Background: Cashew nut allergy is becoming common, but the risk of severe reactions in comparison with peanut allergy is unknown.
Method: A case-matching study of children with a recent history of a reaction after definite nut ingestion, with positive skin prick test. Children whose worst ever reaction was to cashew nut (cashew group), were matched with two children each whose worst ever reaction was to peanut (peanut group) for sex, age of reaction and presentation, amount ingested, and asthma. Severity of the worst clinical reactions to date was compared.
Results: A total of 47 children in the cashew group were matched to 94 in the peanut group. There were no differences in clinical features between groups for matching criteria, except asthma (more prevalent in the peanut group). Wheezing and cardiovascular symptoms were reported more frequently during reactions in the cashew compared with the peanut group: odds ratios (OR) 8.4 (95% CI: 3.2-22.0) and 13.6 (95% CI: 5.6-32.8), respectively. The cashew group received intramuscular adrenaline more frequently: OR 13.3 (95% CI: 5.5-32.2). Overall, the OR for a severe reaction (severe dyspnoea and/or collapse) in the cashew group was 25.1 (95% CI: 3.1-203.5).
Conclusions: Previous studies show cashew nut can cause severe reactions; this is the first study to show by case-matching that severe clinical reactions occur more frequently in cashew compared with peanut allergy. The nut type which caused the worst reaction to date should be considered when providing emergency medication.