, asthma, and stinging insect allergy in Europe and North America. However, there are intercontinental differences in AIT therapeutic products in terms of their application and regulation. In North America unmodified standardized and nonstandardized aqueous aeroallergen extracts are approved and used almost exclusively for subcutaneous immunotherapy, whereas more product options are available in Europe, including adsorbed allergens, chemically modified allergens, or both. Both liquid extracts and tablets are approved for sublingual immunotherapy in Europe. Nevertheless, within the European Union, there are major differences in AIT products approved and used in individual countries. There are major differences in the clinical approach to subcutaneous immunotherapy in polysensitized patients; in the United States mixed extracts containing multiple aeroallergens are used, whereas European allergists preferably administer separate injections of single allergen sources or homologous groups deemed to be clinically relevant. Moreover, the regulatory approach differs between the European Union and United States. In contrast to the United States, where common allergen standards exist based on biologic activity, no common standards exist in Europe. In terms of development of new investigational products, the United States has followed the European example for phase II and III studies; no formal US Food and Drug Administration guidance has been issued.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Common Allergens Prevalent in and Around Ambala, Haryana: An Intradermal Study among Patients with Asthma and Allergic Rhinitis and Atopic Dermatitis

Objective:

Identification of allergens by intradermal test in patients with asthma, allergic rhinitis, and eczema.

Materials and Methods:

Intradermal test was performed in 100 patients of Ambala over an 8-year period to identify the common allergens. A total of 197 allergens including 50 types of pollen, 19 fungi, 17 insects, 14 types of dust, 6 animal dander, 7 types of fabric and feather and 82 types of foods, dust mite, and parthenium were tested.

Results:

In this study, the major allergens were pollen (51%) followed by foods (28.9%), insects (26.9%), fungus (12.6%), dusts (6.7%). Among pollen allergens, Brassica campestris (8%) was a major allergen followed by Ageratum conyzoides (7%) and Artemisia scoparia (6%) Cannabis sativa, Cynodon dactylon and Maerua arenaria (5%). Among the fungal group, Alternaria tenuis, Aspergillus flavus, Aspergillus fumigates, Candida albicans, Penicillium sp., Rhizopus nigricans (3%), Fusarium solani (2%) were found. In the insect group, mosquito (7%), ant (6%), grasshopper (5%), locust (male), moth, and house fly (4%) were the major allergens. Among the dust allergens, grain dust rice (3%), straw dust, house dust, and grain dust bajra (2%) were found. Among the food allergens, prawn (5%), almonds, Baker's yeast, Bengal gram (3%) and mushroom, mango ripe, rajma, cinnamon, chocolate, beans fresh, and areca nut (2%) were found.

Conclusion:

It can be said that the knowledge may help to create a mapping of allergens in this area and help to treat patients by immunotherapy or avoidance strategy.

Diagnosing environmental allergies: Comparison of skin-prick, intradermal, and serum specific immunoglobulin E testing

Background:

Allergists commonly perform intradermal skin testing (IDST) after negative skin-prick testing (SPT) to comprehensively diagnose environmental allergic sensitization. However, with the availability of modern methods to detect serum-specific immunoglobulin E (ssIgE), it is unclear if ssIgE testing could substitute for IDST.

Objective:

To determine the efficacy of ssIgE testing and IDST when added to SPT in diagnosing environmental allergic sensitizations.

Methods:

SPT, IDST, and ssIgE testing to nine common environmental allergens were analyzed in 75 patients with oculonasal symptoms who presented to our allergy clinics in the Bronx, New York, between January 2014 and May 2015.

Results:

A total of 651 SPT and 499 ssIgE tests were independently performed and revealed 162 (25%) and 127 (25%) sensitizations, respectively. When SPT results were negative, IDST results revealed 108 of 452 additional sensitizations (24%). In contrast, when SPT results were negative, ssIgE test results only revealed 9% additional sensitizations. When both SPT and IDST results were negative, ssIgE testing only detected 3% of additional sensitizations, and ssIgE levels were typically low in these cases (median, 1.25 kU/L; range, 0.357–4.47 kU/L). When both SPT and ssIgE test results were negative, IDST results detected 15% additional sensitizations.

Conclusion:

IDST detected more additional environmental sensitizations compared with ssIgE testing. IDST, therefore, may be useful when the SPT and/or ssIgE testing results were negative, but the exposure history indicated relevant allergic sensitization. Serology added only a little more information if both SPT and IDST results were negative but may be useful in combination with SPT if IDST cannot be performed.

