Insect sting allergy with negative venom skin test responses

Area of Science:

• Allergy and Immunology
• Insect Sting Reactions
• Diagnostic Testing

Background:

• A significant portion of patients with a history of systemic insect sting reactions were previously excluded from immunotherapy trials due to negative venom skin tests.
• Previous reports indicate that some patients with negative skin tests can experience severe reactions upon subsequent stings.

Purpose of the Study:

• To raise awareness regarding insect sting allergy in patients with negative skin test responses.
• To determine the frequency and clinical significance of negative venom skin test results in individuals with a documented history of systemic reactions to insect stings.

Main Methods:

• Prospective examination of negative venom skin test prevalence in patients with a history of systemic sting reactions.
• Analysis of retesting outcomes and sting challenge results in consenting patients.

Main Results:

• Out of 307 patients, 32% had negative venom skin tests. Of these, 36% had positive repeat skin tests or low positive RAST, and 7% had high IgE levels.
• Notably, 57% of patients with negative skin tests and positive histories had negative RAST results.
• Systemic reactions occurred in 21% of patients with positive skin tests and 22% of those with negative skin tests (24% with positive RAST, 14% with negative RAST).

Conclusions:

• Negative venom skin tests do not exclude the possibility of future systemic sting reactions.
• A substantial number of patients with a history of systemic sting reactions exhibit negative skin tests, sometimes accompanied by positive venom-specific IgE antibody levels.
• Repeat venom skin testing and serologic IgE antivenom testing are recommended for patients with negative initial skin tests; improved diagnostic reagents are needed.