No abstract

No abstract

No abstract

No abstract

To the Editor, Some patients with anaphylaxis experience recurrences even when a trigger is identified in the initial reaction. [1][2][3][4][5][6] However, recurrence has received less attention than other epidemiological parameters associated with this condition. [1][2][3][4][5][6] We carried out a systematic review of the international literature to investigate the frequency, severity, and time to onset of recurrence.Details of the methodology of the review are provided in the additional material.After ruling out 3,527 articles, we eventually selected 35 for quantitative analysis (Figure A1).The 35 studies on recurrence covered 34,864 patients. The median percentage of recurrence was 27% (IQR, 12.8-61.43) (Table A1, A2). The median duration of studies was 5 years (range, 1-13 years).Retrospective and prospective cohorts accounted for only 31.43%(Table 1 and Table A2).Studies from Australia reported the highest rates (up to 57.27 recurrences per 100 person-years) (Figure 1, Table A3), with prevalence values higher than 50% for at least 1 recurrence. 3,4 For both prevalence and incidence, differences between continents were statistically significant (p < .01) and heterogeneity was high (I 2 > 99%).Studies carried out in 2 age groups (under 19 years and all ages) did not reveal differences for incidence or prevalence of recurrence rates (p = .88 and .67, respectively) (Table A3), although differences may be diluted because of the inclusion of children and adolescents in the studies covering all age groups. We found no studies that provided data on all causes of recurrence for the >18-year-old group.Given that the review revealed up to 25 different ways of grouping ages, it was impossible to aggregate them into more homogeneous categories.By principal cause of anaphylaxis, the lowest incidence rates were found for recurrences due to drugs and exercise, although only 1 study 3 addressed both causes. The lowest prevalence rates were for drugs, with the differences also being significant for both prevalence and incidence (p < .01) (Figure 1, Table A3).Other potential explanations for the heterogeneity of the metaanalysis include the incorrect classification of anaphylaxis (underand over-diagnosis) in settings other than allergy departments,