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Background: The 2014 estimates of prevalence of food allergy (FA) in Europe published by the European Academy of Allergy and Clinical Immunology included only the eight so‐called big foods (cow's milk/egg/wheat/soy/peanut/tree nuts/fish/shellfish). Those estimates have recently been updated. Complementing this, we sought to identify and estimate the prevalence of allergy to other foods that have been reported during the last decade. Methods: Six databases were searched for studies published 2012–2021. Random‐effects meta‐analysis was performed to derive pooled prevalence of allergy to each food. Results: Twenty‐seven studies were included, containing a total of 66 FAs. Among the most frequently reported FAs, the lifetime and point prevalence range of self‐reported kiwi allergy was 0.1%–1.0% and 0.2%–8.1%, respectively, while the food challenge (FC)‐verified kiwi allergy point prevalence range was 0.01%–0.10%. The point prevalence range for self‐reported peach allergy was 0.2%–3.2%, while the range for FC‐verified peach allergy was 0.02%–0.05%. The lifetime and point prevalence range for self‐reported tomato allergy was 0.01%–1.8% and 0.2%–2.1%, respectively. Conclusion: Allergy to some foods traditionally not considered important are now emerging as relevant FAs. The focus on FA in Europe should not be limited to the so‐called eight big FA, but extended to other types of foods which need to be considered both for clinical purposes and population risk assessment. [ABSTRACT FROM AUTHOR]

In 2014, the European Academy of Allergy and Clinical Immunology (EAACI) published the first systematic review that summarized the prevalence of food allergy (FA) and food sensitization in Europe for studies published 2000–2012. However, only summary estimates for tree nut allergy (TNA) were feasible in that work. In the current update of that systematic review, we summarized the prevalence of tree nut allergy/sensitization to individual tree nuts. Six databases were searched for relevant papers published 2012–2021 and 17 eligible studies were added to the 15 studies already identified between 2000 and 2012, giving a total of 32 studies. Of the investigated tree nuts, meta‐analysis was possible for hazelnut, walnut, almond, and in few cases, for cashew, and Brazil nut. The lifetime self‐reported prevalence was 0.8% (95% CI 0.5–1.1) for hazelnut and 0.4% (0.2–0.9) for walnut. The point self‐reported prevalence was 4.0% (2.9–5.2) for hazelnut, 3.4% (2.0–4.9) for Brazil nut, 2.0% (1.1–2.9) for almond, and 1.8% (1.1–2.5) for walnut. Point prevalence of food challenge‐confirmed TNA was 0.04% (0.0–0.1) for hazelnut and 0.02% (0.01–0.1) for walnut. Due to paucity of data, we could not identify any meaningful and consistent differences across age groups and European regions. [ABSTRACT FROM AUTHOR]

In 2014, the European Academy of Allergy and Clinical Immunology published prevalence estimates for food allergy (FA) and food sensitization (FS) to the so‐called eight big food allergens (i.e. cow's milk, egg, wheat, soy, peanut, tree nuts, fish and shellfish) in Europe for studies published between 2000 and 2012. The current work provides 10‐year updated prevalence estimates for these food allergens. A protocol was registered on PROSPERO before starting the research (reference number CRD42021266657). Six databases were searched for studies published 2012–2021, added to studies published up to 2012, resulting in a total of 93 studies. Most studies were graded as at moderate risk of bias. The overall pooled estimates for all age groups of self‐reported lifetime prevalence were as follows: cow's milk (5.7%, 95% confidence interval 4.4–6.9), egg (2.4%, 1.8–3.0), wheat (1.6%, 0.9–2.3), soy (0.5%, 0.3–0.7), peanut (1.5%, 1.0–2.1), tree nuts (0.9%, 0.6–1.2), fish (1.4%, 0.8–2.0) and shellfish (0.4%, 0.3–0.6). The point prevalence of food challenge‐verified allergy were as follows: cow's milk (0.3%, 0.1–0.5), egg (0.8%, 0.5–1.2), wheat (0.1%, 0.01–0.2), soy (0.3%, 0.1–0.4), peanut (0.1%, 0.0–0.2), tree nuts (0.04%, 0.02–0.1), fish (0.02%, 0.0–0.1) and shellfish (0.1%, 0.0–0.2). With some exceptions, the prevalence of allergy to common foods did not substantially change during the last decade; variations by European regions were observed. [ABSTRACT FROM AUTHOR]

Following the "hygiene hypothesis" and the increase in the prevalence of atopic diseases such as allergic rhinitis, a plethora of studies have investigated the role of sibship composition as a protective factor, but findings are conflicting. The aim of this study was to synthesize the global literature linking birth order and sibship size (number of siblings) to the risk of allergic rhinitis. Fifteen databases were systematically searched, with no restrictions on publication date or language. Observational studies with defined sibship composition (birth order or sibship size) as exposure and allergic rhinitis or allergic rhinoconjunctivitis (self‐reported or clinically diagnosed) as outcome were eligible. Study selection, data extraction, and quality assessment were performed independently in pairs. Relevant data were summarized in tables. Comparable numerical data were analyzed using meta‐analysis with robust variance estimation (RVE). Seventy‐six reports with >2 million subjects were identified. Being second‐ or later‐born child was associated with protection against both current (pooled risk ratio [RR] 0.79, 95% CI 0.73–0.86) and ever (RR 0.77, 95% CI 0.68–0.88) allergic rhinitis. Having siblings, regardless of birth order, was associated with a decreased risk of current allergic rhinitis (RR 0.89, 95% CI 0.83–0.95) and allergic rhinoconjunctivitis (RR 0.92, 95% CI 0.86–0.98). These effects were unchanged across age, time period, and geographical regions. Our findings thus indicate that primarily, a higher birth order, and to a lesser extent the number of siblings, is associated with a lower risk of developing allergic rhinitis. [ABSTRACT FROM AUTHOR]