Comparison of Intradermal Dilutional Testing with the Multi-Test II Applicator in Testing for Mold Allergy

OBJECTIVES: To compare and correlate wheal size using the Multi-Test II applicator with the endpoint obtained by intradermal dilutional testing (IDT) for common mold allergens. To validate the safety and efficacy of modified quantitative testing (MQT) for determining immunotherapy starting doses.

STUDY DESIGN AND SETTING: Prospective study of 86 subjects with Multi-Test II and IDT for 6 common mold antigens.

RESULTS: There was 84% concordance between IDT results and the results expected from the MQT method. When IDT and MQT results differed, the MQT algorithm predicted a safer end-point for starting immunotherapy in all but 2 cases.

CONCLUSION: The correlation between Multi-Test II and IDT is not strong enough to infer IDT endpoint from Multi-Test II results for molds. MQT is nearly as effective as formal IDT in determining endpoint.

SIGNIFICANCE: MQT appears to be a safe method for determining starting doses for immunotherapy with fungal allergens.

Nonallergic Rhinitis: Diagnosis

Nonallergic rhinitis (NAR) is one of the most common conditions in medicine, affecting the quality of life of millions of patients throughout the United States. Despite its ubiquitous nature, NAR remains a poorly managed and often difficult to treat condition. NAR is often suboptimally managed by clinicians with poor clinical outcomes. Establishing the correct diagnosis requires a keen understanding of the unique underlying mechanisms involved in NAR, which is still evolving. Ultimately epidemiologic studies that better define NAR prevalence and its economic burden on society are needed to convince funding agencies of the need for research to elucidate mechanisms and specific treatment approaches for this condition.

Clinical Evaluation and Management of Patients with Suspected Fungus Sensitivity

Fungus-sensitized patients usually present with symptoms that are similar to symptoms presented by those who are sensitized to other aeroallergens. Therefore, diagnosis and management should follow the same pathways used for patients with allergic conditions in general. The physician should consider that a relationship between fungal exposure and symptoms is not necessarily caused by an IgE-mediated mechanism, even when specific fungal IgE is detected. Until recently, IgE-mediated allergy has been documented only for a limited number of fungi. We propose a series of questions to be used to identify symptoms that occur in situations with high fungal exposure and a limited skin-prick-test panel (Alternaria, Cladosporium, Penicillium, Aspergillus, Candida) that can be amplified only in cases of high suspicion of other fungal exposure (eg, postfloods). We also review in vitro testing for fungi-specific IgE. Treatment includes environmental control, medical management, and, when appropriate, specific immunotherapy. Low-quality evidence exists supporting the use of subcutaneous immunotherapy for Alternaria to treat allergic rhinitis and asthma, and very low quality evidence supports the use of subcutaneous immunotherapy for Cladosporium and sublingual immunotherapy for Alternaria. As is the case for many allergens, evidence for immunotherapy with other fungal extracts is lacking. The so-called toxic mold syndrome is also briefly discussed.

Skin testing versus serum-specific IgE testing: which is better for diagnosing aeroallergen sensitization and predicting clinical allergy?

An accurate diagnosis of aeroallergen sensitization is pivotal to clinical practice and research. Given the recent technological advances in analyzing serum allergen-specific IgE, the question of which testing method, skin or serum testing, is superior in diagnosing allergic sensitization must be readdressed, as well as their value in predicting clinical disease. This review article provides a detailed summary of recent studies addressing these questions. Conclusively, most studies show substantial discordance between serum-specific IgE and skin testing results, suggesting that the two testing methods compliment each other and cannot be used interchangeably. On average, using only one testing method may misdiagnose every fourth allergically sensitized patient as non-sensitized. In addition, depending on the allergen tested, skin prick testing and serum-specific IgE testing appear to be the methods of choice in predicting outcomes of experimental allergen challenge, while intradermal testing is less contributory.

Chitin microneedles for an easy-to-use tuberculosis skin test

An easy-to-use tuberculosis skin test is developed with chitin microneedles that deliver purified protein derivative at the correct skin depth and result in a positive test in BCG-immunized guinea pigs.

Allergen immunotherapy extract treatment set preparation: making a safer and higher quality product for patients

The best possible allergen immunotherapy clinical outcomes require the provision of high quality and safe allergen immunotherapy extract preparations. Evolving national guidelines and regulatory bodies have devoted special attention to the safe compounding of sterile products, including allergen extracts. It is incumbent upon allergists preparing extract treatment sets for patients to be familiar with and adopt training, procedures and safety measures that lead to standardized high quality products. Preparers and supervisors must maintain ongoing competency in aseptic technique and prescribing principles, such as probable effective dose ranges, allergen cross-reactivity, and separation of high protease-containing extracts from susceptible extracts. Accordingly, knowledge and application of vial labeling, diluent selection, standard operating procedures, mixing log documentation, and mixing condition principles are a necessity. Although there have been no instances of infectious complications from allergen immunotherapy in a century of clinical practice, continued vigilance in the use of measures that ensure extract sterility is paramount. A review of allergen immunotherapy preparation recommendations and best practices based on published national guidelines is presented. Further study of preparation measures and prescribing principles will continue to advance the practice of allergen immunotherapy and offer opportunities for refinement of current recommendations.

