Epidemiological shifts and temporal trends in emergency department anaphylaxis management: An 18-year longitudinal study in northern Thailand.

BACKGROUND: Although anaphylaxis incidence is rising globally, long-term longitudinal data from Southeast Asia remain scarce. This study evaluates 18-year trends in anaphylaxis visit rates, etiological triggers, and clinical management in Northern Thailand, specifically assessing the impact of institutional protocols implemented in alignment with the 2017 Thai National Clinical Practice Guidelines for Anaphylaxis. METHODS: We conducted an 8-year retrospective study (2017-2024) at a tertiary university hospital, integrating data with a previous 10-year cohort (2007-2016) under an identical clinical adjudication and exclusion protocol. Cases were identified via ICD-10 codes and manually adjudicated using 2006 NIAID-FAAN clinical criteria. We analyzed demographics, triggers, management metrics, and outcomes using multivariable logistic regression. Longitudinal trends adjusted for annual Emergency Department (ED) volumes were evaluated using a Poisson log-linear regression model with a log offset. RESULTS: Among 647 anaphylaxis events (626 patients), the 2017-2024 presentation rate was 360.7/100,000 ED visits in children and 282.4/100,000 in adults. Adjusting for ED volume, Poisson regression revealed a compounding yearly rate increase of 10% in adults (IRR = 1.10, 95% CI: 1.09-1.12, p < 0.001 ), while pediatric rates remained volatile without a longitudinal trend (IRR = 1.01, 95% CI: 0.98-1.05, p = 0.40 ). Total institutional encounters rose significantly (IRR = 1.09, 95% CI: 1.08-1.10, p < 0.001 ). Comparing to the previous 2007-2016 data, food led triggers (49.6%), with growing proportions of shellfish (34.2%) and edible insects (10.5%, p < 0.001 ). Medications caused 20.2% of cases, whereas Hymenoptera stings (10.2%) decreased significantly ( p < 0.001 ). Primary manifestations were cutaneous (95.4%), respiratory (66.8%), and gastrointestinal (53.3%). Over the protocol integration timeline, ED intramuscular epinephrine administration rose from 87.5% to 98.3% ( p < 0.001 ), and mean door-to-treatment time dropped from 16.3 to 10.3 min ( p = 0.03 ). Fatality was zero; however, the discharge prescription rates for self-injectable epinephrine remained stagnant at 7.6%. CONCLUSIONS: Anaphylaxis ED visit rates demonstrated a significant longitudinal increase over 18 years, driven by the adult population and characterized by an evolving distribution of food triggers toward shellfish and edible insects.