1. (SHRIMP SENSITIZED ON AIT) 5 failed OFC + 5 w/ hx of anaphylaxis
rPen a 1 Improves Clinical Predictability of Shrimp Allergy Compared to Skin Prick Testing
K.S. Tuano1,2, A. Casillas2, S. Anvari1, J. Hajjar1,2, I.C. Hanson1, F. Seeborg1, L.M. Noroski1, D. Guffey3, G. Kang1, C.M. Davis1
1 Section of Immunology, Allergy and Rheumatology, Department of Pediatrics, Texas Children’s Hospital, Baylor College of Medicine, Houston, TX
2 Section of Immunology, Allergy and Rheumatology, Department of Medicine,, Baylor College of Medicine, Houston, TX
3 Dan L. Duncan Institute for Clinical and Translational Research, Baylor College of Medicine, Houston, Texas
Background
Results
Results
Results
Figure 1: Study design.
Figure 5: (A) Shrimp sIgE correctly identifies shrimp allergy in 84.12%. (B) rPen a 1 correctly identifies shrimp allergy in 84.21%.
Shellfish is one of the most common causes of food allergy in both children and adults worldwide
Shellfish is the one of the most common food implicated in emergency department food-allergic events
Current diagnostic limitations:
Skin prick test (SPT) – lack of predictive values
Specific IgE (sIgE) – lack of level that would predict 95% probability of clinical reaction compared to other food allergens
Allergen immunotherapy (AIT) may modulate IgE levels, caution interpreting sIgE for immunotherapy.
Figure 2: Clinical data by history on subjects recruited. Cutaneous and oral symptoms are most common in shrimp allergic subjects.
Pediatric and adult subjects:
Clinical history of reaction upon ingestion of shrimp
Shellfish avoidance due to elevated sIgE to shrimp and/or positive shrimp SPT
22 total subjects
16 children
6 adults
17 underwent OFC
3 excluded in analysis
(SHRIMP SENSITIZED ON AIT)
14 included in analysis
9 passed OFC
(SHRIMP SENSITIZED)
5 failed OFC + 5 w/ hx of anaphylaxis
(SHRIMP ALLERGIC)
5 w/ hx of anaphylaxis
Shrimp IgE = 1.12 kUA/L
Sensitivity = 90%
Specificity = 77.8%
AUC = (95% CI: 0.71, 1.00)
rPen a 1 = 0.72 kUA/L
Sensitivity = 80%
Specificity = 89%
AUC = (95% CI: 0.68,
1.00)
Discussion
Figure 3: Shrimp sIgE (A) and rPen a 1 (B) are higher in shrimp allergic subjects compared to shrimp sensitized patients. SS, shrimp sensitized; SA, shrimp allergic.
In shrimp allergic subjects compared to shrimp sensitized subjects:
History and symptoms are non-specific and may not be helpful
Shrimp SPT may not be a reliable diagnostic tool in identifying shrimp allergy.
Shrimp IgE is higher (10.2 kUA/L vs. 0.8 kUA/L)
Pen a 1 is higher (3.79 kUA/L vs kUA/L)
Rationale
There is lack of data in predicting shrimp allergy using SPT, sIgE and rPen a 1 (also known as tropomyosin).
We aim to associate SPT, sIgE to shrimp and rPen a 1 with clinical reactivity of patients with a history of adverse reactions to shrimp through oral food challenge IOFC).
(A)
(B)
p = 0.004
p =
Table 1: Demographic and clinical data on subjects recruited.
Methods
Shrimp Allergy
(n=10)
Shrimp Tolerant
(n=9)
p-value
Age, yr
Median (range) 9
(4-45) 7
(3-65)
0.30
Male:Female
7:3
6:3
0.99
Hx of asthma, %
90%
78%
0.53
Hx of allergic rhinitis, %
100%
Hx of other food allergy, %
20%
33%
0.14
Hx of eczema, %
30%
56%
0.33
Timing of symptoms:
immediate
10 mins
> 10 mins
83%
17%
29%
43%
Positive shrimp SPT, % (n)
80%
67%
0.63
Conclusions
Inclusion criteria:
Subjects with history of adverse reactions upon shrimp ingestion and positive sIgE and/or SPT.
Subjects avoiding shellfish due to history of elevated sIgE to shrimp and/or positive shrimp SPT
Exclusion criteria:
Patients on AIT.
SPT to shrimp (extract, cooked and raw), shrimp sIgE and rPen a 1 were analyzed.
Shrimp OFC – 16 grams of shrimp protein
Fisher’s exact test, Kruskall-Wallis and receiver operating characteristic analysis were performed.
Study approved by Baylor College of Medicine IRB.
rPen a 1  0.72kUA/L and/or shrimp sIgE  1.12kUA/L are useful to predict clinical reactivity in 84% of patients with suspected shrimp allergy potentially obviating the need for an OFC.
rPen a 1 is more specific and maybe a useful adjunct with SPT and shrimp sIgE in diagnosis of shrimp allergy.
Shrimp IgE is less specific and may result in over diagnosis of shrimp allergy. SS SA SS SA
Figure 4: Shrimp SPT (extract, cooked and raw forms) does not differentiate shrimp allergic from shrimp sensitized subjects.
p = 0.63
p = 0.57
p = 0.99
Acknowledgements
Thermo Fisher Scientific Phadia for receiving research grant
Contact Information:
Karen Thursday S. Tuano, MD