Sensitization to Cat: When Is Nasal Challenge Needed?

Area of Science:

• Allergy and Immunology
• Otorhinolaryngology

Background:

• The skin prick test (SPT) is a standard diagnostic for cat allergy in perennial allergic rhinitis (PER).
• Determining the minimum SPT wheal size to confirm true cat allergy versus sensitization is debated.
• The cat nasal challenge test (cNCT) is considered the gold standard for diagnosing true cat allergy.

Purpose of the Study:

• To compare cNCT positivity in cat owners versus non-owners with PER.
• To establish an optimal SPT wheal size cutoff for predicting positive cNCT in PER patients.
• To guide allergen immunotherapy (AIT) decisions for cat allergy.

Main Methods:

• 60 adult PER patients underwent cNCT via nasal spray.
• Participants included cat owners (n=19) and non-owners (n=41) with positive cat SPT.
• Nasal response was assessed using subjective (TNSS) and objective (PNIF, NEo) measures; PEF monitored safety.

Main Results:

• No significant differences in SPT wheal size or cNCT positivity were found between cat owners and non-owners.
• A cat SPT wheal size > 6.5 mm predicted positive cNCT with 71.11% sensitivity and 100% specificity.
• This cutoff effectively identifies true cat allergy.

Conclusions:

• Cat allergy prevalence is similar in owners and non-owners with PER.
• An SPT wheal size of ≥6.5 mm can reliably identify true cat allergy.
• This threshold may help avoid the cNCT for patients needing cat AIT.