World allergy organization study on aerobiology for creating first pollen and mold calendar with clinical significance in islamabad, pakistan;: a project of world allergy organization and pakistan allergy, asthma & clinical immunology centre of islamabad

Pollen and mold allergies are highly problematic in Islamabad. This study was conducted to investigate the type and concentration of airborne pollens/molds causing allergic diseases in susceptible individuals. A volumetric spore trap (Burkard) was placed at the height of 11 m and ran continuously for 3 years. Once a week, the collecting drum was prepared by affixing Melinex tape with a double sided adhesive that was coated with a thin layer of silicone grease. Every Sunday at 9:00 AM the drum was replaced by another drum and the pollen/mold spores were removed and permanently mounted on slides. Using a microscope, the trapped particles were identified and recorded as counts per cubic meter of air per hour. From these data, the pollen and mold calendars were constructed and expressed as counts per cubic meter of air per day. Skin prick tests were performed on more than 1000 patients attending the Pakistan Allergy, Asthma & Clinical Immunology Centre of Islamabad. The results indicated that there were 2 main pollen plants that contributed to seasonal allergies. These were Broussonetia papyrifera and Cannabis sativa during the March/April season and the July/September season, respectively. Although mold spores were continuously detected throughout the year, the most prominent mold was undetected mold and unconfirmed mold species similar to Stachybotrys species, which was high from July to September/October. Two additional molds contributing to allergic reactions were Pithomyces species and Cladosporium species, which were active during January and April, with the latter also being detected between October and November. These results may prove beneficial to both patients and physicians in planning a therapeutic protocol for avoidance and amelioration.

Allergic rhinitis

Familiarity with the diagnosis and management of allergic rhinitis is important for physicians concerned with the nasal airway. Allergic rhinitis is a common and manageable condition that may cause persistent or intermittent symptoms that vary as to duration and severity. Allergic rhinitis impairs quality of life, sleep, school performance, and productivity on a scale that compares with other chronic diseases. Diagnosis is primarily clinical, but supported by allergy testing. Therapeutic options for allergic rhinitis include pharmacotherapy, environmental control, and immunotherapy. More recently, a role for sublingual immunotherapy and turbinate reduction has been reported.

Intradermal skin test results correlate with atopy

Intradermal skin testing (IDST) is performed by most allergists, but its value remains controversial. In most previous studies assessing the value of IDST, a positive result was based on a 5- to 6-mm wheal and erythema. While a subject's immediate reaction upon allergen exposure is a common endpoint to determine "allergy," additional known allergic phenomena such as the delayed or late-phase response to allergen exposure suggest that correlation only with current history or acute challenge may result in an incorrect labeling of false-positive results when, in fact, there is a physiologic response to exposure, albeit a reaction not immediately evident. We conducted a retrospective study to determine if positive IDST reactions represent nonspecific irritation or if they correlate with atopy. We retrospectively reviewed the records of 100 patients who had undergone skin prick testing (SPT) and IDST and compiled data on their age, sex, diagnosis, and number of skin and intradermal reactions. Results were analyzed according to a general linear model to see if the development of a positive IDST result correlated with atopy (defined as SPT positivity). We found statistically significant differences between SPT-positive and -negative patients with regard to diagnoses of asthma, rhinitis, or both (p=0.008). Controlling for asthma and rhinitis, we also found a significant association between atopy and a positive IDST result; among atopic (SPT+) patients, a mean of 25.9% of IDST results were positive, compared with a rate of only 6.7% IDST positivity among the nonatopic (SPT-) patients (p<0.0001). We conclude that IDST is more commonly positive in atopic (SPT+) than nonatopic (SPT-) patients, suggesting that a positive IDST represents genuine atopy and bona fide sensitization rather than nonspecific irritation.

The History of IgE: From discovery to 2010

The discovery of IgE and the role of IgE-mediated inflammation gave clinical allergy a scientific backbone, and as a result, the reputation of the specialty allergy has increased considerably over the years. Allergy diagnosis was improved by assays for in vitro determination of the presence and concentration of IgE antibodies, and clinical knowledge also broadened, allowing better service for the increasing number of allergic individuals. Access to immune assays for allergens finally allowed characterization and standardization of allergen preparations used for diagnosis and allergen-specific immunotherapy. Improved basic molecular technologies have further increased our knowledge about the complex component composition of an allergen extract, introduced IgE-specific immunotherapy, and allowed the allergist to better handle even severe allergic reactions such as anaphylaxis.

