Conference Coverage

Commonalities challenge the threshold of high-frequency episodic and low-frequency chronic migraine



People with high-frequency episodic migraine and low-frequency chronic migraine may have similar treatment needs because characteristics of the two disorders overlap significantly, calling into question the existing threshold of 15 migraine headache days per month to distinguish low- and high-frequency migraine, according to an analysis of almost 17,000 patients from the Chronic Migraine Epidemiology and Outcomes (CaMEO) study presented at the virtual annual meeting of the American Headache Society.

Richard B. Lipton, MD, of Albert Einstein College of Medicine in Bronx, New York

Dr. Richard B. Lipton

“The results showed substantial overlap in levels of burden, anxiety, depression and health utilization, including outpatient, inpatient and emergency department visits, among CaMEO respondents with high-frequency episodic migraine and those with low-frequency chronic migraine,” said Richard B. Lipton, MD, of the Albert Einstein College of Medicine, New York.

The study analyzed data on 16,789 respondents to CaMEO, the longitudinal, web-based study designed to characterize the course of episodic and chronic migraine. The study population consisted of four subgroups based on the number of self-reporting monthly headache days (MHDs):

  • Low- and moderate-frequency episodic migraine (LFEM; zero to seven MHDs; n = 13,473).
  • High-frequency episodic migraine (HFEM; 8-14 MHDs; n = 1,840).
  • Low-frequency chronic migraine (LFCM; 15-23 MHDs; n = 1,035).
  • High-frequency chronic migraine (HFCM; 24 or more MHDs; n = 441).

Dr. Lipton pointed out that the International Classification of Headache Disorders, 3rd edition, defines chronic migraine as 15 or more MHDs for 3 months or more with criteria for migraine with or without aura met on 8 days a month or more. It defines episodic migraine as less than 15 MHDs.

The study characterized migraine subgroups by various demographics. “The more frequent headache categories were associated with slightly older age of onset with a higher proportion of BMI [body mass index] in the obese range and overall with lower levels of household income and education,” Dr. Lipton said.

Similar headache characteristics

A comparison of headache characteristics and headache-related disabilities across subgroups revealed a number of commonalities between the HFEM and LFCM subgroups, Dr. Lipton said. Among them were presence of mild to severe allodynia, disability grade, interictal burden, and anxiety and depression scores. For example, 47.3% of the HFEM subgroup and 54.9% of the LFCM subgroup had Patient Health Questionnaire–9 depression test scores greater than 10.

The study also evaluated patterns of consultation, diagnosis, and health resource utilization and found similar rates between the HFEM and LCFM subgroups, Dr. Lipton said. Rates of overnight hospital stay in the past 6 months were almost identical between the two subgroups: 4.1% for the former and 4.2% for the latter. One striking difference between the two subgroups: the rate of medication overuse per ICHD-3 recommendations was 40.5% in HFEM and 63% in LFCM.

“These finding suggest that the treatment needs of people with HFEM may be similar to those of people with LFCM, suggesting that the 15-MHD threshold currently recommended by the ICHD-3 may merit reconsideration,” Dr. Lipton said.

An arbitrary cutoff?

The findings raise a valid point about reevaluating the thresholds for low- and high-frequency migraine, said Andrew Charles, MD, director of the Goldberg Migraine Program at the University of California, Los Angeles. “My own personal view is that they’re the same thing,” he said of HFEM and LFCM; The 15-day cutoff, he said, is “somewhat arbitrary.”

Dr. Charles suggested migraine categories address frequency and not characteristics – episodic versus chronic – and use a range rather than a threshold. “Define a range that’s more like 10-20 days per month rather than having that point at 15,” Dr. Charles said. “People sometimes make the mistake of thinking that that classification reflects some underlying pathophysiology, and that may not be necessarily true.”

Dr. Lipton disclosed financial relationships with Alder Biopharmaceuticals, Allergan (now AbbVie), Amgen, Biohaven Pharmaceuticals, Dr. Reddy’s/Promius, Electrocore, Eli Lilly, eNeura Therapeutics, GlaxoSmithKline, Lundbeck (Alder), Merck, Pernix Therapeutics, Pfizer, Supernus, Teva, Trigemina, Axsome Therapeutics, Vector, and Vedanta. Dr. Charles disclosed he is a consultant to Amgen, Biohaven Pharmaceuticals, Eli Lilly, Lundbeck, and Novartis.

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