Incidence and patient demographics of pre-hospital anaphylaxis in Tasmania, Australia

Abstract

Introduction It is widely accepted that anaphylaxis is an increasing problem worldwide. This inquiry into pre-hospital incidence and patient demographics is useful to determine the status of anaphylaxis in Tasmania, Australia. The objective of this study was to determine the incidence of pre-hospital anaphylaxis in Tasmania and identify trends in characteristics of affected patients. Methods Raw data was searched and extracted from Ambulance Tasmania electronic recording system and case records for the period 1 January 2008 to 31 December 2011 following approval from the University of Tasmania’s Higher Education Research Council. This involved a chart review of 226,421 cases with the search parameters of anaphylaxis and allergy/allergic reaction. Results There were 1014 patients classified as having an allergic reaction (including the most severe form of anaphylaxis). Of the atopic group, 370 (26.7%) were given a final primary diagnosis of anaphylaxis. The distribution of anaphylaxis cases was higher in adult females: 180 (61.6%) versus 112 (38.4%) in males. Interestingly 21.1% of the total anaphylaxis cases were paediatric (n=78) with a greater percentage of male (57.7%) to female (42.3%) cases in the paediatric population. Aetiology was identified in 83.5% of the cases: envenomation (insects) 131 (42.4%); food 113 (36.6%); medication 52 (16.8%); known other 10 (3.2%); exercise 3 (<1%). Sixty-one patients (16.5%) had anaphylaxis from an unknown aetiology. Almost two-thirds (61.9%) of the cases were from southern Tasmania. Conclusion These findings suggest that almost a quarter of all calls for allergy or allergic reaction are of a severe potentially life-threatening nature, with the most common aetiology being envenomation from insects (jack jumper bites).