Chronic migraine (CM; ≥15 headache days per month, ≥3 months) is associated with a higher prevalence of comorbidities than episodic migraine (<15 headache days per month). However, it is unclear whether a similar pattern exists in Asian patients. To examine this, a retrospective matched cohort study was conducted using the Taiwan National Health Insurance Research Database. CM cases were defined as patients with at least one neurological outpatient visit with a primary or secondary ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) code of 346.11, diagnosed by neurologists at medical centers during 2007-2008. The study group was compared with patients suffering from other migraine subtypes and non-migraineurs in the general population. Both comparison groups were matched with CM sufferers at a 4:1 ratio by age, gender, urbanization level of the residence, income, and hospital setting. Relative risk (RR) was calculated using conditional logistic regression. Compared with patients with other migraines (n = 2,226), CM sufferers (n = 681) had a higher risk of hyperlipidemia (RR = 1.32; P = 0.041), asthma (RR = 1.77; P = 0.007), depression (RR = 1.88; P < 0.0001), bipolar disorder (RR = 1.81; P = 0.022) and anxiety disorders (RR = 1.48; P = <0.0001). Compared with the non-migraineurs (n = 3,790), CM sufferers (n = 948) had significantly increased risks of cardiovascular disease, sinusitis, asthma, gastrointestinal ulcers, vertigo and psychiatric disorders by 1.6-3.9-fold. In conclusion, CM is associated with significant comorbidities in Asian patients. Differences in the comorbidity profiles of CM compared with other migraines have highlighted that patients with CM differ not just in terms of headache frequency but also in other important aspects.
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