Body mass index and episodic headaches: a population-based study.

BACKGROUND We investigated the influence of the body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]) on the frequency, severity, and patterns of treatment of migraine, probable migraine (PM), and severe episodic tension-type headache (S-ETTH). METHODS A validated questionnaire was mailed to 120 000 households selected to be representative of the US population. The participants were divided into 5 categories based on BMI: underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), obese (30.0-34.9), and morbidly obese (>35.0). Analyses were adjusted by covariates that included demographic variables (age, sex, race, and income), duration of illness, comorbidities, use of preventive medication, and use of opioids. RESULTS The response rate was 65%. We identified 18 968 individuals with migraine, 7564 with PM, and 2051 with S-ETTH. The distribution of very frequent headaches (10-14 d/mo) was assessed by BMI. Among individuals with migraine, very frequent headaches (10-14 d/mo) occurred in 7.4% of the overweight (P = .10), 8.2% of the obese (P < .001), and 10.4% of the morbidly obese (P < .0001) subjects, compared with 6.5% of those with normal weight, in adjusted analyses. Among individuals with PM and S-ETTH, the differences were not significant (P = .20). The disability of migraineurs, but not of those with PM or S-ETTH, also varied as a function of BMI. Among migraineurs, 32.0% of those with normal weight had some disability compared with 37.2% of the overweight (P < .01), 38.4% of the obese (P < .001), and 40.9% of the morbidly obese (P < .001) subjects. CONCLUSION These findings support the concept that obesity is an exacerbating factor for migraine but not for other types of episodic headaches.