Epidemiology of medication overuse headache in the general Swedish population.

AIMS The aim was to estimate the prevalence of medication overuse headache (MOH) in Sweden and to analyze the occurrence of this disorder in different population groups. METHODS A total of 44,300 randomly selected individuals (55% women), aged 15 years and above, were interviewed in a national telephone survey, using a standardized questionnaire including the International Headache Society criteria for MOH and questions about sociodemographic factors, headache history and medication use. RESULTS In Sweden, 3.2% (95% confidence interval (CI) 3.1-3.4), n = 1428) suffer from chronic daily headache (CDH) and out of those, 56% (n = 799) have MOH. The prevalence of MOH is 1.8% (95% CI 1.7-1.9). The mean age of onset was higher among men than women as well as among those with tension-type headache as primary headache compared to those who originally had migraine. A multivariate analysis showed that socioeconomic factors such as having a low level of education and/or a low household income were associated with MOH. CONCLUSIONS This is the first Swedish population-based study of MOH and we conclude that MOH is a significant public health problem in Sweden, as it is in other parts of the world.