Short Communication

The Longest Wheal Diameter Is the Optimal Measurement for the Evaluation of Skin Prick Tests
George N. Konstantinou^{a, b}, Philippe-Jean Bousquet^c, Torsten Zuberbier^d, Nikolaos G. Papadopoulos<sup>a

a</sup>Department of Allergy and Allergy Research Center, Pediatric Hospital P&A Kiriakou'', National and Kapodistrian University of Athens, member of the GA²LEN network, and
^bDepartment of Allergy and Clinical Immunology, 417 NIMTS Army Hospital, Athens, Greece;
^cExploration des Allergies, Service des Maladies Respiratoires, Hôpital Arnaud de Villeneuve, Montpellier, France;
^dDepartment of Dermatology and Allergy, Allergie-Centrum-Charité, Charité-Universitätsmedizin Berlin, member of the GA²LEN network, Berlin, Germany

Address of Corresponding Author

Int Arch Allergy Immunol 2010;151:343-345 (DOI: 10.1159/000250443)

  Key Words

• Wheal and flare reactions
• Skin prick test
• Wheal diameter

  Abstract

Background: Mean diameter or longest diameter are the 2 most frequently used parameters for wheal response assessment after skin prick testing (SPT). We aimed to compare these 2 parameters taking as gold standard the surface of the wheal skin response. Patients and Methods: Patients suspected of having an allergic reaction against inhalant allergens have been skin prick tested using the Pan-European GA²LEN SPT panel. Fifteen minutes later, macroscopically evident wheal and flare reactions were marked with a pen and transferred to paper with a transparent scotch tape. Each paper-transferred wheal was scanned with an ordinary scanner, and its surface-corresponding maximum perpendicular diameters and longest diameters were measured using a computer software application for image recognition, developed for this purpose. Correlation coefficients (Spearman's ) between surfaces and respective mean (_mean) or longest (_longest) diameters were calculated and subsequently compared. Results: 1,554 SPTs were performed in 74 patients. In 264, a macroscopically evident wheal and flare response was observed. Both mean and longest diameters correlated significantly with the wheal surfaces. However, _longest was statistically significantly larger than _mean when the surface of the wheal was >17 mm² (_longest > 0.860 vs. _mean < 0.660; p < 0.05).Such a surface corresponds to a maximum diameter of approximately 7 mm and a mean diameter of approximately 6 mm. Thus, the larger the surface of the wheal, the more appropriate the usage of the longest diameter. Conclusions: The longest wheal diameter alone seems to be a better surrogate marker of the wheal surface in comparison with the mean diameter. In addition, it is easier and faster to measure. Therefore, we propose this as the optimal methodology to evaluate SPTs.

Copyright © 2009 S. Karger AG, Basel

  Author Contacts

Correspondence to: Dr. George N. Konstantinou
Department of Allergy and Allergy Research Center
National and Kapodistrian University of Athens
41, Fidippidou str, GR-11527 Athens (Greece)
Tel. +30 210 777 6964, Fax +30 210 777 4383, E-Mail gnkonstantinou@gmail.com

  Article Information

Received: May 18, 2009
Accepted after revision: July 16, 2009
Published online: October 22, 2009
Number of Print Pages : 3
Number of Figures : 1, Number of Tables : 1, Number of References : 6