Researchers in London used national hospital discharge statistics from 1990-1 to 2000-1 to identify trends in admissions for four allergic conditions (anaphylaxis, angio-oedema, food allergy, and urticaria).
Over 49,000 admissions occurred during the 11-year study period. Total admissions increased from 1,960 in 1990-1 to 6,752 in 2000-1. This almost certainly reflects an increase in incidence, say the authors.
The largest increases in rates were for anaphylaxis and food allergy. Anaphylaxis rates rose from 6 to 41 per million, and food allergy rates rose from 5 to 28 per million over this period. Admissions for urticaria and angio-oedema have risen more modestly, from 20 to 43 per million and 10 to 17 per million respectively.
They suggest that these changes could be caused by increasing exposure to environmental risk factors (such as peanuts and other foods or latex), to an increased susceptibility in the population to these allergens, or to a combination of these factors.