Rationale: We have previously reported increased anaphylaxis hospitalizations but stable fatal anaphylaxis rates over a 21-year period in England and Wales. To explore whether this is related to a true increase in disease, we evaluated time trends in intensive care unit (ICU) anaphylaxis admissions.
Methods: We assessed trends in hospital admission to intensive care units requiring mechanical ventilation between 2008 and 2012 using nationally-held datasets. Incident rate ratios (IRR) were calculated for Level 3 admissions with the following ICD-10 diagnostic codes: T780 food anaphylaxis, T782 unspecified cause, T886 iatrogenic, X23 insect sting.
Results: There were 833 admissions due to anaphylaxis over a 5-year period: 160 due to food, 8 insect stings, 273 medication/iatrogenic and 392 cause unspecified. ICU admissions increased significantly over the study period for all anaphylaxis, with an IRR of 1.14 (95% CI 1.08-1.20, P<0.001); for iatrogenic anaphylaxis 1.20 (95% CI 1.10-1.31, P<0.001); food anaphylaxis 1.16 (95% CI 1.04-1.29, P=0.01); anaphylaxis of unspecified cause 1.10 (95% CI 1.03-1.19, P=0.005). We found no evidence for an increase in anaphylaxis due to insect venom IRR 0.66 (95% CI 0.36-1.10 p=0.14). The age distribution of anaphylaxis admissions by cause was similar to that previously described for fatal anaphylaxis.
Conclusions: Rates of critical care admissions for anaphylaxis have increased, in contrast to fatal anaphylaxis rates. This suggests that recent trends for food and drug-induced anaphylaxis may be explained by a true increase in anaphylaxis with a concomitant improvement in emergency care.