1. Skin or In Vitro Test for Food Allergy? Skin Test
Linda Cox, FAAAI, FACAAI
WAO 2011 Meeting
Cancun, Mexico

2. Linda Cox, MD Disclosure
Allergist/Immunologist: solo private practice
Associate Clinical Professor of Medicine Nova Southeastern University
Medical advisory board/consultant: Stallergenes, Genentech/Novartis, ISTA
Speakers fee: Thermo Fisher, Baxter
Organizational interests:
FDA Allergenic Products Advisory Committee –consultant
AAAAI-Secretary/Treasurer
Joint Task Force on Practice Parameters-member
ABAI Board of Directors -member

3. Skin or In Vitro Test for Food Allergy Learning Objectives
To recognize that, in general, allergy skin tests are the preferred tests for food allergy diagnosis for several reasons
Be able to discuss scenarios in which skin test may be superior to serum specific-IgE

4. Neither skin or serum sIgE have 100% sensitivity or specificity
Significance Of Positive Allergy Skin Test Results Food Allergy Diagnostic Testing Pearls, Pitfalls and the Gold Standard
Allergy tests yield information on sensitization, which is not always equivalent to clinical allergy.
Neither skin or serum sIgE have 100% sensitivity or specificity
The double-blind, placebo-controlled food challenge is the gold standard for food allergies but it is
a time-consuming procedure that is
limited to trained allergy specialists and
carries the risk of producing a severe reaction

5. Food-specific IgE Antibody Concentrations or Skin Test Size Correlate with Risk of Clinical Reactivity
Curve varies by:
Food
Disease
Age
Assay (brand)
At certain high IgE values,
the chance of a clinical
reaction approaches certainty
One study, one test brand,
children age 5: Egg- 7 kUa/L
Milk 15 kIU/L, Peanut 14 kUa/L
The higher the concentration of food-specific IgE antibodies, the more likely there will be a clinical response to the food ingested. Some studies (which so far have addressed only certain assay systems, a few foods and limited age groups and disorders) show that at particular high IgE values, the chance of clinical reactions is almost certain. However, the exact “diagnostic level” has varied somewhat among studies. It is apparent that age, disease, and possibly other subtle nuances account for differing results among studies thus far. Caution is needed in test interpretation. It is clear that the curve shown here for illustration only varies according to the food tested, age of patient, and disease under consideration. The IgE antibody results using Phadea ImmunoCAP in one study in atopic children at about age 5 years is shown. In several studies among several foods, persons with “undetectable” levels of food-specific- IgE have had reactions upon oral food challenge. This observation indicates the importance of applying historical information in the context of test interpretation and, as indicated, to consider additional evaluations (e.g., allergy prick skin tests, physician-supervised oral food challenges) when suspicion of allergy is high but serum tests are undetectable. It is important to realize that “predictive” values are not available for most foods and has not been tested with similar results in numerous populations.
References
Celik-Bilgili S, Mehl A, Verstege A, Staden U, Nocon M, Beyer K et al. The predictive value of specific immunoglobulin E levels in serum for the outcome of oral food challenges. Clin Exp Allergy 2005; 35(3):268-73
Perry TT, Matsui EC, Kay Conover-Walker M, Wood RA. The relationship of allergen-specific IgE levels and oral food challenge outcome. J Allergy Clin Immunol 2004; 114(1):144-9
Knight AK, Shreffler WG, Sampson HA, Sicherer SH, Noone S, Mofidi S et al. Skin prick test to egg white provides additional diagnostic utility to serum egg white-specific IgE antibody concentration in children. J Allergy Clin Immunol 2006; 117(4):842-7
Roberts G, Lack G. Diagnosing peanut allergy with skin prick and specific IgE testing. J Allergy Clin Immunol 2005; 115(6):1291-6
Garcia-Ara C, Boyano-Martinez T, Diaz-Pena JM, Martin-Munoz F, Reche-Frutos M, Martin-Esteban M. Specific IgE levels in the diagnosis of immediate hypersensitivity to cows' milk protein in the infant. J Allergy Clin Immunol 2001; 107(1):
Mehl A, Rolinck-Werninghaus C, Staden U, Verstege A, Wahn U, Beyer K, Niggemann B. The atopy patch test in the diagnostic workup of suspected food-related symptoms in children. J Allergy Clin Immunol Oct;118(4):923-9
Sampson HA. Utility of food-specific IgE concentrations in predicting symptomatic food allergy. J Allergy Clin Immunol 2001; 107(5):891-6
Sampson HA, Ho DG. Relationship between food-specific IgE concentrations and the risk of positive food challenges in children and adolescents. J Allergy Clin Immunol 1997; 100(4):444-51
Sporik R, Hill DJ, Hosking CS. Specificity of allergen skin testing in predicting positive open food challenges to milk, egg and peanut in children. Clin Exp Allergy 2000;30:
Negative test is not zero risk
Sampson HA.. J Allergy Clin Immunol 2001;107:891-6.

