Page 168 - Ebook-Book JCMS 2025

Comparative Analysis of Nasal Challenge Test in Dust Mite
Sensitive Patient, with and without Shrimp Allergy
C. Chumsaengchotsakul1,2*, H. Chantaphakul 1,2
1 Division of Allergy and Clinical Immunology, Department of Medicine, Faculty of Medicine, Chulalongkorn
University
2 King Chulalongkorn Memorial Hospital
*Corresponding Author E-mail: chalermchai_41095@hotmail.com
Background: Abstract
Allergic rhinitis (AR) is a growing issue in Thailand, now affecting over 50% of the
population. Dust mites are the main allergen. While skin prick tests (SPT) and specific IgE
can detect sensitization, they do not always indicate clinical allergy. Cross-sensitization
between dust mites and shrimp, due to shared allergenic proteins like tropomyosin, may
cause shrimp-allergic patients to test positive for dust mites despite lacking clinically
relevant symptoms. This may lead to false-positive results and inaccurate diagnosis of dust
mite-induced AR.
Methods: We conducted an analytical study in 74 adult patients sensitized to dust mites, recruited
from a tertiary allergy clinic. Half of the participants had confirmed shrimp allergy, while
the other half did not. All subjects underwent skin prick testing, measurement of specific
IgE, and nasal challenge testing with standardized dust mite extract. Clinical characteristics,
severity of allergic rhinitis, and history of shrimp allergy were assessed. The primary
objective was to compare nasal challenge outcomes between the two groups and to identify
clinical and immunological factors associated with a positive test result.
Results: Overall, 74.3% of patients had a positive nasal challenge test. Shrimp allergy status was
not associated with test positivity overall (p = 0.79). However, in patients with mild rhinitis,
the presence of shrimp allergy was significantly associated with a lower likelihood of a
positive result (OR: 0.17, 95% CI: 0.03–0.89, p = 0.036). Notably, all shrimp-allergic patients
presenting with oral allergy syndrome exhibited a 100% positive nasal challenge,
underscoring a strong clinical link. Positive responses were also associated with higher
TNSS scores and larger wheal diameters on skin prick tests. Of all the variables analyzed,
only the mean wheal diameter to D. pteronyssinus remained an independent predictor of a
positive nasal challenge in multivariate analysis (adjusted OR 2.71; 95% CI: 1.08–6.82; p =
0.03). Based on subgroup analysis, a wheal size of ≥4.5 mm in non-shrimp-allergic patients
and ≥5 mm in shrimp-allergic individuals provided better diagnostic specificity.
166 Joint Conference in Medical Sciences 2025