LOS ANGELES – The lifetime prevalence of self-reported migraine in the general population rose considerably in a recent 8-year period, suggested a study of roughly 37,000 middle-aged adults in Denmark.
From 1994 to 2002, the proportion reporting that they had ever had migraine rose by 32%, from a prevalence of 18.5% to 24.5% (P less than .001), Dr. Han Le of the University of Copenhagen reported at the annual meeting of the American Headache Society.
Dr. Han Le
By type, there was a 68% increase in the prevalence of migraine with aura (from 5.6% to 9.4%; P less than .001) and a 16% increase in the prevalence of migraine without aura (from 13% to 15.1%; P less than .001), although the latter remained considerably more common (BMJ 2012 July 2 [doi:10.1136/bmjopen-2012-000962]).
"So are we having a micro-epidemic? ... We do believe that there is an increase, but [it] may not be as high as we are finding," Dr. Le commented, noting that that short time span over which the change took place would favor environmental explanations over genetic ones.
"Some part may be explained by more awareness or increased medical consultation. We do know for a fact that medical consultation has increased in Denmark. But there aren’t any campaigns to make people more aware of migraine," she elaborated. "A small part of the subjects participated in both surveys, so perhaps when they saw the migraine questions for the first time, they kind of thought more about it and went to a physician. That’s hard to tell."
In additional study findings, low education and high physical workload and activity increased the risk only of migraine without aura, whereas low body mass index increased the risk only of migraine with aura. Thus "different environmental factors seem to increase the development of migraine with aura and migraine without aura," she commented.
The investigators analyzed data from the Danish Twin Study, in which 20- to 41-year-olds in the general population were asked if they had ever experienced migraine and, if so, if they had had antecedent visual disturbances. Analyses were based on data from 22,053 adults in 1994 and from 14,810 adults in 2002.
Age-stratified analyses showed that most of the increase occurred among individuals aged older than 32 years. There was a significant increase among men and women individually, with the relative increase comparable for the sexes.
The investigators conducted an additional analysis of migraine risk factors among 13,498 adults aged 18-41 years who were free of migraine in 1994 and completed surveys in both study years.
Results showed that these adults were more likely to develop migraine if they had low back pain (odds ratio, 1.3), low education (OR, 1.3), hard physical workload (OR, 1.1), hard physical activity (OR, 1.2), and a body mass index of less than 18.5 kg/m2 (OR, 1.3).
In stratified analyses, only one of these factors (low back pain) was a risk factor for both types of migraine, according to Dr. Le. Low education as well as high physical workload and activity were risk factors only for migraine without aura, whereas low BMI was a risk factor only for migraine with aura.
Dr. Le disclosed no relevant conflicts of interest.