The impact of migraine in New Zealand
Migraine disease is estimated to affect over 642,000 people in Aotearoa New Zealand
This estimate is from the Global Burden of Disease study, a huge worldwide collaborative research project that tracks the impact of hundreds of diseases and injuries in several hundred countries, including Aotearoa New Zealand.
The study measures the impact of diseases on death rates and disability, including ‘years of life lived with disability’ (YLD). Migraine is not a fatal disease but it causes significant impairment, so the YLD measure provides a way to quantify the amount and severity of this impairment.
Health and disability impact of migraine
The YLD calculates the number of years that a person lives with impaired function. It combines an estimate of how common migraine disease is in the population with the average amount of time spent with impaired function (since this varies by person) and a number called a ‘disability weight’. The disability weight is taken from large surveys where participants compare and rate the health status of individuals with differing levels of disease and disability.
In 2018, the Global Burden of Disease study found that migraine caused the second highest amount of YLD worldwide. In New Zealand, migraine ranks below low back pain and anxiety and has a similar disability impact to major depressive disorder. In 2019, the disability impact of migraine in New Zealand equated to nearly 24,000 years lived with disability. We can picture this, at the extreme, as 24,000 people living in the worst possible health state for a year. In reality, it means that there are many many thousands of people living in less than ideal health for days, weeks or months because of migraine disease.
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.
Social and economic cost of migraine
Migraine disease is most common in people of working age, and three times more common in women than men. Migraine can affect people’s ability to work, study, progress in their careers and engage in social activities and family life.
Although there have been no studies in New Zealand on the economic costs of migraine, a publication from Australia in 2018 found that the yearly cost of chronic migraine per person was AU$21,706; and AU$6,137 for episodic migraine. This included health system costs, such as paying to see health professionals and for medications, and productivity costs from the reduced ability to work and having to take time off work. If these estimates are similar for New Zealand, that would equate to around NZ$5 billion a year.
Migraine in Aotearoa New Zealand 2022 survey
In 2022, we undertook the first online survey of people with migraine in Aotearoa New Zealand. We received 579 responses. Following removal of incomplete responses and those unlikely to have migraine, we had 530 responses for analysis.
Aim of the survey
The aim of the survey was to collect data on:
Chronic migraine
Medication overuse
Types of acute and preventive medications used
Non-medication acute and preventive treatments used
Disability from migraine
Impact of migraine on work
Use of, access to and experience of health services
Experiences of stigma
What could be improved for people with migraine