Allergic rhinitis with negative skin tests

Recently, several studies have revealed a subset of patients who have positive nasal provocation to allergens despite having a negative skin prick test. It has been hypothesized that these patients have localized allergic rhinitis. However, the prevalence varies greatly, ranging from 0% to 100% of skin test-negative individuals. This wide range in prevalence is likely related to differences in methodology, including differences in allergen manufacturers, concentrations, and numbers of allergens tested and, perhaps most importantly, criteria for a positive nasal challenge. Despite the evidence to date, many challenges exist with regard to the concept of localized nasal allergy. Further studies will be required to further define the immunopathology, prevalence, practical diagnostic tests, and management.

Analysis of allergen specific IgE cut points to cat and dog in the Childhood Allergy Study

BACKGROUND

The application of a single allergen specific IgE (sIgE) cut point, such as 0.35 kU/L, to determine sensitization for all allergens may be suboptimal.

OBJECTIVES

To analyze self-reported symptoms suggestive of dog and cat allergy in relation to the test performance characteristics of low level, but reliably detectable, sIgE and to compare these cut points to the traditional 0.35-kU/L cut point.

METHODS

Interviews and blood samples were collected among 564 young adult participants of a general risk birth cohort. Data collected from the participants' parents were analyzed as validation populations. A history of symptoms consistent with allergy on exposure to pets was obtained by standardized questionnaire. Allergen sIgE levels for dog and cat were evaluated with Pharmacia CAP. Receiver operating characteristic curves were constructed and the performance characteristics of the traditional sIgE cut point of 0.35 kU/L were compared with cut points as low as 0.1 kU/L.

RESULTS

Using the Youden J criteria, based on the highest sum of sensitivity and specificity for a diagnostic test, cut points of 0.12 kU/L for cat and 0.2 kU/L for dog were identified as performing optimally among the participant population. In 2 validation populations, consisting of the participants' mothers and fathers, the performance of these alternative cut points were superior or similar to the traditional 0.35-kU/L sIgE level.

CONCLUSIONS

Accurately measured sIgE at levels approaching the lower limit of detection of current assays may be useful in confirming sensitization. Optimal clinical application of these tests will continue to require careful integration of the result and the strength of the patient's history.

A review of allergen-specific immunotherapy in human and veterinary medicine

This article reviews allergen-specific immunotherapy in human and veterinary medicine. Current hypotheses of possible mechanisms of actions are outlined. Indications, success rates, adverse effects and factors influencing outcome of therapy are discussed in humans, dogs, cats and horses.

Pearls and pitfalls of allergy diagnostic testing: report from the American College of Allergy, Asthma and Immunology/American Academy of Allergy, Asthma and Immunology Specific IgE Test Task Force

The intended purpose of this monograph is to provide a general overview of allergy diagnostics for health care professionals who care for patients with allergic disease. For a more comprehensive review of allergy diagnostic testing, readers can refer to the Allergy Diagnostic Practice Parameters. A key message is that a positive allergy test result (skin or blood) indicates only the presence of allergen specific IgE (called sensitization). It does not necessarily mean clinical allergy (ie, allergic symptoms with exposure). It is important for this reason that the allergy evaluation be based on the patient's history and directed by a health care professional with sufficient understanding of allergy diagnostic testing to use the information obtained from his/her evaluation of the patient to determine (1) what allergy diagnostic tests to order, (2) how to interpret the allergy diagnostic test results, and (3) how to use the information obtained from the allergy evaluation to develop an appropriate therapeutic treatment plan.

The role of intradermal skin testing in inhalant allergy

OBJECTIVE

To provide an overview of the role of intradermal skin testing (IDST) in inhalant allergy.

DATA SOURCES

A literature search was conducted in MEDLINE to identify peer-reviewed articles related to IDST using the following keywords: skin testing, intradermal, intracutaneous, aeroallergen, and inhalant allergen. In addition, references cited within these articles were also reviewed.

STUDY SELECTION

Articles were selected based on their relevance to the topic.

RESULTS

The use of IDST for inhalant allergy varies widely among allergists. When performed, it is necessary to use a 100- to 1,000-fold dilution from the stock allergen extract. IDST is used routinely in the standardization of extracts in the United States. With a negative skin prick test result, a positive IDST result has low agreement with in vitro and challenge results and generally adds little to the diagnostic evaluation. In contrast, a negative IDST result generally has a high negative predictive value. Only a few inhalant allergens have been evaluated with challenge models for IDST. A summary of the data is also presented in tabular form.