6. 50% and 95% Predictive Value have been Established for Food Specific-IgE and SPT
Nowak-WÄ A, Assa'ad A, Bahna S, Bock A, S S, Teuber S. Work Group report: Oral food challenge testing. J Allergy Clin Immunol 2009;123:S365-S83.
Oral food challenges are procedures conducted by allergists/immunologists to make an accurate diagnosis of immediate, and occasionally delayed, adverse reactions to foods. The timing of the challenge is carefully chosen based on the individual patient history and the results of skin prick tests and food specific serum IgE values. The type of the challenge is determined by the history, the age of the patient, and the likelihood of encountering subjective reactions. The food challenge requires preparation of the patient for the procedure and preparation of the office for the organized conduct of the challenge, for a careful assessment of the symptoms and signs and the treatment of reactions. The starting dose, the escalation of the dosing, and the intervals between doses are determined based on experience and the patient's history. The interpretation of the results of the challenge and arragements for follow-up after a challenge are important. A negative oral food challenge result allows introduction of the food into the diet, whereas a positive oral food challenge result provides a sound basis for continued avoidance of the food
Food specific-IgE measured with ImmunoCap™ and SPT with lancet (ref 17 & 21,) and bifurcated needle (ref 22)
Nowak-WÄ et al, Work Group report: Oral food challenge testing. J Allergy Clin Immunol 2009; 123:S365-S83.

7. Specificity of SPT in predicting positive open food challenges to milk, egg and peanut in children
Study: 555 challenges were undertaken in 467 children with suspected food allergy. Positive challenge if objective signs seen; negative, if the child could tolerate normal food daily, for 1 week.
Results: 55% were positive, 37% negative, and 8% inconclusive.
Possible to identify a SPT wheal at, and above, which negative reactions did not occur (100% specificity ):
cow milk, 8mm
egg, 7mm
peanut, 8mm
However positive reactions could occur with a SPT of 0 mm.
BACKGROUND: The specificity of allergen skin prick testing to diagnose clinically relevant food allergy is controversial. OBJECTIVES: To determine the specificity of the allergen weal diameter to correctly identify children who react on formal open food challenges. METHODS: Over a 9-year period children referred to a tertiary allergy clinic for the evaluation of suspected food allergy were prospectively studied. Allergen skin prick testing to cow milk, egg white and peanut extracts (Dome-Hollister-Stier, Spokane, WA, USA) was undertaken using a lancet technique. All children underwent open food challenges to the relevant food(s) in a hospital clinic. Challenges were classified as positive, if objective signs were seen; negative, if the child could tolerate normal quantities of the food, daily, for one week; or inconclusive if none of the former criteria were met. RESULTS: Five hundred and fifty-five challenges were undertaken in 467 children: 339 challenges to cow milk, 121 to egg, and 95 to peanut. Fifty-five percentage of challenges were positive, 37% negative, and 8% inconclusive. For each food it was possible to identify a skin weal diameter at, and above, which negative reactions did not occur: cow milk, 8 mm; egg, 7 mm; peanut, 8 mm. In contrast, positive reactions could occur with a skin wheal diameter of 0 mm. CONCLUSIONS: In this high risk referral population it was possible to define skin weal diameters to egg, milk and peanut above which open oral food challenges were positive (100% specificity). By utilizing these measurements the need for formal food challenges can be reduced.
Sporik R, Hill DJ, Hosking CS. Specificity of allergen skin testing in predicting positive open food challenges to milk, egg and peanut in children. Clin Exp Allergy. 2000;30(11): Epub 2000/11/09.
Sporik et al, Clin Exp Allergy. 2000;30(11):

8. Positive open food challenges to milk, egg and peanut in children could occur with 0 mm SPT
MILK PEANUT
BACKGROUND: The specificity of allergen skin prick testing to diagnose clinically relevant food allergy is controversial. OBJECTIVES: To determine the specificity of the allergen weal diameter to correctly identify children who react on formal open food challenges. METHODS: Over a 9-year period children referred to a tertiary allergy clinic for the evaluation of suspected food allergy were prospectively studied. Allergen skin prick testing to cow milk, egg white and peanut extracts (Dome-Hollister-Stier, Spokane, WA, USA) was undertaken using a lancet technique. All children underwent open food challenges to the relevant food(s) in a hospital clinic. Challenges were classified as positive, if objective signs were seen; negative, if the child could tolerate normal quantities of the food, daily, for one week; or inconclusive if none of the former criteria were met. RESULTS: Five hundred and fifty-five challenges were undertaken in 467 children: 339 challenges to cow milk, 121 to egg, and 95 to peanut. Fifty-five percentage of challenges were positive, 37% negative, and 8% inconclusive. For each food it was possible to identify a skin weal diameter at, and above, which negative reactions did not occur: cow milk, 8 mm; egg, 7 mm; peanut, 8 mm. In contrast, positive reactions could occur with a skin wheal diameter of 0 mm. CONCLUSIONS: In this high risk referral population it was possible to define skin weal diameters to egg, milk and peanut above which open oral food challenges were positive (100% specificity). By utilizing these measurements the need for formal food challenges can be reduced.
Sporik R, Hill DJ, Hosking CS. Specificity of allergen skin testing in predicting positive open food challenges to milk, egg and peanut in children. Clin Exp Allergy. 2000;30(11): Epub 2000/11/09.
Sporik et al, Clin Exp Allergy. 2000;30(11):

