Evidence-based allergy diagnostic tests

Abstract

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.

Skin prick/puncture testing in North America: a call for standards and consistency

“…It is minimally invasive and allows for the evaluation of multiple allergens in a single session [16, 17]. When performed correctly, skin prick tests are a relatively safe and efficient way to reproducibly diagnose clinical allergy [16–18]. It is a method that is comparatively inexpensive to perform, with results available in 15 to 20 minutes [19], and the test itself evaluates sensitivity based directly on the actual agent of interest [18].…”

“…When performed correctly, skin prick tests are a relatively safe and efficient way to reproducibly diagnose clinical allergy [16–18]. It is a method that is comparatively inexpensive to perform, with results available in 15 to 20 minutes [19], and the test itself evaluates sensitivity based directly on the actual agent of interest [18]. The objective evidence available in the literature supporting the sensitivity, specificity, and positive and negative predictive values of SPT confirms its clinical utility [8].…”

“…The need for tester proficiency has been demonstrated in a study in which 4 experienced nurses were tasked with performing SPT for grass, dust mite, dog, and mugwort with histamine and saline controls on the same individuals [18]. The target coefficient of variation (CV) between individual nurses was 25% or less [18].…”

“…The target coefficient of variation (CV) between individual nurses was 25% or less [18]. Resulting CVs ranged from 55.9% for saline negative controls to 16.6% for histamine-positive controls.…”

Allergen microbead arrays: the future of allergy diagnostics?

“…At the moment, investigative work is widely performed by means of diagnostic reagents, directly derived from the biological sources responsible for allergic sensitization. These allergenic extracts are utilized both for cutaneous and in vitro IgE testing [3,4]. Unfortunately, a series of pitfalls actually impair the consistency of diagnostic tools based on extract: these reagents, in fact, provide no information on the specific culprit protein(s) responsible for IgE sensitization, it is impossible to distinguish panallergens' IgE reactivity from a genuine antigen recognition, and contaminants or genuine but irrelevant components could prejudice a precise evaluation, both diluting or giving the possibility for a false IgE reactivity [5].…”