Which skin prick test wheal size detects true allergy to Salsola kali?
Al-A. Mona Alahmadm@hsc.edu.kw1,2, J. Edin3, A. Nermina1Show more: Authors information and Publication history1Al Rashed Allergy Centre, Kuwait
2Microbiology Department, Faculty of Medicine, Kuwait University, Safat, Kuwait
3Medical Faculty, University of Tuzla, Tuzla, Bosnia and Herzegovina
History:
Published online: 18 June 2020
Accepted: 18 June 2020
Received: 2 January 2020
Doihttp://doi.org/10.23822/EurAnnACI.1764-1489.161
SummaryBackground. Sensitization to Salsola kali (Sk) weed pollen allergen is the most common cause of seasonal allergic rhinitis (SAR) in Middle East countries. Aim. To identify Salsola kali skin prick test (SkSPT) wheal size cut-off, able to determine true allergy among adult patients with moderate to severe SAR, who are in need of Salsola kali allergen specific immunotherapy (SkAIT).
Methods. In 151 adults with moderate to severe SAR, mean age 32.79 ± 10.79 years, of both gender (females: 43.05%), with a positive SkSPT, (i.e. cut off wheal longest diameter of 3 mm) and one or more other local weed pollens, Salsola kali nasal provocation test (SkNPT) was carried out. Response was assessed both subjectively, with scores, and objectively, by measuring peak nasal inspiratory flow (PNIF). Safety profile of SkNPT was assessed using peak expiratory flow rate (PEF) measurements.
Results. SkNPT positive response was found in 125 patients (82.78%). Mean skin prick test (SPT) wheal size to Sk was bigger in the nasal provocatin test (NPT) positive group (9 mm) compared to the NPT negative patients (5 mm), p<0.0001. ROC analysis showed that a SPT wheal size to Sk at the threshold of >7.5 mm enabled identification of SkNPT positivity with a sensitivity of 73.6% and specificity of 100.0% (area under the curve 0.9498, standard error 0.01808; 95% confidence interval (CI): 0.9144 to 0.9853; p<0.0001).
Conclusions. SPT wheal size of 3 mm might overestimate the presence of real allergy to Sk in a desert environment. A SPT wheal size >7.5 mm for Sk appears to distinguish individuals who develop disease from those who does not. Physicians should select the proper SPT wheal size value as an appropriate criterion according to the allergen than using a uniform cut off value in patients eligible for SkAIT.
Key words
Salsola kali; skin prick test; nasal provocation test; allergy; sensitivity; specificity.
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