Skin prick tests and allergy diagnosis

Abstract

Skin testing remains an essential diagnostic tool in modern allergy practice. A signifi cant variability has been reported regarding technical procedures, interpretation of results and documentation. This review has the aim of consolidating methodological recommendations through a critical analysis on past and recent data. This will allow a better understanding on skin prick test (SPT) history; technique; (contra-) indications; interpretation of results; diagnostic pitfalls; adverse reactions; and variability factors. Skin has an important physiological role in the internal balance homeostasis and constitutes a crucial barrier against external aggressions, with well-known immunological properties. 1 It has been used by allergists for decades as an easily assessed laboratory of the immunological status of the individual.The fi rst skin testing technique was developed by Charles H. Blackley in 1865, a Manchester homeopathic physician with allergic rhinitis. He abraded a quarter-inch area of his skin with a lancet and then applied grass pollen grains. 2 The so-called scratch test was later adopted by Schloss for the diagnosis of food allergy in children. 3 Epicutaneous tests can be divided into scratch tests and prick/puncture tests. The fi rst method, proposed by Blackley 2 , implied a linear scratch without drawing blood and could either be performed fi rst, with the extract then dropped on the abraded skin, or be made through a drop of extract. 4 Although it was used extensively in the past, this technique became progressively obsolete due to patient discomfort, poor reproducibility, possible residual lesions and newer and innocuous procedures. 4 Therefore, scratch test is mentioned here for historical purposes only. It was Sir Thomas Lewis who, in 1924, fi rst applied skin prick tests (SPT). 5 Nevertheless, their generalised use in clinical practice only became a reality about 30 years ago, as a result of technique modifi cations proposed by Pepys. 6 For the purpose of this review and for easier comprehension, skin testing will be referred interchangeably as SPT, whatever device is used for its application.In 1966, Ishizaka's work on immunoglobulin E (IgE) and immediate hypersensitivity reactions 7 established the scientifi c corpus to what was done till then on a strictly empiric basis.As written by Dr Walzer in 1974, "the fact that skin testing has not turned out to be a simple and completely reliable technique does not detract from the fact that, when it is intelligently and skilfully performed, it remains the most effective diagnostic procedure in reaginic allergic disorders". 8 The reliability of skin testing and proper documentation of test results are essential in allergy practice. A recent survey to all physician members and fellows of the American College of Allergy, Asthma and Immunology practicing in the

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“…The prick-to-prick method is often used in such circumstances and involves placing the end of the needle into the material and then pricking the patient's skin with this needle. However, this approach is known to administer variable levels of unstandardized test material, thus leading to false positive results as well as the potential for adverse reactions (Antunes et al, 2009). To this point, the food allergy sensitivity rate (i.e., the rate of true positive outcomes) for the skin prick test has been estimated to be approximately 85%, indicating a false positive test in one-to-two subjects for every ten subjects tested (reviewed in Kurowski and Boxer, 2008).…”

Serum levels of IL-10, IL-17F and IL-33 in patients with asthma: a case–control study

“…In skin prick test (SPT), sensitization to a total of 35 allergens (HollisterStier Allergy, USA) was assessed in which the wheal size greater than 3mm of saline control was considered as positive [26]. Severity of sensitization was characterized by comparing the largest wheal diameter measured for an allergen with that of histamine.…”

Diagnosis and treatment of allergic diseases in Zhejiang Province: A cross-sectional survey

“…SPT is an in vivo test to assay the immediate IgE response to specific allergens, which reflects the function of mast cells that react to allergens (Li, 2002). It is cheap and convenient, easy to operate, and is stated to be the preferred technique for IgE-mediated hypersensitivity by the Practice Parameter from 2008 (Bernstein et al, 2008), though training is needed for those who gather and interpret the results (Antunes et al, 2009;Bousquet et al, 2012). As an in vitro test, the ssIgE test is safer, without the influence of drugs and personal subjective bias (Siles and Hsieh, 2011).…”