CONCLUSIONS

Most of the literature suggests that with a negative skin prick test result, a positive IDST result adds little to the diagnostic evaluation of inhalant allergy. However, additional studies are necessary using challenge models for less potent and nonstandardized inhalant allergens (molds, trees, dog, weeds).

Multiallergen nasal challenges in nonallergic rhinitis

BACKGROUND

It has been proposed that some patients with nonallergic rhinitis may have "localized allergy" of the nasal mucosa. Nasal challenges with aeroallergens can help determine whether a patient is clinically allergic via an IgE-mediated pathway.

OBJECTIVE

To determine the prevalence of localized allergy in patients with negative skin prick test results via nasal challenges with an array of allergens.

METHODS

Twenty individuals with perennial rhinitis and negative epicutaneous test results to common perennial aeroallergens underwent nasal challenges to glycerin, Alternaria, cockroach, timothy grass, cat hair, and Dermatophagoides pteronyssinus. Total symptom scores, peak nasal inspiratory flow rates, and nasal eosinophil counts were determined.

RESULTS

Of 20 patients with nonallergic rhinitis, 4 were hyperresponsive to glycerin and were not subsequently challenged. Eleven patients had negative nasal challenges. Five patients developed positive challenges (total symptom score > or = 5) to 7 allergens. These 5 patients returned for nasal provocation testing to their offending allergens, and these repeated challenges were negative. Three control subjects with allergic rhinitis developed positive challenges after nasal allergen challenge.

CONCLUSIONS

Although some individuals with nonallergic rhinitis can have positive nasal allergen challenges, these results were not reproducible in the present patient population.

Evidence-based recommendations regarding the differential diagnosis and assessment of nasal congestion: using the new GRADE system

Nasal congestion is an important symptom in nasal pathology and can be defined as an objective restriction of nasal cavity airflow because of mucosal pathology and/or increased mucus secretion (excluding anatomical variants). Using the new Grading Recommendations Assessment, Development and Evaluation system, evidence-based recommendations are made that will encompass different clinical questions regarding diagnostic modalities of nasal congestion: (i) their usefulness in assessment of presence and severity of congestion; (ii) their usefulness in assessment of etiological pathology responsible for congestion; and (iii) their usefulness in follow up and treatment effectiveness evaluation of nasal congestion.

Allergic rhinitis--current approaches to skin and in vitro testing

This article discusses the currently available techniques used for the diagnosis of IgE-mediated upper respiratory allergy. These methods are necessary to confirm the presence and the intensity of allergy in an effort to select patients for immunotherapy and to dose immunotherapy properly. Specific techniques discussed include epicutaneous and intradermal skin tests and in vitro tests designed to measure antigen-specific IgE antibody.

Evidence-based allergy diagnostic tests

Effective management of allergic diseases relies on the ability to make an accurate diagnosis. Although clinicians rely on experience obtained over many years of practice, such experience is anecdotal and unique to the individual using it. The result is a tendency for patients with similar clinical presentations to receive different diagnoses and treatment, depending on which provider they happened to see. The probability that a patient has a particular diagnosis can be determined using a combination of diagnostic tests. To make the best use of tests, it is important to understand their performance characteristics in terms of reproducibility and likelihood ratios. A test that is reproducible but that does not predict the presence of a disease is not helpful, nor is an accurate test that is not reproducible. To improve the reproducibility of diagnostic tests, it is important that proficiency testing be instituted for both skin and in vitro tests so that the coefficient of variance can be determined. This has already been done for the latter and needs to be done for skin tests as well. With use of a combination of history and appropriate diagnostic tests, the probability that a particular diagnosis is present can be increased or decreased sufficiently either to confirm it or to rule it out. As proficiency testing of allergy tests becomes more common and the use of tests becomes more consistent, we believe that patients with allergic diseases will benefit.

Use of intradermal dilutional testing and skin prick testing: clinical relevance and cost efficiency

OBJECTIVES/HYPOTHESIS

The objective was to determine the agreement of the positive results from a multiple skin prick test (SPT) device with the ability to determine a definable endpoint through intradermal dilutional testing (IDT) to compare semiquantitatively the degree of positivity of SPT results with quantitative results from IDT and to analyze the cost of immunotherapy based on SPT compared with IDT guided by SPT.

STUDY DESIGN

Retrospective review of clinical data (random accrual).

METHODS

One hundred thirty-four patients underwent allergy screening using a multiple SPT device. Antigens testing positive by skin prick device were tested using IDT on a separate day. Antigens testing negative by SPT were not evaluated by IDT. Regional allergy testing practice patterns were determined, and a cost analysis using Medicare rates was performed

RESULTS

There was good agreement between an antigen testing positive by SPT and the determination of a definable endpoint (93.33%, n = 1,334 antigens). The degree of positivity from the SPT correlated poorly with the final endpoint concentration (r = 0.40, P < .0001). Blended testing techniques were similar in cost when compared with several commonly used allergy testing protocols.

