Rates and Predictors of Remission From Chronic to Episodic Migraine
PHILADELPHIA—Among patients with chronic migraine, a majority either transition to high-frequency episodic migraine or continue to experience chronic migraine, while one fourth achieve remission within three years of follow-up, according to research presented at the 14th Congress of the International Headache Society.
Richard B. Lipton, MD, Professor and Vice Chair of Neurology at the Albert Einstein College of Medicine in Bronx, New York, and colleagues sought to estimate remission rates for patients with chronic migraine and assess potential remission predictors in persons progressing from chronic to episodic migraine. A total of 383 individuals were assessed for the American Migraine Prevalence and Prevention Study; chronic migraine subjects were identified in 2005 and underwent three consecutive years of follow-up.
The researchers assessed potential predictors of remission in two groups of participants. The persistent chronic migraine group included patients who met chronic migraine criteria in 2005, 2006, and 2007, and the remitted chronic migraine group included those who met chronic migraine criteria in 2005 but had either low-frequency migraine, no headache or probable migraine, episodic tension-type headache, or other episodic headache in 2006 and 2007.
Of those who reported chronic migraine in 2005, 52.7% (n = 238) had chronic migraine, and 64.6% (n = 292) had either chronic migraine or high-frequency episodic migraine, in at least one year of follow-up.
“Approximately 22% (n = 84) had chronic migraine in all three years, while 26% (n = 100) had chronic migraine in 2005 but had either low-frequency episodic migraine or no headache or probable migraine, or episodic tension-type headache, or other episodic headache in both 2006 and 2007,” Dr. Lipton’s group reported.
Predicting Remission Rates in Patients Who Have Chronic Migraine
Exploratory analysis suggested that depression, Migraine Disability Assessment (MIDAS) score, BMI, age of headache onset, allodynia, and medication use by class do not significantly predict remission of chronic migraine.
“Headache day frequency did predict remission with the more headache days per month that chronic migraine sufferers reported then the less likely they were to remit (odds ratio [OR], 0.08),” Dr. Lipton and colleagues noted. “Additionally, the current use of preventive therapy did predict remission; however, those chronic migraine sufferers utilizing a preventive therapy were half as likely to remit (OR, 0.45).”
The Disabling Effects of Chronic Migraine
The MIDAS questionnaire was used to assess the number of days missed from work or school because of disability and the number of days when effectiveness was reduced by 50% or more. Household work disability days during the preceding three months were also assessed. Rate ratios (RRs) for MIDAS scores, conditioned on age, were generated with negative binomial models.
Inclusion criteria were met by respondents (age 18 or older) with episodic migraine (n = 11, 249) or chronic migraine (n = 655). A total of 820 (7.3%) of those with episodic migraine reported occupational disability; 83 (12.7%) of those with chronic migraine reported occupational disability.
“Disability time varied strikingly as a function of age for both chronic migraine and episodic migraine,” noted Dr. Lipton’s group.
Subjects with chronic migraine showed approximately five times more work or school disability days than those with episodic migraine (RR, 5.06), as well as five times more household work disability days (RR, 5.53).
“Chronic migraine is remarkably disabling when compared to episodic migraine in terms of lost productive time or reduced effectiveness at work, school, and home,” Dr. Lipton and colleagues stated, adding that the trend continued throughout a patient’s lifespan. “In each domain, on an additive scale, age-related decline in lost time was greater for chronic migraine than episodic migraine.” Dr. Lipton’s team noted that the difference between chronic and episodic migraine may be even greater, because the model may underestimate impact due to the number of respondents who are occupationally disabled.
“These findings suggest that the burden of chronic migraine on productivity is substantially greater than that of episodic migraine throughout adult life,” reported the investigators.
MIDAS Scores in Patients With Remitted Versus Persistent Chronic Migraine
A total of 383 respondents with chronic migraine in 2005 and for whom data were collected from 2005 to 2007 were included in an analysis regarding disability impact following remission of chronic migraine (21.9% [n = 84] were classified as having persistent chronic migraine; 26.1% [n = 100] were classified as having remitted chronic migraine).
The investigators analyzed the difference between remitted and persistent chronic migraine on overall mean MIDAS score; the trend for MIDAS scores over time; and the interaction between these effects indicating the extent to which the MIDAS trend for remitted chronic migraine differed from that of persistent chronic migraine (the between group comparison, within group comparison, and interaction effect, respectively).
