Clinical letter

Background : Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the main causes of hypersensitivity to drugs in the paediatric population. Studies about the natural history of cross-intolerance reactions to NSAIDs are scarce. The aim of this study was to assess cross intolerance to NSAIDs over time in the paediatric population. Methods : Retrospective study in patients under 18 years old diagnosed with cross intolerance to NSAIDs by oral challenge test between 1999 and 2019. These patients were prospectively re-assessed in 2021-2022 by challenge with acetylsalicylic acid (ASA). Patient characteristics and potential factors that might have helped them develop tolerance to NSAIDs were analysed. Results : Between 1999 and 2019, 46 patients were diagnosed with cross intolerance to NSAIDs; of these, 19 were re-assessed at a second visit after a mean of 116 months from initial diagnosis. The NSAID most involved in reactions was ibuprofen. At Visit 2, it was observed that 15 (78.9%) patients tolerated ASA and other NSAIDs. Patients with atopy and who initially presented with asthma were more likely to maintain their diagnosis of cross intolerance to NSAIDs ( p=0.001 and p=0.035, respectively). On the contrary, most patients with initial angioedema developed tolerance over time ( p=0.035). Conclusion : Patients with cross intolerance to NSAIDs may develop tolerance to them over time. This tolerance might be determined both by the presence of atopy and the initial history of the patient.

Background: Cow’s milk allergy can result in anaphylactic reactions. The estimated prevalence of cow’s milk allergy in developed countries ranges from 0.5% to 3% at age 1 year. Objective: Our objective was to perform a systematic review and, if possible, a meta-analysis to assess the frequency of fatal and recurrent anaphylaxis induced by cow’s milk. Methods: We searched PubMed/MEDLINE, EMBASE, and the Web of Science for studies that had assessed fatal and recurrent anaphylaxis induced by cow’s milk for the population of a country or at least an administrative region. Our review included cohort, cross-sectional, and registry studies that had assessed the incidence or prevalence of recurrent anaphylaxis or the incidence of fatal anaphylaxis due to cow’s milk. Results: The pooled prevalence of recurrence (PR) for at least an episode of anaphylaxis was 26.98% (3.41-155.19). Teymourpour et al (Iran) reported the highest PR (53.10%); the 2 studies with the lowest PR were from France (5.16 and 0.42 respectively) (p<0.01). Nine studies on fatal anaphylaxis were selected (41 deaths) and found to be highly heterogeneous (I 2=75.91%). Levy et al and Bassagio et al reported the highest incidence rate (IR 0.15 and 0.6 deaths per million persons-year). Conclusion: The PR of anaphylaxis was approximately one quarter of patients with anaphylaxis due to cow’s milk, while deaths from anaphylaxis caused by cow’s milk were very rare, although some studies report rates as high as 15 times the lowest IR.