C-reactive protein in migraine sufferers similar to that of non-migraineurs: the Reykjavik Study.

C-reactive protein (CRP), a marker of inflammation, has been associated with cardiovascular disease. Risk of cardiovascular disease is increased in migraineurs with aura. Results from a clinical report, case-control and a cohort study suggest that CRP is elevated in migraineurs compared with non-migraineurs. We examined the proposed association in a case-control study nested within two large population-based studies. The relationship between migraine and CRP (high-sensitivity CRP) was studied in 5906 men and women aged 55.0 +/- 8.5 years in the Reykjavik Study and 1345 men and women aged 27.7 +/- 5.5 years from the Reykjavik Study for the Young. A modified version of the International Headache Society's criteria was used to categorize people into migraineurs (two or more symptoms) or non-migraineurs. Migraineurs with visual or sensory symptoms were further defined as having migraine with aura (MA) or without aura (MO). Multivariable-adjusted CRP levels were similar in migraineurs and non-migraineurs for men (0.83 vs. 0.79 mg/l, P = 0.44) and for women (0.87 vs. 0.87 mg/l, P = 0.90). When further stratified by migraine aura and age, no differences were found between non-migraineurs, MO and MA among men. In women, CRP levels were borderline higher in those with MO compared with non-migraineurs and those with MA (1.01 mg/l vs. 0.81 and 0.75 mg/l, P = 0.08 and P = 0.08) in age group 19-34 years, but significantly lower in age group 60-81 years (0.52 mg/l vs. 1.07 and 1.01 mg/l, P = 0.007 and P = 0.03). CRP levels were not increased among migraine sufferers compared with non-migraineurs. Older women migraineurs without aura had lower CRP values than non-migraineurs and migraineurs with aura.