Allergic skin test is a commonly used test to evaluate an immediate immune response either by skin prick test (SPT) or intradermal test. SPT is widely used Several methods have been proposed to interpret SPT. However, there has been no comparison study about inter-test relationship. The aim of this study compare three different interpreting methods and define the relationship among them.
Methods
We examined SPT to 147 patients who visited allergy clinic complaining of nasal symptoms from January to December 2014.Three different interpreting methods were used for defining positivity in SPT such as interpretation by comparing wheal sizes of allergen and histamine , the biggest diameter of the wheal size more than 3 mm , and the biggest diameter of the erythema greater than 15 mm. And we compared the positivity among 3 different interpretation methods. The validity of each interpreting method was evaluated by comparing positivity to TNSS.
Result
Positivity in SPT were reported as 48.2% in A/H ratio method, 64.0% in Wheal size method and in Erythema size method, respectively. Subjects who showed negative result in A/H ratio method have positive results in Wheal size method and Erythema size method were 15.8%, respectively. Subjects showing negative result in A/H ratio but positive result in Erythema size and Wheal size method had significantly higher rhinorrhea, nasal obstruction and TNSS than subjects showing both negative results.
Conclusion
Comparing TNSS in each method, TNSS of SPT positive group is higher than those of negative group, except TNSS of Nasal obstruction of A/H method. Thus diagnosing allergic rhinitis patients, we may consider Wheal size method and Erythema size method than A/H ratio method.