Good and Bad Migraine Trends: Stable Prevalence But Rising Disability

A new systematic review shows that the prevalence of migraine has remained steady across the past three decades in the US, but the disability associated with it has grown.

More than one billion people around the world have migraine, but beyond the striking prevalence of this condition is the disability that accompanies it. For instance, a recent analysis of Global Burden of Disease data reported that, amongst 37 disorders affecting the nervous system, migraine was the third most burdensome globally (see MSC related news).

Over the last 30 years, many studies have characterized the prevalence and associated disability of migraine, but a new study goes a step further by looking at decades-long trends in these measures.

Researchers led by Fred Cohen, Icahn School of Medicine at Mount Sinai, New York City, US, and colleagues conducted a systematic review of US epidemiological survey studies to assess the changing patterns of migraine prevalence and disability between 1989 and 2018. They discovered that while the prevalence of migraine has remained stable, moderate to severe disability from migraine nearly doubled, from 2005 to 2018, according to the Migraine Disability Assessment Scale (MIDAS).

Robert Shapiro, Larner College of Medicine, University of Vermont, Burlington, US, said the findings are “an important contribution” to the field, but require further study to fully understand.

“These results show that we have been accurately assessing the prevalence of migraine over time. And I think it’s a testimony to the durability and reproducibility of the diagnostic questionnaires developed – they show we can identify people who have migraine irrespective of whether or not they’ve been diagnosed by a healthcare provider,” he said.

“But what this study also shows,” he continued, “is that it looks like the burden for people living with migraine is getting worse, with an overall increase in number of headache days and overall disability. So the big question we need to answer in future studies is: What might account for that?” according to Shapiro, who was not involved with the new research.

The study appeared in the May 2024 issue of Headache.

Reviewing the trends
Cohen, who works closely with study co-author Richard Lipton, Montefiore Headache Center and Albert Einstein College of Medicine, New York City, US, said he has always been interested in Lipton’s epidemiological work on migraine. After the completion of the OVERCOME study – a population-based, observational study of people living with migraine that aimed to understand the burden and stigma of the condition, and to identify potential barriers to treatment – Cohen said that he and Lipton brainstormed different ideas about other questions they might ask of the data.

“You only know something might be an issue if you first pose the question,” Cohen said. “The idea was that we could review the trends to see if there might be something that hadn’t previously been looked at.”

Cohen decided to examine how migraine prevalence and burden might have changed over time, scouring the scientific literature for US epidemiological studies representative of a general population.  In order to be included, those studies must have assessed whether participants met the diagnostic criteria for episodic or chronic migraine using the International Classification of Headache Disorders (ICHD), and also must have measured the burden of disease using MIDAS.

The researchers identified more than 1,600 records by searching on PubMed and other sources. They found that 26 articles from 11 studies, ranging from 1989 to 2018, met their study criteria. Among those 11 studies were well-known epidemiological investigations in the migraine field, such as the OVERCOME, CaMEO, and AMPP studies.

The team discovered that, overall, the prevalence of migraine remained steady over time across studies, ranging from 11.7% to 14.7%. Prevalence was higher in women, ranging from 17.1% to 19.2%, and 5.6% to 7.2% in men. Chronic migraine prevalence came in at 0.9% in adults (1.3% in women and 0.5% in men) and 0.8% in adolescents.

But, surprisingly, Cohen said, what changed dramatically was the burden of migraine. In 2005, the proportion of people who had migraine and moderate to severe MIDAS disability was 22%, but by 2018, that had jumped to 42.4%.

“We saw that the recorded burden kept going up over that time period,” he said. “When we looked at the scores from MIDAS, which is a very commonly used and well-validated scale for migraine studies, we found the scores for moderate to severe disability were trending upwards since 2005.”

Understanding why
Cohen said there could be numerous explanations for the difference in the trends for prevalence versus burden. One possibility is changes in study methodology. For instance, earlier epidemiological studies used mail-in surveys, which could have influenced who was willing to participate.

“These studies have now evolved into online questionnaires, and that may make participation easier for people who have more disability to complete,” he said. “Participation rates have also changed. So it may be what we are seeing is an artificial rise in burden – the change in the way we do our studies has captured this as opposed to people experiencing more burden.”

Shapiro said it’s possible that, with more education and awareness of migraine, people who have more symptoms may be more likely to participate in these kinds of studies than those who have fewer symptoms. But he expressed some skepticism.

“If that were the case, you might expect to see an overall rise in migraine prevalence because now you’d be including people with higher disability who were not previously assessed,” he said. “So I don’t know if it’s just participation bias. There are probably other factors involved.”

Cohen said there are other hypotheses that could explain the rise in burden. With the average frequency of headache also increasing, variables like changes in the climate or opioid use could be important.

“We know that weather is a common trigger for migraine. Maybe more severe weather effects trigger migraine more often,” he said. “And opioid use could also play a role, since it can often lead to medication overuse headache,” according to Cohen.

Cohen also pointed to other factors potentially at play. For instance, migraine stigma could lead to increased disability (see MSC related news), though trends in stigma levels over the years require further study. Changes in employment status could be important, too.

“I don’t have any definitive answers,” he said. “It’s going to be up to researchers to take the time to do the research and assess what’s going on with burden and how people are responding to these questionnaires.”

Shapiro agreed.

“These kinds of surveys are cross-sectional. They give us a snapshot of the population you sample. Unfortunately, comparing those snapshots doesn’t mean you can make a coherent motion picture out of it,” he said. “My guess is there are probably multiple factors that are responsible for this increase in burden and, as always, we need far more data to not only see what the different contributors are, but what the best remedies might be to manage them. That’s going to take time, and that’s going to take more research,” according to Shapiro.

Kayt Sukel is a freelance writer based outside Houston, Texas.

Image credit: 123RF Stock Photo.

Reference
Prevalence and burden of migraine in the United States: A systematic review.
Cohen et al.
Headache. 2024 May;64(5):516-32.