Nancy A. Melville

October 04, 2011

October 4, 2011 (Las Vegas, Nevada) — Nearly 2% of women and 1% of men in midlife in the United States suffer from chronic migraine and, contrary to previous research, chronic migraine rates appear to be higher in blacks than whites, according to research presented here at the American Academy of Pain Management 22nd Annual Clinical Meeting.

Chronic migraine, defined as the presence of migraine with headache at least 15 days per month, has been reported in international populations at rates ranging from 0.9% to 5.1%. In an effort to determine prevalence in the American population, researchers evaluated the results of surveys sent to households in the United States in 2004.

Of the 162,756 surveys returned by respondents 12 years of age and older, 28,621 reported severe headache.

Of those, 19,189 (11.79%) met the International Classification of Headache Disorders criteria for migraine (17.27% females and 5.72% males), and 0.91% met the criteria for chronic migraine (1.29% females and 0.48% males). Rates varied according to age group, with the highest rates for females (1.9%) and males (0.8%) in the age range of 40 to 49 years.

The chronic migraine rate for females was 1.9% in the 19 to 29 year age group and 1.8% in the 30 to 39 year age group. Among blacks, the rates were 1.7% for females and 0.7% for males, although race did not factor independently after adjustment for sociodemographic factors.

Household income was inversely correlated with chronic migraine rates, with rates of 2.6% for females and 1.3% for males in households with annual incomes below $22,500. The rates in higher-income households were significantly lower — 0.5% for females and 0.2% for males in households with average annual incomes of $90,000 or more.

Chronic migraine has an effect on work, school, and social functioning. Severe headache (MIDAS grade IV) disability was reported by 37.97% of people with chronic migraine and by 9.51% of those with episodic migraine; the rate was higher among females than males.

"Chronic migraine is an extremely debilitating condition," said coauthor Dawn C. Buse, PhD, assistant professor in the Department of Neurology at the Albert Einstein College of Medicine of Yeshiva University in New York City.

"Women were hit harder than men, with rates of chronic migraine among females in their 20s, 30s, and 40s as high as 1.9%. This is the time of life when women experience the greatest demands in terms of education, career, and caring for families," she explained.

"This translates to more than 2 million women in the United States experiencing migraine more days than not, and some of them living with migraine every day, based on an estimated 155.6 million females in the United States, according to the 2009 US census."

"In addition, African Americans had higher rates of chronic migraine than Caucasians, which is the opposite of prevalence rates for migraine among these 2 groups."

The higher chronic migraine rates in lower-income households is a concern because of the lower levels of care the demographic likely receives.

"Those in households earning less than $22,500 per year had the highest rates of chronic migraine, adding pain and disability to financial stress," Dr. Buse said. "Sadly, these individuals may not have access to healthcare, may have never been diagnosed, and are the least likely to receive treatment and care that may help."

Clinicians, likewise, can face a host of challenges in treating chronic migraine, said John F. Rothrock, MD, professor, vice-chair, and medical director of the Department of Neurology at the University of Alabama School of Medicine in Birmingham.

Challenges include "the common presence of significant comorbidities, such as depression, anxiety, chronically disrupted sleep, and overuse of acute medications," he said.

Perhaps the most notable recent therapy to emerge in the treatment of chronic migraine is onabotulinumtoxinA (Botox, Allergan). Dr. Rothrock said he has had a fair amount of success with the treatment.

"Approximately a third of my chronic migraine patients whom I treat with [onabotulinumtoxinA] experience a 50% or greater reduction in their migraine burden," he said. "Many of them can discontinue treatment after 3 or 4 sets of injections without relapsing back into chronic migraine."

The study received funding through a research grant to the National Headache Foundation from Ortho-McNeil Neurologics. Additional analyses and poster preparation were supported by a grant from Allergan to the National Headache Foundation. Dr. Buse reports acting as a consultant and/or receiving research funding from Allergan, Endo Pharmaceuticals, Iroko Pharmaceuticals, MAP Pharmaceuticals, and Merck. Dr. Rothrock has disclosed no relevant financial relationships.

American Academy of Pain Management (AAPM) 22nd Annual Clinical Meeting: Poster Abstract 49. Presented September 22, 2011.


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