9. Diagnostic accuracy of skin prick testing in children with tree nut allergy
Study: 906 tree nut and peanut challenges in 680 child aged 4 month to 19 years
Results :
8 mm SPT weal diameters >95% accuracy in predicting a positive OFC for cashew, hazel nut, walnut, and sesame.
Using the predictive SPT decision points, the need for OFC was reduced by 33% (peanut), 56% (tree nuts), and 53% (sesame),
Not able to determine the 95% PPV for almond, pistachio, pecan, and brazilnut
Ho et al J Allergy Clin Immunol 2006;117:1506-8

10. The predictive value of the skin prick test weal size for the outcome of oral food challenges.
Study: 735 OFC in 385 children (median age 22 months), with cow's milk, hen's egg, wheat and soy.
Results: 312 (43%) OFC were assessed to be positive.
95% and 99% predicted probabilities using logistic regression revealed predictive decision points of:
13.0 and 17.8 mm for HE
12.5 and 17.3 mm for CM
ACKGROUND: The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of food allergy. Objective To evaluate the diagnostic capacity of the SPT in predicting the outcome of oral food challenges, and to determine decision points for the weal size and the skin index (SI) that could render double-blind, placebo-controlled food challenges unnecessary. METHODS: In 385 children (median age 22 months), 735 controlled oral challenges were performed with cow's milk (CM), hen's egg (HE), wheat and soy. Three hundred and thirty-six of 385 (87%) children suffered from atopic dermatitis. SPT was performed in all children. Diagnostic capacity, receiver-operator characteristics (ROC) curves and predictive decision points were calculated for the mean weal size and the calculated SI. RESULTS: Three hundred and twelve of 735 (43%) oral food challenges were assessed to be positive. Calculation of 95% and 99% predicted probabilities using logistic regression revealed predictive decision points of 13.0 and 17.8 mm for HE, and 12.5 and 17.3 mm for CM, respectively. However, using the SI, the corresponding cut-off levels were 2.6 and 3.7, respectively, for HE, and 2.7 and 3.7 for CM. For wheat, 95% and 99% decision points of 2.2 and 3.0 were found in children below 1 year of age. CONCLUSION: Predictive decision points for a positive outcome of food challenges can be calculated for HE and CM using weal size and SI. They may help to avoid oral food challenges.
Verstege A, Mehl A, Rolinck-Werninghaus C, Staden U, Nocon M, Beyer K, et al. The predictive value of the skin prick test weal size for the outcome of oral food challenges. Clin Exp Allergy. 2005;35(9):
Verstege et al. Clin Exp Allergy. 2005;35(9):

11. Results: 49% of challenges were positive
SPT Wheal Size May Useful in Predicting Presence of Absence of Clinical Allergy
Study : Challenged 47 peanut-naïve children who had a positive SPT to peanut (smallpox needle)
Results: 49% of challenges were positive
Mean wheal: negative group 6.3 mm vs. positive group 10.3 mm
Using the cutoff of a > 5 mm wheal on PST, peanut challenge yielded
Sensitivity was 100% (no false -)
Specificity was 12.5% (high false+)
Negative predictive value was 100%
Positive predictive value was 52%.
Conclusion: These findings suggest peanut PST of 3 or 4 mm could undergo less resource-intensive, accelerated challenges.
BACKGROUND: Although allergy testing before food ingestion is generally not recommended, many peanut-naive children undergo prick skin tests (PSTs) to peanut because of atopy. Children with positive PSTs are generally advised to avoid peanuts either indefinitely or until a definitive diagnosis is made through challenge. OBJECTIVE: To describe peanut challenges in atopic, peanut-naive children with PST to peanuts > or = 3 mm and the PST properties in this population. METHODS: Between 1994 and 2001, 47 patients were identified who had a positive peanut PST, no previous peanut ingestion, and had undergone a peanut challenge. RESULTS: Forty-nine percent of the challenges were positive. The mean of the largest wheal diameter (95% confidence interval [CI]) of the PST in children having a negative and positive challenge was 6.3 mm (CI, 5.3 to 7.3) and 10.3 mm (CI, 8.9 to 11.8), respectively. At a PST cutoff of > or = 5 mm, the sensitivity and negative predictive value (95% CI) was 100% (85.2 to 100) and 100% (29.2 to 100), whereas the specificity and positive predictive value (95% CI) was 12.5% (2.7 to 32.4) and 52.3% (36.7 to 67.5), respectively. CONCLUSIONS: We show that 49% of atopic, peanut-naive children sensitized to peanut developed allergic symptoms during oral provocation with peanut. Although the sensitivity of the PST at > or = 5 mm for the detection of peanut allergy in this study was 100%, our small sample size limits the applicability of this value. Further investigation is needed to determine whether children with wheal diameters of 3 or 4 mm, perhaps coupled with low peanut-specific IgE, could undergo less resource-intensive, accelerated challenges.
agan R, Hayami D, Joseph L, St Pierre Y, Clarke AE. The predictive value of a positive prick skin test to peanut in atopic, peanut-naive children. Ann Allergy Asthma Immunol. 2003;90(6):640-5.
Kagan R et al., Ann Allergy Asthma Immunol  2003 Jun;90(6):640-5:

