Chronic migraine and chronic daily headache in the Asia-Pacific region: A systematic review

Background: Data on the prevalence and characteristics of chronic migraine (CM) and chronic daily headache (CDH) in the Asia-Pacific region are limited. Methods: We performed a systematic review on this topic, searching for studies published from 1996 to 2012 that reported the prevalence (population-based studies) or frequency (clinic studies) of CM or CDH. We calculated 95% confidence intervals for the prevalence in population studies. Results were qualitatively described. Results: Seven population studies and 19 hospital clinic studies from Asia were included. The CDH prevalence in population studies was 1.0-3.9% (median 2.9%). Only two studies from Taiwan reported the population prevalence of CM (1.0% and 1.7%). In addition, we derived a prevalence of 0.6% from a Malaysian study. Eleven clinic studies reported a CM frequency of 4.7-82% (median 52%) as a subset of CDH; classification of medication overuse varied. CM was associated with substantial disability. Conclusions: The prevalence of CM and CDH in Asia appears lower than the global average, but applying the above prevalence estimates to the Asia-Pacific population would suggest that CM alone affects between 23 and 65 million individuals in the region.