Chronic migraine should be distinguished by 8 headache days per month based on migraine burden, according to new research presented at the American Headache Societies’ Virtual Annual Scientific Meeting.

“This study focuses on the diagnostic criteria of chronic migraine differentiated from migraine,” said Ryotaro Ishii, MD, PhD, 2021 recipient of the AHS Harold G. Wolff Lecture Award, visiting scientist, Mayo Clinic, Phoenix, Arizona.

Researchers used data from the American Registry of Migraine Research to analyze a population of 836 patients with migraine aged 18 or older between February 1, 2016, and March 6, 2020. Participants were divided into 4 subgroups; Group 1 defined as 0 to 7 headache days per month; Group 2 defined as 8 to 14 headache days per month; Group 3 defined as 15 to 23 headache days per month; and Group 4 defined as 24 or more headache days per month.

Age, gender, race, educational level, household income, employment status, marital status, and an evaluation of demographics were taken into account when assessing the data.

Patients with 8-14 headache days per month had comparable levels of disease burden in measures including headache intensity, work productivity, pain interference, anxiety, and depression to those with 15-23 migraine days per month.

Patients in the 0-7 headache days per month group had significantly lower scores compared to the other groups, and patients with 24 or more headache days per month had significantly higher scores compared to the other groups.

These findings suggest that previously reported differences between chronic migraine and episodic migraine have been influenced by patients with 0-7 headache days per month, and patients with 24 or more headache days per month.

“These results suggest that patients with 8-14 and 15-23 headache days per month have very similar disease burden,” Dr Ishii stated.

“Our conclusion of this study is that the current threshold of 15 headache days does not adequately reflect substantial differences in disability across the full spectrum of headache frequency,” continued Dr Ishii.

In an email interview with Neurology Learning Network, Dr. Rotaro Ishii expanded on the significance of these findings and the impact on quality of life for patients experiencing 8-14 headache days per month.

Q&A:

What drove you to conduct this evaluation?

Dr Ishii: Based on my clinical experience, many patients with migraine with more than two headaches per week worry about whether they will have a headache or not every day. I thought they were not so much different from those who had 15 to 24 headache days per month. And I decided to make sure of my hypothesis.

What were the most important findings, in your opinion?

Dr Ishii: The patients with Episodic Migraine (EM) who have a high frequency of headache - 8-14 headache days per month - appear highly similar to those with CM who have 15-23 headache days per month.

What would you like to see next with this type of data? Would you like to see research in days vs severity in terms of defining chronic migraine?

Dr Ishii: The results of this study should be confirmed by another study with using the other data set. I think it is also important to focus on patients with 24 or more headache days per month. I am interested in the other cut-off of headache days, such as between 30 days and 29 days, and their significance.

 —Erin McGuinness

Ishii, R. The 15-day Threshold Does Not Adequately Reflect Substantial Differences in Disability Across the Full Spectrum of Headache Frequency. Presented at the American Headache Society Virtual Annual Scientific Meeting 2021; June 4-6.