Clinical Relevance of Immunologic Diagnosis of Shrimp Allergy in Adults.

PURPOSE

Shrimp is a predominant allergic food in adults and adolescents. This study aims to evaluate the clinical efficacy of immunologic diagnosis in differentiating the clinical phenotypes of shrimp allergy.

METHODS

We enrolled 85 adults diagnosed with shrimp allergy based on clinical symptoms that occurred at least twice after shrimp ingestion and who had specific immunoglobulin E (IgE) results for shrimp extract, were enrolled in the study. Patients were classified into 2 groups: anaphylaxis (ANA) and non-ANA. Serum-specific IgEs to shrimp and recombinant tropomyosin from both house dust mite (HDM) and shrimp were measured using ImmunoCAP.

RESULTS

Among the patients (mean age 38 years; 51.8% female), 32 were diagnosed with shrimp-induced ANA. The remaining 53 were classified into the non-ANA group, including 46 acute urticaria/angioedema and 7 isolated oropharyngeal manifestations. There were no significant differences in shrimp-specific IgE positivity (78.1% vs. 60.4%) or skin prick test (SPT) positivity (16.7% vs. 25.9%) between groups. However, specific IgE to shrimp extract was significantly higher in the ANA group. Receiver operating characteristic analysis indicated that a shrimp-specific IgE level > 0.7 kU/L was an appropriate cutoff for identifying ANA among patients with shrimp allergy (area under the curve 0.643, = 0.028). No significant differences were observed in specific IgEs to recombinant shrimp and the HDM tropomyosin between the groups. The ANA group had a greater prevalence of nonsteroidal anti-inflammatory drug hypersensitivity (31.3% vs. 7.5%, = 0.006) and chronic urticaria (35.5% vs. 15.4%, = 0.035).

CONCLUSIONS

Patients with shrimp-induced ANA presented higher levels of specific IgE to shrimp extract compared to those with acute urticaria or localized oropharyngeal symptoms. Neither SPTs nor specific IgE tests for recombinant tropomyosin effectively differentiate ANA among shrimp allergy patients.