A recent report published in the April 2013* issue of the Journal of the American Academy of Dermatology looks at how many people in the U.S. contract forms of the skin disease alopecia areata (AA). The report is a repeat of a study published in 1995**. Both studies used the population of Olmstead County, Minnesota and both arrive at a figure close to 2 percent. However, while you might have heard or read that 2 percent of the U.S. population, or nearly 6 million Americans, currently have AA, that’s not quite correct. The 2 percent figure refers to estimated lifetime risk — in other words, how many people are at risk at some time during their entire lives of having any form of AA, whether it be a single hairless patch at one extreme or complete hair loss (universalis) at the other. It does notmean that 2 percent of people in the U.S. today are currently living with the condition.
When the original study of Olmstead County residents for the span 1975 to 1989 was repeated for the years 1990 to 2009, some interesting findings are revealed:
The lifetime risk rose from 1.7 percent to 2.1 percent.
In the later study, the incidence over time increased, from 15.3 cases per 100,000 people per year from 1990-94, to 24 cases per 100,000 people from 2005 to 2009. (In the earlier study, the incidence over time did not change at all.)
While we’re happy that this follow-up study was conducted, it’s not clear exactly what the data mean. The incidence of AA could be increasing, or it could be exactly the same, with the difference simply due to the fact that more people are being diagnosed. Additional research is needed to determine what additional significance, these findings might have.
*Incidence of alopecia areata in Olmsted County, Minnesota 1990-2009 Journal of the American Academy of Dermatology Volume 68, Issue 4, Supplement 1 , Page AB106, April 2013
** Incidence of alopecia areata in Olmsted County, Minnesota, 1975 through 1989. Mayo Clin Proc. 1995 Jul;70(7):628-33.