Background: Atopic dermatitis and food allergy are two frequently concomitant manifestations of the presence of atopy. A substantial number of studies have been published on the association of birth order and sibship size (number of siblings) with atopic dermatitis, food allergy, and atopy. The present work is the first systematic synthesis of the existing literature on this topic. Methods: Fifteen databases were searched. Screening, data extraction, and quality assessment were performed by independent pairs. Comparable numerical data were statistically synthesized using random‐effects robust variance estimation. Results: In total, 114 studies were included out of 8819 papers obtained from database searches. Birth order ≥2 versus 1 was associated with lower risk of ever atopic dermatitis (pooled risk ratio [RR] 0.91, 95% CI 0.84–0.98), current food allergy (RR 0.77, 95% CI 0.66–0.90), and positive skin prick test (SPT) to common aeroallergens (RR 0.86, 95% CI 0.77–0.97). Sibship size ≥2 versus 1 was associated with decreased risk of current atopic dermatitis (RR 0.90, 95% CI 0.83–0.98), ever atopic dermatitis (RR 0.92, 95% CI 0.86–0.97), and positive SPT to common aeroallergens (RR 0.88, 95% CI 0.83–0.92). No putative associations were seen regarding atopy assessed through allergen‐specific immunoglobulin E with common allergens. Conclusion: The presence of siblings and being second‐born or later may decrease the lifetime risk of atopic dermatitis and food allergy, albeit marginally. Similar association was seen with SPT sensitization. However, significant protection was not found for IgE sensitization. [ABSTRACT FROM AUTHOR]

Food allergy (FA) is increasingly reported in Europe, however, the latest prevalence estimates were based on studies published a decade ago. The present work provides the most updated estimates of the prevalence and trends of FA in Europe. Databases were searched for studies published between 2012 and 2021, added to studies published up to 2012. In total, 110 studies were included in this update. Most studies were graded as moderate risk of bias. Pooled lifetime and point prevalence of self‐reported FA were 19.9% (95% CI 16.6–23.3) and 13.1% (95% CI 11.3–14.8), respectively. The point prevalence of sensitization based on specific IgE (slgE) was 16.6% (95% CI 12.3–20.8), skin prick test (SPT) 5.7% (95% CI 3.9–7.4), and positive food challenge 0.8% (95% CI 0.5–0.9). While lifetime prevalence of self‐reported FA and food challenge positivity only slightly changed, the point prevalence of self‐reported FA, sIgE and SPT positivity increased from previous estimates. This may reflect a real increase, increased awareness, increased number of foods assessed, or increased number of studies from countries with less data in the first review. Future studies require rigorous designs and implementation of standardized methodology in diagnosing FA, including use of double‐blinded placebo‐controlled food challenge to minimize potential biases. [ABSTRACT FROM AUTHOR]

Background: Recent reports indicate that the prevalence of food allergy is increasing, but accurate estimates remain a challenge due to cross‐reactivity and limited use of precise diagnostic methods. Molecular allergy diagnostics, in which sensitization to individual molecular allergens is measured, is emerging as a promising tool for evaluation of sensitization profiles. In this systematic review, we summarized estimates of prevalence of sensitization to molecular food allergens in the general population in Europe. Methods: Following a protocol prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO; reference CRD42021266657), we searched seven databases with no restrictions on publication date or language. Two reviewers independently screened the literature, extracted data, and appraised the risk of bias in the included studies. The findings were synthesized narratively. Results: From 4776 de‐duplicated records, five studies, with low to moderate overall risk of bias, were included. Forty‐six molecular allergens from 18 foods were investigated. Overall, the prevalence of sensitization was low, particularly for major allergens, and non‐existent for 10 molecular allergens (0% [95% CI 0–0.8]). The highest prevalence was seen for PR‐10 proteins, such as Cor a 1.04 (13.6% [95% CI 10.9–16.9]). Conclusions: Available data, primarily from North‐western Europe, indicate that sensitization to molecular food allergens is overall low. The highest estimates were found for cross‐reactive PR‐10 proteins. There were not enough studies to discern regional differences or perform meta‐analysis, highlighting the need for more population‐representative studies in order to elucidate patterns of sensitization to molecular food allergens in Europe. [ABSTRACT FROM AUTHOR]

Introduction: The hygiene hypothesis suggests that reduced exposure to microbes might have contributed to the increase in prevalence and incidence of asthma and allergy observed during the second half of the last century. Following this proposal, several studies have investigated the role of sibship size and birth order in the development of asthma and allergic diseases, but the underlying evidence is conflicting. The objective of the present systematic review will be to identify, critically appraise and synthesise previous primary studies investigating the association of sibship size and birth order with the risk of asthma and allergic diseases., Methods and Analysis: The following databases will be searched: AMED, CABI, CINAHL, Embase, Google Scholar, OAIster, Open Access Theses and Dissertations, Open Grey, ProQuest Dissertations & Theses Global, PsycINFO, PubMed, SciELO, Scopus, Web of Science and WHO Global Index Medicus. Studies published up until 31 December 2020 will be eligible. There will be no restrictions by language and geographical location. Risk of bias in the included studies will be assessed using the Effective Public Health Practice Project quality assessment tool. The produced evidence will be synthesised narratively, and studies that present comparable numerical data will be included in meta-analyses using random effects model., Ethics and Dissemination: Only data from the published literature will be included in this systematic review. Therefore, no ethical approval is required. The final review paper will be published in a peer-reviewed journal., Prospero Registration Number: CRD42020207905., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)