12. Study: 89 in-hospital challenges: positive in 56/89 (62.9%) patients:
Prediction of anaphylaxis during peanut food challenge: usefulness of peanut SPT & specific IgE
Study: 89 in-hospital challenges: positive in 56/89 (62.9%) patients:
In the 55 completed challenges: 28 no rx, 6 reaction without anaphylaxis, 21 had anaphylaxis
Mean peanut SPT wheal size and specific IgE level were associated with the severity of reactions on challenge
Wainstein et al ;21(4 Pt 1):603-11

13. Allergy Skin Testing Advantages
In the allergist office, skin testing remains the central test to confirm allergic sensitivity.1
Advantages:
Skin testing is fast (15-30 minutes), safe, sensitive and involves minimally invasive procedures
Can provide information on allergen sensitivity on initial clinic visit.
i.e., no trip to a busy lab for venipuncture
Cost-effective in terms of patient time & money
When performed correctly, skin testing is reproducible
1. Oppenheimer et al, Ann Allergy 2006;S1:6-122.

14. Serological Evaluation for Sensitization to Food
Limitations
Cost-patient time & money
Requires venipuncture/or other blood draw
Modest sensitivity/specificity lead to false positive and false negative
Although anyone can order still requires experienced clinician to optimally interpret data
Reactions could occur despite a “negative” test
Several studies show reaction rates over 20% in patients with “undetectable” food specific serum IgE (with suspected allergy by history)
Different Lab assay systems are not interchangeable
Advantages over skin tests: they can be performed while a patient is using antihistamines or if a patient has an extensive rash.
It must be appreciated that certain food-responsive disorders are rarely (food-protein-induced enterocolitis syndrome) or only sometimes (eosinophilic esophagitis) associated with detectable food-specific IgE antibodies.
References
Sampson HA, Anderson JA. Summary and recommendations: Classification of gastrointestinal manifestations due to immunologic reactions to foods in infants and young children. J Pediatr Gastroenterol Nutr 2000 ;30 Suppl :S Suppl:S87-94:S87-S94
Sampson HA, Sicherer SH, Birnbaum AH. AGA technical review on the evaluation of food allergy in gastrointestinal disorders. American Gastroenterological Association. Gastroenterol 2001; 120(4):
Adapted from : the Pearls & Pitfalls of Allergy Diagnostic Testing CME presentation at

15. Serum specific-IgE Antibody Laboratory Results Interassay Variability
Objective: compare results from CLIA-certified laboratories that used 3 common systems for sIgE antibody
Methods: 60 samples for peanut and 20 for soy and mouse-human chimeric IgE antibodies specific for the Bet v 1 and Der p 2 were submitted for sIgE measurement on 3 different systems:
ImmunoCAP, Immulite, and Turbo-RAST
Reference: total IgE = Chimeric IgE
Wood et al., Annals Allergy, Asthma & Immunol 2007; 99:34-41

16. Poor Agreement of IgE Antibody Laboratory Results
Results: Poor agreement among the 3 systems for soy and peanut
Using a cutoff of 0.35 kUa/L showed some differences in the ability to detect sIgE sensitization with Turbo RAST most variable
Studies suggest various assays measure different populations of IgE antibody.
Currently, it is not known which of the major assays provides the most accurate evaluation of allergen s-IgE in patients’ serum.
Wood et al, Annals Allergy, Asthma & Immunol 2007; 99:34-41

17. Interassay Variability of IgE Antibody Laboratory Results
Results: Chimeric antibodies: Widely disparate results amongst the 3 assays
Immunlite considerably overestimated sIgE
Turbo RAST underestimated sIgE
Immunlite
ImmunoCAP
Tubo RAST
Wood et al.,Annals Allergy, Asthma & Immunol 2007; 99:34-41

18. Allergy Skin Testing Advantages & Diagnostic Utility in Comparison to Specific- IgE Antibody
SPT may be more sensitive in predicting who will react on challenge
In pts with low food sIgE, SPT may have diagnostic utility
SPT can identify sensitivity to labile food proteins