CONCLUSIONS

Antigens which show reactivity to a multiple SPT device usually have a treatable endpoint that is independent of the degree of positivity of the SPT result. IDT is an important step in the determination of the strongest starting dose of immunotherapy that may be safely administered. Initiating immunotherapy in this manner may potentially create significant health care savings by shortening the time required for a patient to reach their individual maximally tolerated dose. The use of a relatively large screening panel is cost effective and does not increase the average number of antigens treated by immunotherapy. Blended allergy testing techniques that include IDT in their protocol are comparable in cost with commonly used allergy testing protocols.

Intradermal positivity after negative prick testing for inhalants

OBJECTIVE

Examine the incidence of positive intradermal tests after a negative skin prick test for 24 inhalant antigens.

STUDY DESIGN AND SETTING

Retrospective study. Charts from patients who underwent modified quantitative testing (MQT) over a 3-year period were reviewed. Patients were initially tested with Multi-Test II. Subjects with negative wheals to a specific allergen were then tested with a 1:500 weight:volume intradermal injection of that allergen.

RESULTS

One hundred thirty-three patients underwent MQT for 24 antigens. Allergens with the highest incidence of positive intradermal wheals after negative prick testing were Dermatophagoides pteronyssinus and Dermatophagoides farinae at 26.67%. Allergens with elevated incidence of positive intradermals included fusarium, cockroach, cocklebur, rough marsh elder, and ragweed, all with incidences of 16% to 19%.

CONCLUSION

Positive intradermal responses after negative prick testing occur commonly. Future study is needed to determine the generalizability and clinical significance of these findings.

EBM RATING

C-4.

Allergy skin test responses during experimental infection with respiratory syncytial virus

BACKGROUND

Allergy skin testing is one of the most frequently performed physician office procedures. Many factors can affect the results of those tests, including the well-defined suppressive effect of systemic antihistamines. False-positive allergen skin test results are known to occur; however, contributing factors are not well understood.

OBJECTIVE

To determine whether a viral upper respiratory tract infection affects allergy skin test responsiveness.

METHODS

We performed skin tests with histamine and a panel of geographically relevant inhalant allergens on 16 adults before and 3, 6, and 21 days after experimental exposure to respiratory syncytial virus (RSV), a virus that causes signs and symptoms of a cold.

RESULTS

The RSV exposure, with and without documented infection, caused increased wheal and flare areas to histamine and allergen and de novo positive allergen test responses in individuals with no measurable responses at baseline. These were noted as late as 21 days after RSV exposure and may be consistent with mediation by up-regulated neurogenic inflammation during RSV infection.

CONCLUSION

These results may have implications for explaining the cause of such well-known complications of RSV infection as otitis media, bronchiolitis, and asthmatic exacerbation.

Skin testing

OBJECTIVE

To provide the reader with a relevant review of the literature regarding skin testing in the allergist's office.

DATA SOURCES

A PubMed search for the years 1970 through 2005 was performed using the following keywords: allergy skin testing, skin prick testing, and intradermal skin testing.

STUDY SELECTION

Articles that highlighted aspects of sentinel to clinical allergists' use of skin testing in the office, such as methods of skin testing, intradermal vs skin prick testing, skin test devices, and methods of expressing skin test results, were selected for further review.

RESULTS

Skin testing remains the central test to confirm an allergic response. It is minimally invasive and when performed correctly has good reproducibility. Results are easily quantifiable and correlate well with end organ challenge. It is imperative however that technicians who perform the skin tests and the clinicians who order or interpret these tests understand the characteristics of the specific tests they are administering. It is also important that the clinician express skin test results in a manner that allows easy interpretation by another physician.

CONCLUSIONS

Allergists must consider controllable variables that affect skin test results and their interpretation. When not considered, they may be responsible for some of the inaccuracies associated with allergy skin testing.

Skin testing: a survey of allergists

BACKGROUND

In the allergist's office, skin testing remains the central way to confirm allergic response. Although anecdotal data suggest widely varying practices in skin testing by allergists, the diversity and relative frequency of these practices have not been documented.

OBJECTIVE

To determine the extent of the diversity in skin testing practices among allergists.

METHODS

A questionnaire was sent via the Internet to all physician members and fellows of the American College of Allergy, Asthma and Immunology who practice in the United States. This survey explored choice of extract concentrations, skin test device, number and type of tests, method for interpretation and documentation of skin test results, and quality assurance procedures used.

