Lack of Correlation between Severity of Clinical Symptoms, Skin Test Reactivity, and Radioallergosorbent Test Results in Venom-Allergic Patients.
OBJECTIVE
To retrospectively examine the relation between skin test reactivity, venom-specific immunoglobulin E (IgE) antibody levels, and severity of clinical reaction in patients with insect venom allergy.


METHODS
Thirty-six patients (including 15 females) who presented with a history of allergic reactions to insect stings were assessed. The mean age at the time of the reactions was 33.4 +/- 15.1 years (range, 4-76 years), and patients were evaluated 43.6 +/- 90 months (range, 1-300 months) after the reactions. Clinical reactions were scored according to severity, from 1 (cutaneous manifestations only) to 3 (anaphylaxis with shock). These scores were compared to scores for skin test reactivity (0 to 5, indicating the log increase in sensitivity from 1 mug/mL to 0.0001 mug/mL) and radioallergosorbent test (RAST) levels (0 to 4, indicating venom-specific IgE levels, from undetectable to >17.5 kilounits of antigen per litre [kUA/L]).


RESULTS
No correlation was found between skin test reactivity (Spearman's coefficient = 0.15, p = .377) or RAST level (Spearman's coefficient = 0.32, p = .061) and the severity of reaction. Skin test and RAST scores both differed significantly from clinical severity (p < .05), but there was a significant correlation between skin test reactivity and RAST score (p = .042). There was no correlation between skin test reactivity and time since reaction (Spearman's coefficient = 0.18, p = .294) nor between RAST and time since reaction (r = 0.1353, p = .438). Elimination of patients tested more than 12 months after their reaction still produced no correlation between skin test reactivity (p = .681) or RAST score (p = .183) and the severity of the clinical reaction.


CONCLUSIONS
In venom-allergic patients (in contrast to reported findings in cases of inhalant IgE-mediated allergy), there appears to be no significant correlation between the degree of skin test reactivity or levels of venom-specific IgE (determined by RAST) and the severity of the clinical reaction.
Departments of Medicine and Immunology, University of Manitoba, Winnipeg, Manitoba. rwarrington@hsc.mb.ca.
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