19. The natural history of peanut allergy
Study: 223 peanut allergic pts 4 to 20 yrs were evaluated by questionnaire, skin testing, & peanut sIgE
Reaction-free plus peanut sIgE ≤ 20 kUa/L challenged
Results: 85 pts underwent DBPC or open challenge
48 (21.5%) patients passed challenge (‘outgrew allergy’)
37 failed challenge: 8(21%) patients with negative peanut sIgE , 2 of which also had negative SPT
BACKGROUND: It has traditionally been assumed that peanut allergy is rarely outgrown. OBJECTIVE: The goal of this study was to determine the number of children with peanut allergy who become tolerant of peanut. METHODS: Patients aged 4 to 20 years with a diagnosis of peanut allergy were evaluated by questionnaire, skin testing, and a quantitative antibody fluorescent-enzyme immunoassay. Patients who had been reaction free in the past year and had a peanut IgE (PN-IgE) level less than 20 kilounits of antibody per liter (kU(A)/L) were offered an open or double-blind, placebo-controlled peanut challenge. RESULTS: A total of 223 patients were evaluated, and of those, 85 (PN-IgE < kU(A)/L [median 1.42 kU(A)/L]) participated in an oral peanut challenge. Forty-eight (21.5%) patients had negative challenge results and were believed to have outgrown their peanut allergy (aged years [median 6 years]; PN-IgE < kU(A)/L [median 0.69 kU(A)/L]). Thirty-seven failed the challenge (aged 4-13 years [median 6.5 years]; RAST < kU(A)/L [median 2.06 kU(A)/L]). Forty-one patients with PN-IgE levels less than 20 kU(A)/L declined to undergo challenge, and 97 were not eligible for challenge because their PN-IgE levels were greater than 20 kU(A)/L or they had had a recent reaction. Sixty-seven percent of patients with PN-IgE levels less than 2 kU(A)/L and 61% with levels less than 5 kU(A)/L had negative challenge results. Of those who underwent challenge, PN-IgE levels for those who passed versus those who failed were different at the time of challenge (P = .009), but not at the time of diagnosis (P = .25). CONCLUSION: This study demonstrates that peanut allergy is outgrown in about 21.5% of patients. Patients with low PN-IgE levels should be offered a peanut challenge in a medical setting to demonstrate whether they can now tolerate peanuts.
Skolnick et al,J Allergy Clin Immunol. 2001;107(2):367-74

20. The natural history of peanut allergy Peanut IgE level at diagnosis not predictive
Peanut sIgE levels for those who passed vs those who failed were different at the time of challenge (P = .009), but not at the time of diagnosis (P = .25).
BACKGROUND: It has traditionally been assumed that peanut allergy is rarely outgrown. OBJECTIVE: The goal of this study was to determine the number of children with peanut allergy who become tolerant of peanut. METHODS: Patients aged 4 to 20 years with a diagnosis of peanut allergy were evaluated by questionnaire, skin testing, and a quantitative antibody fluorescent-enzyme immunoassay. Patients who had been reaction free in the past year and had a peanut IgE (PN-IgE) level less than 20 kilounits of antibody per liter (kU(A)/L) were offered an open or double-blind, placebo-controlled peanut challenge. RESULTS: A total of 223 patients were evaluated, and of those, 85 (PN-IgE < kU(A)/L [median 1.42 kU(A)/L]) participated in an oral peanut challenge. Forty-eight (21.5%) patients had negative challenge results and were believed to have outgrown their peanut allergy (aged years [median 6 years]; PN-IgE < kU(A)/L [median 0.69 kU(A)/L]). Thirty-seven failed the challenge (aged 4-13 years [median 6.5 years]; RAST < kU(A)/L [median 2.06 kU(A)/L]). Forty-one patients with PN-IgE levels less than 20 kU(A)/L declined to undergo challenge, and 97 were not eligible for challenge because their PN-IgE levels were greater than 20 kU(A)/L or they had had a recent reaction. Sixty-seven percent of patients with PN-IgE levels less than 2 kU(A)/L and 61% with levels less than 5 kU(A)/L had negative challenge results. Of those who underwent challenge, PN-IgE levels for those who passed versus those who failed were different at the time of challenge (P = .009), but not at the time of diagnosis (P = .25). CONCLUSION: This study demonstrates that peanut allergy is outgrown in about 21.5% of patients. Patients with low PN-IgE levels should be offered a peanut challenge in a medical setting to demonstrate whether they can now tolerate peanuts.
Skolnick et al,J Allergy Clin Immunol. 2001;107(2):367-74

21. SPT to egg white provides additional diagnostic utility to serum egg white-sIgE concentration in children
Study: Retrospective analysis to determine whether the size of the SPT to egg white adds diagnostic utility for children with low egg white–sIgE.
Results: Egg OFCs passed (n = 29) and failed (n = 45)
9 (20%) failed OFCs had undetectable (<0.35 kIU/L) egg white–sIgE levels with egg SPT from 4.0 to 6.0 mm and egg/histamine SPT indices from 0.67 to 1.71
Between failed/passed OFC:
No difference in age, clinical characteristics, or egg white-sIgE
Significant differences between both egg white SPT wheal and egg/histamine SPT wheal index.
1 failed had negative SPT & sIgE -urticaria 2 hrs later during placebo phase
Knight et al, J Allergy Clin Immunol. 2006;117(4):842-7

22. Egg white SPT wheal & egg/histamine SPT wheal index
Egg white SPT wheal & egg/histamine SPT wheal index. provides additional diagnostic utility to serum egg white sIgE
Median wheal (P = .003)
Failed egg OFCs 5.0 mm
Passed egg OFCs 3.0 mm
Median egg/histamine index (P = .001)
Failed egg OFCs index of 1.00;
Passed egg OFCs index of 0.71.
50% chance of passing for egg white-sIgE levels <2.5 kUa/L, if SPT wheal of 3 mm or egg/histamine index of 0.65
Knight et al, J Allergy Clin Immunol. 2006;117(4):842-7

