Investigating health care pathways for anaphylaxis: Seeing the bigger picture through linked data.

Background: Anaphylaxis is increasing in Australia involving all levels of the health care system. Although guidelines recommend calling an ambulance and 4-hour observation, knowledge gaps exist regarding where people experiencing anaphylaxis receive care. Objective: We sought to examine care pathways for anaphylaxis in Western Australia and factors associated with seeking care from ambulance versus the emergency department (ED), and subsequent hospital admission. Methods: A cross-sectional study was undertaken using linked ambulance, ED, hospital, and mortality data. The proportion of anaphylaxis events following each care pathway from 2010 to 2017 was examined. Multivariable logistic regression was used to determine factors associated with ambulance versus ED as the first point of care, with additional models to determine risk of admission. Results: Most of the 16,456 anaphylaxis events followed 6 distinct care pathways. ED was first point of care in 9,713 (59.0%) events; ambulance in 5,926 (36.0%); and hospital in 817 (5.0%). Factors associated with ambulance attendance compared with ED were metropolitan region (odds ratio [OR], 3.00; 95% CI, 2.70-3.34), age more than 65 years (OR, 2.98; 95% CI, 2.54-3.50), and anaphylaxis occurring during the day (OR, 1.31; 95% CI, 1.21-1.42). Risk of subsequent hospitalization was associated with food trigger in ED (OR, 1.52; 95% CI, 1.11-2.07), age more than 65 years (OR, 1.48; 95% CI, 1.24-1.77), children younger than 5 years (OR, 1.24; 95% CI, 1.08-1.41), and history of cancer (OR, 1.36; 95% CI, 1.18-1.56). Conclusions: Most people experiencing anaphylaxis present directly to ED; however, ambulance care is still substantial and around half the events involved observation in the hospital. Discrepancies in recording of anaphylaxis across linked data sets highlight gaps in current burden data, supporting the need for improved reporting.