Skin prick test results, reaction severity indicate risks for sesame allergy persistence
Key takeaways:
- Patients with a reaction of grade 2 or higher were 19.9 times more likely to develop persistent allergy.
- Patients with an SPT higher than 6.7 mm were 3.08 times more likely to develop persistent allergy.
Reaction severity and skin prick testing results predicted persistent sesame allergy among children, according to a study published in Pediatric Allergy and Immunology.
These risk factors can help physicians develop management strategies and select candidates for oral immunotherapy, Alp Kazancioglu, MD, fellow, pediatric allergy and immunology division, faculty of medicine, Hacettepe University, Ankara, Turkey, and colleagues wrote.
“Sesame and its derivatives are commonly consumed in our population and the Middle East and are regarded as significant food allergens,” Kazancioglu told Healio.
Also, Kazancioglu said, the prevalence of sesame allergy has been rising around the world, especially in the United States, influenced by consumption habits and ethnicity.
“Limited data indicated that sesame allergy displays a relative persistence similar to that of tree nuts and peanuts,” he said. “Thus, we focused on the persistence of sesame allergy and its associated risk factors.”
The retrospective longitudinal study included 84 children (72.6% boys) with a sesame allergy diagnosis treated in the pediatric allergy department at Hacettepe University Ihsan Dogramaci Children’s Hospital.
The cohort included 32 children (38%) assessed for sesame allergy after developing early onset atopic dermatitis, 40 children (48%) assessed after an allergic reaction to sesame, and 12 children (14%) assessed during evaluation for other food allergies.
Also, 60 children (71.4%) had another food allergy, most often tree nuts (n = 48; 57.1%) and seeds such as poppy, sunflower, pumpkin and mustard (n = 21; 25%). Comorbidities included previous diagnosis of atopic dermatitis (n = 69; 82.1%), current asthma (n = 48; 57.1%) and current allergic rhinitis (n = 37; 44%).
Follow-up times ranged from 24 to 208 months with a median of 56.5 months. The median age at the final visit was 65 months.
With a median of three episodes each, every child in the cohort had a documented allergic reaction related to sesame, with 39 children (46.4%) experiencing at least one episode of anaphylaxis and 35 (41.6%) experiencing at least one positive oral food challenge.
Among 60 children who sought medical care for their first reaction, tahini caused 83.3% of the cases and sesame seeds caused 16.6% of the cases.
The most common reactions were skin and mucosal (85%), gastrointestinal (31.7%) and respiratory (11.6%). Also, 53.3% were grade 1, 33.3% were grade 2, 11.7% were grade 3 and 1.7% were grade 5.
At diagnosis, median age was 10 months, median SPT wheal diameter with commercial sesame extract was 6 mm, and median sesame-specific IgE was 5.6 kUA/L.
Median ages of first reactions included 12 months for those diagnosed after an allergic reaction to sesame, which the researchers called significantly younger than the 36 months for those children diagnosed after assessment following development of early atopic dermatitis, and 36 months for those diagnosed after assessment for other food allergies.
“The proportion of persistence was found to be higher than previously reported in the literature,” Kazancioglu said.
At a median follow-up time of 56.5 months, 69 children (82.1%) exhibited persistent sesame allergy, and 15 (17.8%) had developed natural tolerance, with negative OFC results.
The children with persistent sesame allergy included 19 with a positive OFC and 50 with a consistent history of IgE-mediated allergic reactions to sesame during the final year of follow-up.
The most recent reactions included grade 1 (50.7%), grade 2 (27.5%), grade 3 (15.9%) and grade 4 (5.8%). The follow-up period also included reactions confirmed by a physician to be grade 2 or higher for 49 of 84 patients (58.3%).
Prevalence of persistent sesame allergy in the diagnostic subgroups, including 90.6% for those with atopic dermatitis, 77.5% for those with reactions and 75% for those assessed for other food allergies, was not significantly different, the researchers said.
Rates of severe reactions of grade 2 or higher during the follow-up period included 63.7% for the children with persistent sesame allergy and 33.3% for those whose allergy had resolved (P = 0.03).
“The severity of the first reaction and skin prick test results were identified as independent risk factors for persistence,” Kazancioglu said. “The higher persistence observed, surpassing that documented in the literature, is attributable to our status as a tertiary allergy center, where we typically manage severe food allergies.”
During the first reaction, SPT results with commercial sesame extract included 8.2 mm for the children with persistent sesame allergy and 6 mm for those whose allergy had resolved (P = .001). Similarly, SPT results with tahini included 10 mm for those with persistent sesame allergy and 7.5 for those whose allergy had resolved (P = .032).
“Skin prick test results were found to be strong predictors. However, surprisingly, specific IgE levels did not represent an independent risk factor,” Kazancioglu said. “It has been previously reported that specific IgE levels have predictive value for the persistence of peanut allergies.”
