Shifting perspectives: diphenhydramine usage in anaphylaxis and urticaria across US emergency departments.

BACKGROUND

In recent years, the medical community's view on diphenhydramine for urticaria and anaphylaxis has shifted due to its side effects and the efficacy of second-generation antihistamines. The AAAAI's 2020 anaphylaxis guidelines discourage the use of first-generation antihistamines in the acute phase or to prevent biphasic reactions.

OBJECTIVE

Our study aimed to evaluate the usage of diphenhydramine in US emergency departments (EDs) for treating anaphylaxis and urticaria between 2019 and 2021, while also investigating the potential impact of the 2020 AAAAI guidelines on its utilization.

METHODS

A cross-sectional analysis was conducted using data from the Centers for Disease Control and Prevention's National Hospital Ambulatory Medical Care Survey (NHAMCS) spanning 2019-2021. NHAMCS collects nationwide data on patient visits to various healthcare facilities. This study focused on emergency department (ED) data, specifically examining patients with ICD-10 codes for anaphylaxis or urticaria who received at least one prescribed/given medication. Diphenhydramine administration was identified based on drug records. Design-based Pearson chi-square analysis with a significance threshold of P < .050 was employed.

RESULTS

Out of 450 cases with anaphylaxis and/or urticaria, 61.99 % (n = 276) involved diphenhydramine administration. Rates for anaphylaxis, urticaria, and both conditions were 57.99 % (n = 170), 69.45 % (n = 88), and 73.4 % (n = 18) respectively. No significant change in diphenhydramine use from 2019 to 2021 was found (P = .9421).

CONCLUSION

Our study indicates stagnant ED practices regarding diphenhydramine despite evolving guidelines. Bridging the gap between evidence and practice is crucial for patient care for urticaria and anaphylaxis. Future research should identify barriers hindering guideline adoption in US EDs.