Prevalence of chronic headache with and without medication overuse: associations with socioeconomic position and physical and mental health status.
Near-daily intake of acute symptomatic medication for frequent headache increases the risk for medication-overuse headache (MOH). Chronic headache (CH) and MOH prevalences are inversely related to socioeconomic position (SEP). It is not known how SEP influences the health status of people with these headaches. This cross-sectional study examined the prevalence of CH in Denmark; possible associations between CH and education, work status, and income; and the health status of people with CH across socioeconomic strata. A total of 129,150 individuals aged ⩾ 16 years were invited to the 2010 Danish National Health Survey. Data on SEP indicators and purchases of prescription drugs in 2009 were retrieved from national registers. Respondents with headache ⩾ 15 days per month over 3 months were classified as having CH. Those with concurrent over-the-counter analgesic intake of ⩾ 15 days per month or prescription medication overuse (⩾ 20 or ⩾ 30 defined daily doses per month depending on the drug or drugs) were classified as having MOH. Associations between headache and SEP were analyzed by logistic regression, and associations between headache and health status scores, by linear regression. Physical and mental health composite scores (SF-12) were summarized per headache group, stratified by SEP, and compared to the sample mean. Analyses were adjusted for stratified sampling and nonresponse. The response rate was 53.1%. CH prevalence was 3.3% with 53.0% of cases having concurrent medication overuse (MOH prevalence 1.8%). CH was more prevalent among those individuals with low SEP. Health status scores were significantly lower among persons with CH in all SEP categories. The burden of CH can be reduced by preventing and treating MOH.