RESULTS

Overall, a significant degree of variability was reported with regard to number of skin tests performed, extract concentrations, skin test devices, interpretation and documentation of results, and quality assurance procedures. The average number of skin prick tests performed ranged from 5.09 (grasses) to 10.9 (trees), whereas the average number of intradermal tests performed ranged from 2.03 (grasses) to 5.6 (perennial). The allergen extract concentrations used for intradermal testing varied widely. Expressed as a dilution of the concentrated extracts, 20.8% use 1:100 dilutions, 10.3% use 1:500 dilutions, and 59.4% use 1:1,000 dilutions. Significant variability also occurred regarding devices and the technique with which the devices were used. Most clinicians (92.1%) used the most concentrated extract available for skin prick testing. For reporting the results of skin testing, 53.8% used a 0 to 4+ scale, and only 28.3% measured orthogonal diameters. Of those using a 0 to 4+ scale, two thirds related the results to the size of the histamine control. Quality assurance testing was reportedly performed by 61.2% of responders. However, less than 10% of responders used an objective test protocol for this purpose.

CONCLUSIONS

This survey highlights some of the areas that allergists can improve on in the use and reporting of skin tests.

Influence of patient care provider on patient health outcomes in allergic rhinitis

BACKGROUND

Diagnosing and managing the symptoms of allergic rhinitis are largely the responsibility of family physicians and allergists, but some patients choose self-management. However, few data are available to determine how the choice of care relates to measures of patient outcomes, such as the ability to perform activities, quality of life, and productivity.

OBJECTIVE

To examine and compare patients' ability to perform activities, quality of life, productivity, and symptoms according to care provider: family physician, allergist, or self-management.

METHODS

A questionnaire was developed and mailed to 2,065 patients enrolled in a 500,000-member managed care organization. Patients were identified by diagnostic codes for allergic rhinitis as determined from a retrospective examination of medical and prescription claims records between January 1, 2000, and December 31, 2000.

RESULTS

Chi-squared Tests revealed statistically significant differences for symptoms, family history, testing, immunotherapy, and test value among patient care providers. Multivariate analysis of variance revealed statistically significant differences for activities, symptoms, and quality of life among patient care providers. Findings support the use of diagnostic testing to improve patient outcomes. Symptoms were statistically significantly associated with measures of productivity.

CONCLUSIONS

Patient outcomes vary with respect to patient care group. It is imperative that patients suspected of having allergic rhinitis undergo appropriate evaluation and testing. Outcomes can be optimized if allergists and family physicians have access to appropriate diagnostic tools, such as skin testing and serologic tests for specific IgE antibodies.

Role of intradermal skin tests in the evaluation of clinically relevant respiratory allergy assessed using patient history and nasal challenges

BACKGROUND

Skin testing, correlated with patient history, is the accepted method of identifying clinically relevant aeroallergen sensitivity. Traditionally, intradermal tests are believed to be more sensitive in identifying aeroallergen sensitivity than the epicutaneous and percutaneous methods. Therefore, many allergy practitioners use the epicutaneous or percutaneous method first and, if the results are negative, follow up with intradermal tests.

OBJECTIVES

To compare the epicutaneous, percutaneous, and intradermal methods to determine their sensitivity to patient history and to evaluate the value of intradermal tests when epicutaneous and percutaneous test results are negative.

METHODS

Participants were evaluated for rhinoconjunctivitis symptoms and then were skin tested using the prick and Multi-Test II (MTII) methods. Intradermal tests were performed when prick and MTII test results were negative to an aeroallergen. Participants with negative prick and MTII test results and corresponding positive intradermal test results underwent nasal challenges with evaluation by anterior rhinomanometry.

RESULTS

Compared with patient history, average sensitivity for MTII was 77% and for the prick method was 62%. When MTII results were negative, 17% of intradermal tests corresponded with probable patient histories of allergy but none with positive nasal challenge results. Nasal challenge results were similar to those of the negative control group and significantly different from those of the positive control group (P < .001).

CONCLUSIONS

The MTII tests are more sensitive and equally specific compared with the prick method. When MTII results are negative, positive intradermal test results are unlikely to identify clinically relevant aeroallergen sensitivity. Routine performance of intradermal tests when MTII results are negative is likely to be of low clinical yield.

