Imported fire ant immunotherapy prescribing patterns in a large health care system during an 11-year period.

Background: The first large-scale evaluation of prescribing patterns for imported fire ant (IFA) in a large US health care system was published by Haymore et al in 2009. In this first evaluation of prescriptions from 1990 to 2007, the most often prescribed maintenance IFA prescription was 0.5 mL of 1:200 wt/vol.

Objective: To provide an updated description of IFA prescribing patterns over the ensuing 11 years from same large health care system.

Methods: We reviewed 1349 new IFA prescriptions written from 2007 to 2018, from a large nationwide health care system, with primary end points being maintenance prescription strength and prescribing patterns.

Results: In comparison to the data published by Haymore et al in 2009, which reported that 17% of the prescriptions were written for 0.5 mL of 1:100 wt/vol maintenance, we found that 69% (95% CI: 66.4%-71.4%) of IFA prescriptions written in the past 11 years were for the maintenance concentration of 0.5 mL of 1:100 wt/vol. We further studied the linear trend over time of percentage of prescriptions written for individual concentrations and observed that the percentage of 1:100 wt/vol prescriptions increased 3.5% yearly (R = 0.68, P < .001) from 2007 (40.0%, 95% CI: 24.6%-57.7%) to 2018 (84.4%, 95% CI: 77.4%-89.5%).

Conclusion: Our study shows significant improvement in the accuracy and precision of IFA immunotherapy dosing for patients with IFA hypersensitivity, with ascendancy of 0.5 mL 1:100 wt/vol as the predominant treatment dose. A total of 87% of patients within our study were treated within the parameter recommendations, a stark improvement from findings in the 2009 Haymore study.