Real‐World Impact on Dietary Intake and Quality of Life Post‐Successful Oral Food Challenge to Peanut and Tree Nuts

Oral food challenge (OFC) is considered the gold standard to confirm resolution of food allergies, but it is a resource intensive and potentially risky procedure [1]. Patients who attain a tolerant OFC outcome are able to safely incorporate the food into their diet [2] and are encouraged to do so because re-sensitisation could occur with prolonged secondary avoidance [3]. Recent studies report a significant proportion of patients discontinue ingestion of the food allergen post-tolerant OFC outcome [4], with tree nuts in particular having a much lower continuation rate compared to other food allergens [5, 6]. We aimed to evaluate clinical and demographic factors affecting patients' ingestion of challenged food allergen and their food allergy related quality of life (QoL) after completion of a peanut or tree nut OFC. In this prospective observational cohort study, we recruited children (under 13 years old) who had completed an OFC to peanut, tree nut or combination of nuts (mixed nut) at Starship Children's Hospital Auckland, New Zealand, between 1 January 2017 and 31 December 2020. We sent consenting parents/caregivers three electronic questionnaires through REDCap (Research Electronic Data Capture) online platform that was also used to collect and securely store study data [7]. The first questionnaire included questions relating to ingestion habits of challenged food allergen. We considered those self-reporting ‘still ingesting the challenged food at time of completing questionnaire’, including ingestion frequencies ranging from more than once a week to less than once a month, as ‘having ongoing ingestion’. In the case of participants who were challenged to multiple nuts, we considered those having discontinued ingestion of one or more of the challenged nuts as having ‘discontinued ingestion’. The other questionnaires were the validated food allergy-related quality of life questionnaire (FAQLQ) [8] and one adapted from a New Zealand-oriented Socioeconomic Position Index questionnaire [9]. Analyses were by complete case approach. For FAQLQ, an average score was calculated for each participant with a lower score indicating better QoL. Fisher's exact test was carried out for categorical variables. T-test was conducted for continuous variables presented as mean with standard deviation (SD) and rank-sum test was conducted if non-parametric. Statistical significance was defined as a p value of < 0.05. Analyses were done using STATA 15.0. The study protocol was pre-registered with institutional research office and the study was granted institutional (A+ 9157) and human ethics committee (AHREC AH22174) approvals. A total of 261 eligible participants were contacted for recruitment and 104 completed responses were received during the 5-month (June–November 2021) period the study was open. The mean participant age at the time of OFC was 4.8 years (SD 3.1 years) with 53% male. Mean follow-up time from OFC was 24.3 months (SD 12.7 months). Participants were ethnically diverse and included 59% European/Other, 30% Asian, 7% Māori and 5% Pacific. Of total participants, 74% attained tolerant food-challenge outcome, 25% reacted, and 1% had an equivocal challenge. Of the 76 participants (excluding one with missing records) who attained tolerant food-challenge outcome, 78% reported ongoing ingestion of challenged food allergen. Participants were more likely to continue ingestion following attaining a tolerant peanut challenge outcome (31/35, 89%) compared to tolerant tree nut outcome (28/40, 70%) (p = 0.050). The peanut ingestion habits of families were not associated with ongoing participants' peanut continued ingestion habits (Fisher's exact test p = 1.000, Table 1). In contrast, participants who attained tolerant tree nut outcome were more likely to continue ingestion of the tree nut if their family usually consumed the same tree nut as part of their diet (Fisher's exact test p = 0.022). Gender, age and time interval since OFC did not affect likelihood of ongoing ingestion. The majority of participants who discontinued either peanut or tree nut intake did so within 1 month of OFC (29% within 1 week and 35% 1–4 weeks post OFC). For peanut, 25% of participants discontinued within 1 week and 75% discontinued at 1–4 weeks of OFC. For tree nuts, 50% of participants discontinued 1 month or more post OFC. There was no significant difference in FAQLQ score between patients who attained tolerant food challenge outcome [median = 0.962, interquartile range (IQR) = 0.333, 2.231] and those who reacted during OFC (median = 0.750, IQR = 0.250, 1.367) (p = 0.561). However, continued ingestion of the food post attaining tolerant food-challenge outcome was associated with a significantly better age- and gender-adjusted FAQLQ score (ingestion group, median = 0.583, IQR = 0.115, 1.667 vs. discontinued ingestion group, median = 1.917, IQR = 1.385, 3.400; p = 0.001). To summarise, in this New Zealand-based study examining real-world peanut and tree nut ingestion habits and QoL post-OFC procedure, we found that attaining tolerant food-challenge outcome did not guarantee sustained changes in ingestion habits, particularly for tree nuts. We found that family's dietary habits have a significant effect on continuation of tree nut ingestion following tolerant food-challenge outcome but found no such association for patients challenged to peanuts. Additionally, we found that the outcome of the OFC did not affect QoL scores, but more importantly, continued ingestion of challenged food allergen had a significant positive impact on QoL. Our study's strengths include an ethnically diverse cohort and inclusion of a broad range of tree nuts. Limitations include a lack of longitudinal QoL evaluation and for any potential interactions between clinical history relating to the challenged allergen and post-OFC outcomes. To conclude, this study highlights the value of pre-procedural counselling and post-OFC support for patients' ongoing ingestion of peanut and tree nuts to positively influence their dietary intake and quality of life. Jerry Shen was involved in visualization, methodology, investigation, data curation, project administration and writing – original draft. Dug Yeo Han was involved in validation and writing – review and editing. Kuang-Chih Hsiao was involved in supervision, conceptualization, methodology, data curation, formal analysis, writing – review and editing. We thank Dr. Maia Brewerton for her critical review of the study proposal and Dr. Annaliesse Blincoe and Ms. Jenny Heyward for their clinical insights and scientific advisory. Open access publishing facilitated by The University of Auckland, as part of the Wiley - The University of Auckland agreement via the Council of Australian University Librarians. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.