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. Around 7% of people with migraine experience the most severe and debilitating form of migraine: chronic migraine. In chronic migraine, headache occurs on 15 days or more each month. From this, we can estimate that around 45,000 people in New Zealand have chronic migraine. The remainder have episodic migraine, that occurs less than15 days per month.
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.