Accidental allergic reactions in food allergy: Causes related to products and patient's management

To the Editor, Whilst European labelling regulations require food manufacturers and providers to list 14 common allergens in prepackaged and non– prepackaged foods (eg, food service), products may contain undeclared allergens. Allergens can accidentally end up in food during the production process as a result of cross‐contamination. The unintentional presence of allergens in food is a serious concern for people with food allergies. Cross‐contamination is not covered by labelling regulations, although food producers often use precautionary statements. Despite all measures, ingestion resulting in accidental reactions still occurs and can be severe and even fatal. Therefore, we evaluated frequency, causes, severity and consequences in terms of medical treatment of accidental allergic reactions in adults with a physician‐diagnosed food allergy confirmed by convincing history and sensitization. A prospective study with 1‐year follow‐up was carried out in adults (n = 157) with a mean of 3.5 (SD 2.1) confirmed food allergies. Response rate was 65%. Most patients had a combination of primary and pollen‐related food allergy (Table 1). All patients received dietary advice per food allergen by the physician or dietitian based on the patient's history and observations during oral food challenges. Patients were asked to report all accidental reactions online to obtain data about causes, severity, medical treatment and sick leave. Reactions with local oral allergy symptoms were classified as being mild, reactions with symptoms from skin and mucous membranes and/or gastrointestinal tract were classified as moderate, and reactions with respiratory symptoms and/or cardiovascular symptoms were classified as being severe. Each reaction and submitted label were reviewed within 1 week by the multidisciplinary research team to determine whether the reaction was compatible with a food allergic reaction and the food allergy of the patient. (see Data S1‐method section in detail). A total of 153 reactions were reported by 73 of 157 patients (46%), whereas 84 (54%) of the patients did not report any accidental reaction in the 1‐year follow‐up. From the patients that reacted, 41 (26%) reported 1 reaction and 32 (20%) ≥2 reactions (range 2‐11). Of those who reacted, the mean number of accidental reactions was 2.10 (SD 2.0) per person per year. Patients who reported reactions were significantly more often women, had a significantly longer duration of food allergy and had significantly more often a confirmed allergy for peanut, sesame and vegetables compared with patients who did not report reactions. Of the reactions, 62 (41%) were due to prepackaged foods, 37 (24%) were during a meal outside the home, 30 (20%) were due to fresh products, 13 (9%) were due to products or meals in a foreign country, and 11 (7%) occurred whilst having a meal at home. A total of 52 labels of prepackaged products or composite meals were received. Related to the specific food allergy profile of individual patients, in 19 of these 52 reactions (37%), the suspected allergen(s) were not mentioned as ingredient or warning on the label. Patients read the label in n = 36 (69%). Reasons for not reading the label were as follows: label was illegible (n = 3), consumed the food before (n = 3) and other reasons such as “I didn't expect allergens in the product”/“thought that it was safe” (n = 10). Thirty‐seven reactions (24%) were caused by composite meals outside the home: 68% in restaurants, followed by 22% at friends’ or relative's home and 11% at other places (eg, camp and exhibition). Patients had called the restaurant before visiting or informed the cook, chef or waiter in 26 reactions (70%) or carefully checked the menu in 5 reactions (14%) or assumed it was safe in 6 reactions (16%). A wide range of food products were responsible for causing accidental reactions. Products could have up to four culprit allergens present that were not mentioned on the label or were undeclared in non–prepackaged foods. Severity of accidental reactions was mild in 33 (22%), moderate in 77 (50%) and severe in 43 (28%), of which 9 with cardiovascular involvement. In 103 (67%) reactions, patients used medication for treatment of the reaction; number and types of medication use increased with severity of the reaction. No medication was used in 19 (58%) of the mild reaction, 25 (32%) of the moderate reactions and 6 (14%) of severe reactions. In eight reactions, medical care was sought. (Table 2). We showed that the mean number of accidental reactions was approximately 1 per person per year. Other studies have also reported frequencies of accidental reactions, but comparability is limited due to difference in age group (children vs adults), time frame and food allergens. For example, Anibarro et al reported 1.98 (range 1‐10) reactions over a 5‐year period. Kanny et al reported a mean of 4.7 (SD 5.6), 53% had 2 or more reactions, but the time frame within which these reactions occurred was not further specified, and