Striking north-south differences in EpiPen prescribing

A new study suggests strong variation in the occurrence of anaphylaxis between the northern and southern U.S. Anaphylaxis is a severe allergic reaction that can be fatal without treatment with epinephrine.

The striking north-south differences in EpiPen prescribing, a marker of anaphylaxis risk, currently are without explanation. The investigators hypothesize, however, that low levels of vitamin D from lack of sunshine, may play a role and that this hypothesis requires further investigation.

The study, “Regional differences in EpiPen prescriptions in the United States: The potential role of vitamin D,” can be found in the July 2007 issue of the Journal of Allergy and Clinical Immunology (JACI), the peer-reviewed journal of the American Academy of Allergy, Asthma and Immunology (AAAAI).

Carlos A. Camargo, MD, DrPH, FAAAAI, and colleagues obtained data on EpiPen prescriptions in 2004 for all 50 states and Washington, D.C. They used state populations to calculate the average number of prescriptions written per person.

Researchers found that on average, there were 5.71 EpiPens prescribed per 1000 persons in the U.S. The highest number of prescriptions per 1000 persons was in Massachusetts with 11.8. Hawaii had the lowest with 2.7 prescriptions per 1000 persons.

The team also found a regional difference in the number of prescriptions. New England had the highest values with 8 to 12 EpiPen prescriptions per 1000 persons, and southern states had only 3 prescriptions per 1000 persons. These findings persisted even after adjusting for differences in population characteristics, healthcare data and other factors.

The explanation for the strong variation between northern states and southern states is not clear. The investigators note, however, that southern states have a warmer climate and more year-round sunlight and that their findings support recent speculation about a link between low Vitamin D levels from less sunlight, and higher incidence of respiratory and allergic diseases. This study suggests that perhaps more year-round sunshine in the south led to higher Vitamin D levels and could explain the north-south difference in the incidence of respiratory and allergic disease.

The AAAAI represents allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic disease. Allergy/immunology specialists are pediatric or internal medicine physicians who have elected an additional two years of training to become specialized in the treatment of asthma, allergy and immunologic disease. Established in 1943, the AAAAI has more than 6,500 members in the United States, Canada and 60 other countries. The AAAAI serves as an advocate to the public by providing educational information through its Web site at