23. SPT Is Superior To IgE CAPRAST For The Diagnosis Of Infantile Food Allergy
Study: Infants with suspected egg and milk allergy with negative specific-IgE at the time of first visit
Results:
Egg: 72/89 (80%) suspected-HE allergies with negative IgE CAPRAST, were diagnosed as HE allergy by the elimination and provocation tests . 39 had positive egg SPT
Milk: 42/125 (33%) suspected-CM allergy infants with negative IgE were diagnosed as CM allergy, and 21 (50%) had positive milk SPT
Authors’ Conclusions: “SPT seemed to be more useful than EW- or CM- IgE CAPRAST for the diagnosis of HE or CM allergies in early infantile period.”
SPT Is Superior To IgE CAPRAST For The Diagnosis Of Infantile
Food Allergy
Ebisawa M, Ogata M, Sugizaki C, Komata T, Ikematsu K, Imai T, et al. SPT Is Superior To IgE CAPRAST For The Diagnosis Of Infantile Food Allergy. The Journal of Allergy and Clinical Immunology. 2009;123(2):S23.
Among 202 infantile cases, who had received
SPT from 2001 to 2005, 89 suspected-hen’s egg (HE) allergy and
125 suspected-CM allergy infants with negative IgE at the time of first visit
were recruited to the study. EW- and CM-specific CAPRAST were later
checked in 78 cases and 111 cases, respectively recruited to the study. EW- and CM-specific CAPRAST were later checked in 78 cases and 111 cases, respectively.
RESULTS: Among 89 suspected-HE allergies with negative IgE
CAPRAST, 72 infants were diagnosed as HE allergy by the elimination
and provocation tests Interestingly 39 infants showed positive SPT against
EW. Among 125 suspected-CM allergy infants with negative IgE, 42 cases
were diagnosed as CM allergy, and 21 infants showed positive SPTagainst
CM. In the follow up study of 78 negative EW-CAPRAST cases, 47 EWCAPRAST
out of 65 egg-allergy cases turned positive later. EWCAPRASTof
7 cases in 13 non-HE allergies also turned positive, however
EW-CAPRAST titer was relatively lower compared to that of egg allergies.
In CM allergy, IgE CAPRAST of 21 cases turned positive among 39 CM
allergy cases.
CONCLUSIONS: SPT seemed to be more useful than EW- or CM- IgE
CAPRAST for the diagnosis of HE or CM allergies in early infantile period,
and provocation test would be required for the definitive diagnosis
for suspected-HE or CM allergy infants without any proof of IgE
sensitization.
Ebisawa M et al, J Allergy Clin Immunol 2009;123(2):S23.

24. Allergy to hazelnut in adults: A two-step study
Study: 904 subjects studied for hazelnut sensitization
Results: 20 hazelnut history positive subjects ;
Prick-to-prick skin tests were positive in 13 ;
Commercial extract prick tests positive in 9;
Specific IgE to hazelnut was positive in only 3;
DBPCFC positive 7/11 subjects
Among 7 with positive DBPCFC,
6 (85.7%) had a history of hazelnut allergy
5 (71.4%) had both history and skin test positivity
BACKGROUND: Although hazelnut consumption is very high in Turkey, the prevalence of hazelnut allergy is still unknown. This study's objective was to investigate the prevalence of hazelnut sensitisation and to verify its clinical importance using double-blind, placebo-controlled challenge (DBPCFC) in an adult population. METHODS: Prick-to-prick skin tests were performed with fresh hazelnut in 904 patients admitted to the allergy department. Among the 904 subjects, 20 patients with a history of allergic reactions to hazelnut and/or positive skin tests were recalled for further evaluation. Specific IgE was measured in these subjects. Eleven (11/20) patients accepted to undergo DBPCFC with hazelnut. RESULTS: Among the 904 individuals, the history of reactions to hazelnut was positive in 16 subjects (1.8%); prick-to-prick skin tests were positive in 13 (1.4%); prick tests with the commercial product were positive in nine (0.9%); and history plus skin tests were positive in 16 (1.8%). Specific IgE to hazelnut was positive in only three patients. DBPCFC was conducted in 11 subjects with a positivity rate of 63.6% (7/11). We observed six mild and one moderate systemic reactions during the DBPCFC. Among seven subjects with a positive DBPCFC, six (85.7%) had a history of hazelnut allergy, and five (71.4%) had both history and skin test positivity. CONCLUSION: Skin test sensitisation to hazelnut was found to be 1.76% (16/904) which is similar to the sensitisation rate in previous reports. However, DBPCFC was positive in 63% of cases with a history of hazelnut allergy and/or positive skin tests in this study. These results indicate that the presence of history with a positive skin test can be suggestive of hazelnut allergy; however an oral food challenge is needed to confirm the diagnosis.
pasaoglu G, Mungan D, Misirligil Z. Allergy to hazelnut in adults: A two-step study. Allergol Immunopathol (Madr) Epub 2011/08/25.
Pasaoglu et al, . Allergol Immunopathol (Madr) Epub 2011/08/25.

