Regional differences in EpiPen prescriptions in the United States: the potential role of vitamin D

Background The epidemiology of anaphylaxis is uncertain, especially its geographic distribution. Objective To address this deficit, we examined regional rates of EpiPen prescriptions in the United States. Methods EpiPen prescriptions in 2004 were obtained for all 50 states and Washington, DC, from NDCHealth, Pharmaceutical Audit Suite (Alpharetta, Ga). Data included the number of total filled prescriptions, including refills, and the actual number of EpiPens prescribed. Several data sets were used to obtain state-specific populations, as well as multiple demographic, health, and weather characteristics. State population was used to calculate the average number of prescriptions written per person. Results Overall, there were 1,511,534 EpiPen prescriptions filled during 2004. These prescriptions accounted for 2,495,188 EpiPens. On average, there were 5.71 EpiPens prescribed per 1000 persons. Massachusetts had the highest number of prescriptions per 1000 persons (11.8), whereas Hawaii had the lowest (2.7). In addition to state-to-state variation, there was an obvious regional difference: New England (Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, Maine) had the highest values, with 8 to 12 EpiPen prescriptions per 1000 persons, whereas the southern states (between and including California and Mississippi) had only 3 prescriptions per 1000 persons. The New England finding persisted even when controlling for all available factors (eg, population demographic characteristics, number of health care providers, prescriptions for other medications). Conclusion A strong north-south gradient was observed for the prescription of EpiPens in the United States, with the highest rates found in New England. Clinical implications The regional differences in EpiPen prescribing may provide important etiologic clues (vitamin D status) and merit further investigation.