STOWE, VT—Epidemiologic studies have demonstrated that migraine has a clinically variable course, reported Richard B. Lipton, MD, Professor of Neurology, Psychiatry and Behavioral Sciences, and Epidemiology and Population Health at Albert Einstein College of Medicine (AECOM), Bronx, New York. Some patients have headaches that remit, and they become symptom-free; others have migraines that persist in a relatively stable fashion for many years. A smaller subset of migraineurs experience progression, which can be clinical, functional, or anatomic in nature.
At the 18th Annual Headache Symposium, Dr. Lipton, who is also Director of the Montefiore Headache Unit at AECOM, discussed data from two key migraine studies, the Frequent Headache Epidemiology (FrHE) study and the American Migraine Prevalence and Prevention (AMPP) study, which examined risk factors for migraine and migraine progression.
Evolution of the Understanding of Migraine
Until 1990, migraine was viewed primarily as an episodic pain disorder, in which blood vessels played an important role in the development of pain, explained Dr. Lipton. Treatments for migraine included analgesics for pain and ergots for blood vessel disease. During the “triptan era”—from 1990 to 2002—migraine was understood as a disorder that could be chronic or episodic, he said. The treatment goal during this period was relief of pain, and with the introduction of the concept of chronic headaches, researchers began to consider a role for preventive therapy. Since 2002, migraine has been conceptualized as a disorder that is chronic and sometimes progressive. The goal of treatment continues to be relief of pain, but triptans and other acute treatments are prescribed early to modify the natural history of migraine. Increasingly, treatment is focused on preventing migraine progression to chronic daily headache.
Risk Factors for Migraine and Migraine Progression
In the FrHE study, researchers looked at progression of migraine disease in a population-based epidemiologic study that contained cross-sectional, case-control, and cohort components. The control group comprised patients who had low-frequency, episodic headaches.
People with chronic daily headache were more likely to be female, younger, heavier, and depressed, with lower education levels and medication overuse. Snoring and head injury were also associated with chronic daily headache. With respect to treatment, aspirin (but not acetaminophen) appeared to be protective. Excessive use of OTC pain relievers that contain caffeine, as well as combinations containing narcotics and barbiturates, was associated with increased risk for chronic daily headache. Dietary consumption of caffeine was also a risk factor for chronic daily headache. Stressful life events (eg, moving or relocating, changes with children, death in the family, and work-related changes) were reported more often in the period prior to developing chronic daily headache.
BMI was a strong predictor of migraine progression; a BMI of 30 or greater was associated with a fivefold increased risk for chronic daily headache. Also, baseline headache frequency was a predictor of progression; as frequency increases to more than one headache per week, so does the probability of transitioning to chronic daily headache.
Among approximately 800 people with episodic headache, 3% had developed new-onset chronic daily headache, 6% developed headaches of intermediate frequency, and 91% continued to experience a relatively stable headache frequency at one-year follow-up.
NSAID Use High, Opiates and Barbiturates May Be Harmful
In the AMPP study, surveys were mailed in 2004 to 120,000 US households (~ 300,000 individuals). Of the 185,000 people who returned surveys, approximately 28,000 (12 or older) had severe headache. In 2005, a random subsample was surveyed about migraine risk factors, and about 18,000 responded. A large number of responders self-reported chronic daily headache, and a smaller group reported probable migraine.
Participants reporting chronic daily headache were older and heavier, less likely to be employed full time, 2.5 times as likely to have other chronic pain disorders, twice as likely to be disabled and to have major depression, and almost twice as likely to self-report anxiety disorders. Many of the comorbidities that are regularly associated with migraine are even more strongly associated with chronic migraine, Dr. Lipton observed.
Regarding use of medical resources, patients with chronic migraine are more than twice as likely to go to the emergency department for headaches, 50% more likely to go to the emergency department for other medical problems, three times more likely to see their primary care physician for headache, and 70% more likely to see their primary care physician for other medical reasons.
Among 8,200 participants who reported having migraine in 2005 and who completed a follow-up survey in 2006, 82% continued to have episodic migraine, 2.5% transitioned to chronic daily headache, and 14% reported other outcomes (eg, remission, failure to meet migraine criteria).