25. When commercial extracts are just not good enough
Study: In 430 children with suspected food allergy-compared results obtained with SPT using commercial extracts and fresh foods, and labial and/or oral challenge
Results: egg, peanut, and cow's milk.
Cow's milk, wheal larger with commercial extracts(NS)
Conversely, wheal diameters were significantly larger with other fresh foods
SPT positive in 40% of commercial extracts and 81.3% with fresh foods.
Concordance with positive challenge & SPT: 58.8% with commercial extracts and 91.7% with fresh foods.
Results indicate that fresh foods may be more effective for detecting the sensitivity to food allergens.
The skin prick test is the most widely used test for detecting IgE-mediated food hypersensitivity. Our study aimed to define firstly the correlations between results obtained with prick tests using commercial extracts and fresh foods, and secondly the correlations between these results and those obtained with labial and/or oral challenge. We compared the wheal diameters read at 15 min with commercial extracts and fresh foods, for four foods, in 430 children with suspected food allergy. For cow's milk, wheal diameters were larger with commercial extracts, but the difference was not significant. Conversely, wheal diameters were significantly larger with fresh foods for the other food allergens. Skin prick tests were positive in 40% of cases with commercial extracts and in 81.3% with fresh foods. The overall concordance between a positive prick test and positive challenge was 58.8% with commercial extracts and 91.7% with fresh foods. These results indicate that fresh foods may be more effective for detecting the sensitivity to food allergens. Fresh foods should be used for primary testing for egg, peanut, and cow's milk sensitivity.
Rance F, Juchet A, Bremont F, Dutau G. Correlations between skin prick tests using commercial extracts and fresh foods, specific IgE, and food challenges. Allergy. 1997;52(10):
Rance et al, Allergy. 1997;52(10):

26. Diagnosing IgE-mediated hypersensitivity to sesame by an immediate-reading "contact test" with sesame oil
3 cases of immediate reaction to sesame:
42-yo man: 2 anaphylactic reactions after ingestion of breadsticks and candy,
28-yo man : 2 urticaria/angioedema reactions within 10 minutes after ingesting bread containing sesame seeds.
38-year-old man several urticaria/angioedema reactions within 30 minutes after ingesting sesame-containing foods
All 3 with negative SPT to commercial extract and none had detectable sesame-specific IgE
SPT to sesame oil and crushed sesame was negative: note oleosins are hydrophobic and can not be solubilized in saline
Alonzi J Allergy Clin Immunol 2011;127:1627-9

27. When Commercial Extracts, Prick to Prick & Serum IgE Antibody Test Fail to Diagnose The Skin “Contact Test “
An immediate-reading ‘‘contact test’’ was performed by applying on the volar side of the forearm a square of filter paper (10 x 10 mm) dipped in sesame oil and removing it after 20 minutes.
Results: Patient 2 had wheal reaction the same size as the filter paper at contact site, whereas patients 1 and 3 had several 4-mm wheals also involving the surrounding area
Immediate-reading contact test with sesame oil was negative in 10 healthy subjects & 3 pts tolerated other oil contact tests
Because Because oleosins are hydrophobic and can not
be solubilized in normal saline, a negative prick-to-prick test
with crushed sesame seeds is not sufficient to exclude sesame
allergy, especially in subjects in whom specific IgE is directed
prevalently to liposoluble proteinsand can not
prevalently to liposoluble proteins
Alonzi J Allergy Clin Immunol 2011;127:1627-9

28. Allergy Skin Test vs. In Vitro Tests What about the side effects, risks and dangers?

29. Reactions to prick and intradermal skin tests
Methods: 12-month prospective study was conducted to evaluate SRs from ST in 1,456 patients
Results:
Six patients (0.4%) had SRs during SPT. 1 reacted to aeroallergens alone, whereas the other 5 reacted to aeroallergens and food
No severe asthma, shock, hypotension, unconsciousness, or biphasic reactions occurred.
All 52 patients received epinephrine intramuscularly
Bagg A, Chacko T, Lockey R. Ann Allergy Asthma Immunol. 2009;102(5):400-2.

30. Systemic reactions to allergy skin tests
Method: Retrospective study at the Mayo Clinic to identify patients who developed systemic reactions to skin tests
Results:. 497,656 skin tests were performed : SPT 16,505 patients
6 patients experienced SRs. All had asthma.
SPT SR rate was 15 or 23 reactions per 100,000 aeroallergen tests
“It is noteworthy that there were no systemic reactions to skin tests for foods or venoms”
Conclusion: SR to skin tests was very low. SRs were mild and all patients recovered fully within 1 hour.
Valyasevi et al, Ann Allergy Asthma Immunol 1999;83:132–136.

31. Risk of adverse reactions from SPT, venipuncture, and body measurements: NHANES II 1976-80
Study: 16,204 of the U.S. population , 6 to 74 yrs, examined with routine medical procedures, including SPT & venipuncture.
SPT to 8 FDA licensed unstandardized extracts
Results:
SPT: No anaphylactic reactions after SPT were observed.
Venipuncture: One asthmatic reaction. Other AR limited to syncope, near syncope, and malaise.
Adverse reaction rates:
Venipuncture: 0.49% (95% CI, 0.38% to 0.60%);
SPT: 0.04% (95% CI, 0.01%-0.08%);
Age group 20 to 49 years had the highest occurrence of any AR to venipuncture (0.87%; 95% CI, 0.633% to 1.107%).
Turkeltaub J Allergy Clin Immunol. 1989;84(6 Pt 1):886-90

32. Allergy Skin Testing…moving into the future
Molecular Allergy: Can allergy skin tests meet the challenge?
Scarification Device
Modified-Prick Puncture
Multiplex Array
In 1930s, scarification - problem was a lack of uniformity in the abrasion AND there was the potential side effect of scarring.
Mueller device made six uniform abrasions 1-½ mm long and 15 mm apart
Pepys modified prick skin test method in 1968.
Studies comparing scarification to SPT showed increased false – and +
As a result, use of the scarification technique diminished in 1970’s .