Evidence-based strategies for treatment of allergic rhinitis

In this review, an evidence-based medicine approach to diagnosis and treatment for allergic rhinitis is reviewed. We performed a search of the medical literature for randomized, placebo-controlled trials of nonsedating antihistamines, intranasal corticosteroids, montelukast, azelastine, allergen immunotherapy, and anti-IgE. The mean numbers needed to treat were: nonsedating antihistamines--15.2; nasal corticosteroids--4.4; montelukast--14.3; azelastine--5.0; allergen immunotherapy--4.6; and anti-IgE--12.4. Treatment thresholds for use were: antihistamines--23%; nasal corticosteroids--8%; azelastine--16%; montelukast--8%; anti-IgE--50%; and immunotherapy--25%. When used appropriately, this information could become very useful for clinicians, particularly if cost, convenience, and other indirect factors can be included.

Usefulness of specific IgE antibody tests: a progress report

LEARNING OBJECTIVES

To enable the readers to recognize some of the history, problems, progress, interpretation, and present status of assays for specific IgE (s-IgE) antibodies.

DATA SOURCES

Peer-reviewed literature in the field.

STUDY SELECTION

Key articles were selected by the author.

RESULTS

Clinical and analytical studies have differed widely in their conclusions as to the performance of tests for s-IgE. Study conclusions depend on the testing method used, the allergen(s) studied, patient selection, and, most importantly, the standards used for comparison. Today, only a handful of the once commercially developed assays still exist, and some of these still do not compare well to an analytical ideal standard. However, with the extent of regulation and economic pressures, most of the surviving s-IgE tests are considerably improved over what had existed before them.

CONCLUSIONS

Allergic diseases with multiple symptom patterns seem to be increasing in modern societies. Objective methods are needed to differentiate allergic origins from other mechanisms that cause similar symptoms. Accurate, quantitative, and objective methods for s-IgE measurement are now available and can be used effectively in clarifying allergic diagnoses when interpreted in conjunction with the clinical history.

A Comparison of Skin Endpoint Titration and Skin-Prick Testing in the Diagnosis of Allergic Rhinitis

Among the many methods of allergy diagnosis are intradermal testing (IDT) and skin-prick testing (SPT). The usefulness of IDT has been called into question by some authors, while others believe that studies demonstrating that SPT was superior might have been subject to bias. We conducted a study to compare the validity of SPT and IDT—specifically, the skin endpoint titration (SET) type of IDT—in diagnosing allergic rhinitis. We performed nasal provocation testing on 62 patients to establish an unbiased screening criterion for study entry. Acoustic rhinometric measurements of the nasal responses revealed that 34 patients tested positive and 28 negative. All patients were subsequently tested by SET and SPT. We found that SPT was more sensitive (85.3 vs 79.4%) and more specific (78.6 vs 67.9%) than SET as a screening procedure. The positive predictive value of SPT was greater than that of SET (82.9 vs 75.0%), as was the negative predictive value (81.5 vs 73.0%). None of these differences was statistically significant; because of the relatively small sample size, our study was powered to show only equivalency. The results of our study suggest that the information obtained by the SET method of IDT is comparable to that obtained by SPT in terms of sensitivity, specificity, and overall performance and that both SET and SPT correlate well with nasal provocation testing for ragweed. Therefore, the decision as to which to use can be based on other factors, such as the practitioner's training, the desire for quantitative results, the desire for rapid results, and the type of treatment (i.e., immunotherapy or pharmacotherapy) that is likely to be chosen on the basis of test results.

Are our impressions of allergy test performances correct?

BACKGROUND

The clinical diagnosis is often subjective and susceptible to bias, yet it is the primary standard by which diagnostic tests are judged. Consequently, our opinions regarding various diagnostic tests may not be entirely accurate.

OBJECTIVE

To investigate the accuracy of the clinical history compared with concordant skin and quantitative specific IgE (s-IgE) measurements.

METHODS

Consecutive, consenting patients (N = 152) at 2 different allergy centers were examined by history and physical examination (HPE) alone to determine their sensitivity to 7 common allergens. Results were classified as positive, negative, or indeterminate. The HPE results were then compared to concordant skin prick testing (SPT) and s-IgE measurements and to quantitative IgE antibody measurements with and without knowledge of the SPT results.

RESULTS

Diagnosis by HPE deviated considerably from concordant SPT and s-IgE results. This deviation differed between allergists and allergens, reflecting a positive HPE bias that averaged 22%. Seventy-six percent of the HPE results judged indeterminate were resolved as negative. Using additional information from the quantification of s-IgE antibodies, considerable differences between the sites in the level of s-IgE associated with a positive HPE result with and without SPT results were observed.

CONCLUSIONS

Relative to the SPT and quantification of s-IgE antibodies, the diagnosis by HPE alone to common allergens is not consistent. Discrepancies were dependent on both allergen and allergist. The quantitative s-IgE data revealed that allergists use available information from the HPE and SPT differently. Since the HPE is the primary standard used in judging test efficacy (sensitivity and specificity), our current impressions of test performances are not likely to be accurate.