Median sesame-specific IgE levels during the first reaction included 6.2 kUA/L for the children with persistent sesame allergy and 1.5 kUA/L for those whose allergy had resolved (P = .009).
Multivariate analysis indicated that the risk for persistent sesame allergy increased by a factor of 19.9 (95% CI, 1.37-289.13) with a severe reaction of grade 2 or higher. Also, each 1 mm increase in SPT wheals with commercial sesame extract at the first reaction increased risk for persistent sesame allergy by a factor of 1.7 (95% CI, 1.05-3.04).
In a proportional hazards regression model, patients with SPT results with commercial sesame extract of 6.7 mm or higher at the first reaction were 3.08 times (95% CI, 1.17-8.12) more likely to develop persistent sesame allergy than those whose results were less than 6.7 mm.
Median changes in SPT results with commercial sesame extract included a 0.8 mm increase for children with persistent sesame allergy and a 3 mm decrease for the children whose allergy had resolved, which the researchers called a significant decrease.
Additionally, the researchers said, 63% of the children whose SPT results fell (n = 38) and 93% of those whose SPT results did not change (n = 3) or whose results increased (n = 12) remained allergic to sesame.
Sesame-specific IgE significantly fell (P < .05) from the first reaction to the final visit for the children whose allergy resolved, but there was no significant change for the children whose sesame allergy persisted.
“Our findings indicate that increased sensitization levels are stronger markers for predicting persistent sesame allergy, whereas decreased levels have limited predictive value for tolerance development,” Kazancioglu said.
The 28 children whose sesame-specific IgE fell from the first reaction to the final visit included 61% whose sesame allergy persisted. Among the two children whose levels did not change and the 19 whose levels increased, 95% of their allergies persisted.
Median SPT results with both commercial sesame extract and tahini and median levels of sesame-specific IgE, sesame-specific IgE/total IgE ratio, and Ses i 1 specific IgE all were significantly higher for the children with persistent sesame allergy than those whose allergy had resolved at the final visit.
Based on an analysis of receiver operating characteristic curves, the researchers said that SPT wheal size for commercial sesame extract and tahini (P < .001) and sesame-specific IgE levels (P < .001) were significant predictors of persistent allergy.
Optimal cutoff values for persistence included 5.7 mm for commercial sesame extract SPT (area under the curve [AUC] = 0.93; 95% CI, 0.86-0.99; sensitivity = 79.3%; specificity = 91.7%) and 6.7 mm for tahini SPT (AUC = 0.92; 95% CI, 0.84-1; sensitivity = 94.5%; specificity = 84.3%).
The optimal cutoff value for sesame-specific IgE was 2.1 kUA/L (AUC = 0.84; 95% CI, 0.72-0.96; sensitivity = 82.8%; specificity = 75%).
Based on these findings, the researchers concluded that reaction severity and SPT results in the first reaction were independent risk factors for persistent sesame allergy. Also, increased sensitization levels were better predictors of persistence than decreasing levels were in predicting resolution.
“Utilizing predictive risk factors for persistent sesame allergy can facilitate the selection of candidates for early oral immunotherapy, which can ultimately enhance the quality of life of patients and their parents,” Kazancioglu said.
For more information:
Alp Kazancioglu, MD, can be reached at alpkazancioglu@gmail.com.
Perspective
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These findings are not too surprising. One thing we know from lots of studies with food allergy is that the larger the skin test size and the higher the specific IgE to the food, the more likely someone is truly allergic (ie, if you feed everyone the food, the larger the skin test and the higher the IgE, the more likely they will react).
These markers have also been shown in some studies to correlate with persistence of food allergies, which is what this study shows as well. Whether these are identifying a different phenotype is not known. The same goes for patients with a history of more severe reactions.
However, I would have a tough time correlating these data to my own practice for various reasons. I don’t use tahini for skin testing, I likely use a different device for skin testing, which may give different results, and I don’t see as much sesame allergy as some places do, such as Turkey.
It’s easy to reflexively say that when we see a kid with a large skin test or high serum IgE to a food, we may instinctively say “that’s a worse allergy” or “that kid is less likely to outgrow the allergy.” But in reality, I try not to do that in my practice, because these tests are not accurate enough to truly predict that.
As the authors suggest, if you can predict who is going to “outgrow” an allergy, you can make better decisions about whom to direct therapy to. If a patient is likely to outgrow the allergy, it probably makes less sense to aggressively treat the allergy. Unfortunately, though, the predictive ability is not high enough here (or in other studies) to accurately predict who outgrows allergy with enough certainty.
Ideally, large studies, where every patient gets a baseline challenge and then is challenged every year in the clinical setting, is the best way to allow for identification of biomarkers or traits that may predict who outgrows the allergy.
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