33. Component-resolved diagnosis of pollen allergy based on SPT with profilin, polcalcin and LTP pan-allergens
Principle objective: evaluate a new diagnostic strategy - SPTs specific for 3 pan-allergens, together with an appropriate and complete panel of allergenic molecules.
Study :1329 pts with previous 2-year history of pollinosis, tested by vitro method to 13 purified allergen including pan-allergens & SPT to major allergens and pan-allergens
For SPT:
peach commercial extract adjusted to 30 mg/mL of Pru p 3, which is a LTP
date palm extract: natural profilin, Pho d 2 adjusted to 50 mg/mL & procalin
BACKGROUND: Allergy diagnosis needs to be improved in patients suffering from pollen polysensitization due to the existence of possible confounding factors in this type of patients. OBJECTIVE: To evaluate new diagnostic strategies by comparing skin responses to pan-allergens and conventional allergenic extracts with specific IgE (sIgE) to purified allergen molecules. METHODS: One thousand three hundred and twenty-nine pollen-allergic patients were diagnosed by a combination of an in vitro method with a panel of 13 purified allergens, including major allergens and pan-allergens, using a high-capacity screening technology (ADVIA-Centaur) and skin prick test (SPT) to pan-allergens and conventional extracts. RESULTS: There was a high concordance (kappa index) between in vitro (sIgE to major allergens) and in vivo (SPT to conventional extracts) methods in patients who were not sensitized to pan-allergens, but SPT with conventional extracts failed to diagnose patients with sensitization to pan-allergens. In patients who were simultaneously sensitized to polcalcins and profilins, there was a duplication both in the number of sensitizations to major allergens and in the years of disease evolution. There was a statistical association between sensitization to profilins and/or lipid transfer proteins and food allergy (P<0.0001). CONCLUSION: The novel diagnostic strategy has proven to be a valuable tool in daily clinical practice. Introduction of routine SPT to pan-allergens is a simple and feasible way of improving diagnostic efficacy. Patients sensitized to pan-allergens should be tested by an adequate panel of allergenic molecules in order to identify the allergens that are responsible for the allergic disease.

34. Component-resolved diagnosis of pollen allergy based on SPT with profilin, polcalcin and LTP pan-allergens
BACKGROUND: Allergy diagnosis needs to be improved in patients suffering from pollen polysensitization due to the existence of possible confounding factors in this type of patients. OBJECTIVE: To evaluate new diagnostic strategies by comparing skin responses to pan-allergens and conventional allergenic extracts with specific IgE (sIgE) to purified allergen molecules. METHODS: One thousand three hundred and twenty-nine pollen-allergic patients were diagnosed by a combination of an in vitro method with a panel of 13 purified allergens, including major allergens and pan-allergens, using a high-capacity screening technology (ADVIA-Centaur) and skin prick test (SPT) to pan-allergens and conventional extracts. RESULTS: There was a high concordance (kappa index) between in vitro (sIgE to major allergens) and in vivo (SPT to conventional extracts) methods in patients who were not sensitized to pan-allergens, but SPT with conventional extracts failed to diagnose patients with sensitization to pan-allergens. In patients who were simultaneously sensitized to polcalcins and profilins, there was a duplication both in the number of sensitizations to major allergens and in the years of disease evolution. There was a statistical association between sensitization to profilins and/or lipid transfer proteins and food allergy (P<0.0001). CONCLUSION: The novel diagnostic strategy has proven to be a valuable tool in daily clinical practice. Introduction of routine SPT to pan-allergens is a simple and feasible way of improving diagnostic efficacy. Patients sensitized to pan-allergens should be tested by an adequate panel of allergenic molecules in order to identify the allergens that are responsible for the allergic disease.

35. Concordance of SPT extracts and sIgE to the corresponding pan-allergens
Results:
Concordance of SPT extracts and sIgE evaluated: high diagnostic value is observed for
Profilin SPT (positive and negative concordance 82.3% and 90.8%, respectively)
LTP-enriched SPT (positive and negative concordance 65% and 94.3% respectively ),
Polcalcin SPT performance lower (positive and negative concordance 50% and 90.4% respectively).
Authors’ conclusion: “ Novel diagnostic strategy has proven to be a valuable tool in daily clinical practice. Introduction of routine SPT to pan-allergens is a simple and feasible way of improving diagnostic efficacy.”
Barber et al,Clin Exp Allergy 2009;39:

36. Why Skin Testing is Superior to In Vivo Testing Because:
More cost and time efficient for patient
Results available on initial consultation allowed for development of specific treatment plan
Predictive value in terms of presence of clinical allergy and possible severity
In some cases greater predictive value than in vivo test
Ability to test to allergens that may be altered in extract preparation process e.g., natural foods
Can also be used in component-resolved diagnosis