Based on Global Burden of Disease data (http://ghdx.healthdata.org/gbd-results-tool, accessed February 2022)
However, there is a much greater uncertainty about this estimate of disability for migraine than for anxiety or depression. This can be seen from the width of the black lines on the graph above. Researchers provide these ranges to indicate how sure they are about their results. In the case of migraine, the level of disability could be as high as 53,000 YLD or as low as 4,600 YLD. We need better research to get more certainty about these results.
The high level of disability is consistent with what we know about migraine disease. The most severe and debilitating form of migraine is chronic migraine, when headache occurs on 15 days or more each month. We don't know exactly how many people have chronic migraine in NZ, as this has never been measured. From international research, it is estimated that 7-12% of people with migraine have chronic migraine. This would correlate to 45,000-77,000 people in NZ. Other studies estimate that 1-2% of the whole population have chronic migraine, which would mean that between 52,000-104,000 people in NZ are affected (based on 2023 Census estimates).
People with migraine who have 14 or fewer headache days a month are said to have "episodic" migraine, This can also be classed into different types, from low frequency (0-3 headache days a month), moderate frequency (4-7 headache days a month) and high frequency (8-14 headache days a month). High frequency episodic migraine can cause a similar level of disability to chronic migraine. From a large US population study of people with migraine (including over 21,000 subjects), 58% of people with migraine had low frequency episodic migraine, 19% had moderate frequency episodic migraine, and 11% had high frequency episodic migraine.